GSA Bulletin; January 2001; v. 113; no. 1; p. 000–000; 12 figures; 1 table.

New biostratigraphic information from the western part of theHamburg klippe, Pennsylvania, and its significance for

interpreting the depositional and tectonichistory of the klippe

G. Robert Ganis*P.O. Box 6128, Harrisburg, Pennsylvania 17112, USA

S. Henry WilliamsDepartment of Earth Sciences, Memorial University of Newfoundland, St. John’s, Newfoundland A1B 3XB, Canada

John E. RepetskiU.S. Geological Survey, 926A National Center, Reston, Virginia 20192, USA

ABSTRACT

Biostratigraphic investigation of thegraptolite and conodont faunas of the west-ern part of the Hamburg klippe of easternPennsylvania permits a revised stratigraph-ic framework and new conclusions regard-ing its likely tectonic setting. Graptolite andconodont data reveal an almost completeLower to lower Upper Ordovician zonalsection. No Cambrian strata appear to bepresent, with the possible exception of theuppermost part.

During Early to early Middle Ordoviciantime, medium- to fine-grained siliciclasticsand minor carbonate sediments were de-posited in a lower slope and rise setting.These sediments were consolidated and in-corporated as olistoliths in an olistostrome,possibly as a trench-fill complex, during theMiddle Ordovician (Darriwilian 3/4). Thisolistostrome, which contains large Lowerand lower Middle Ordovician fragmentswithin a matrix of shales, siltstones, andsandstones of Da 3/4 age, is herein namedto the Shellsville Member of the DauphinFormation. Turbidites, here assigned to theNyes Road Member of the Dauphin For-mation, were also deposited during Da 3/4time. These rocks interfinger with red bedsof the here-named Manada Hill Member ofthe Dauphin Formation. The red shales,cherts, and associated rocks of the ManadaHill Member are pelagic deposits that

*E-mail: bobganis@aol.com.

range in age from at least early Arenigthrough middle Llanvirn time. Theseallochthonous rocks were emplaced as agravity-generated klippe into the Martins-burg foreland basin during late Climaco-graptus bicornis or early Dicranograptusclingani time. These three members com-pose the Dauphin Formation (new) in thewestern part of the klippe area. Prior toemplacement of the allochthon, syntectonicflysch and scattered wildflysch of the Mar-tinsburg Formation were deposited. Somegraptolite faunas from the MartinsburgFormation, where contiguous with the klip-pe, may be slightly older than those knownfrom areas farther from the klippe. Thiscould indicate an earlier start of depositionin the Martinsburg foreland basin in ad-vance of the allochthon.

The klippe occupied a large space in theMartinsburg foreland basin and it diverteddeposition in this area until it was finallycovered by late Martinsburg age sediment.The Dauphin Formation is now structurallyinterleaved and folded with the Martins-burg Formation as a result of late Taconianand later Alleghenian tectonism.

Keywords: conodonts, graptolites, Ham-burg klippe, Martinsburg Formation,Ordovician.

INTRODUCTION

Our work describes a large number of newgraptolite and conodont localities throughout

the western end of the Hamburg klippe ter-rane. This new biostratigraphic informationwas used to delineate autochthonous from al-lochthonous rocks in the region.

Many of the graptolite and conodont zonesand successions described are new for theHamburg klippe. The allochthon in this partof the terrane is shown to be a Middle Ordo-vician olistostromal unit containing Lower Or-dovician olistoliths. Graptolite evidence con-firms that the Martinsburg foreland(Martinsburg Formation) was the host for thegravity-emplaced allochthonous componentscomposing the Hamburg klippe.

The Hamburg klippe is within the belt ofOrdovician pelitic rocks of the Great Valley(Fig. 1) of eastern Pennsylvania. The parau-tochthonous Martinsburg Formation (UpperOrdovician) is southwest and northeast of theklippe boundary. Earlier workers, includingRogers (1858), Stose and Jonas (1927), andKay (1941), recognized rocks in the area nowincluded within the klippe that were differentfrom those of the Martinsburg Formation. Inaddition, Willard (1943) reported graptolitefaunas from this area that are older than thoseof the Martinsburg Formation. Stose (1946)also reported graptolites too old for the Mar-tinsburg Formation in the same area and con-trasted the dissimilar klippe rocks, which in-cluded cherts, carbonates, volcanic rocks, andred and green shales, with those of the Mar-tinsburg. The concept of a Taconic-type klip-pe, having similarities to the classic Taconicsof New York and New England, was intro-

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Figure 1. Setting of the Hamburg klippe in eastern Pennsylvania. The figure is largely derived from a map by Faill (1997, his Fig. 10).* includes belts of Martinsburg Formation.

duced by Stose (1946). Stose’s map (Stose,1946) shows a band of the Martinsburg For-mation north of the klippe, as well as slicesof Martinsburg to the south. The Hamburgklippe is now recognized as the southernmostof the train of Taconic allochthons obductedonto the Laurentian margin (see Fig. 2) duringMiddle to Late Ordovician time.

Both the Martinsburg Formation and theHamburg klippe contain flyschoid rocks(graywacke and/or shale), which caused someworkers (e.g., Gray and Willard, 1955; Mc-Bride, 1962) to include strata within the klippein the Martinsburg Formation. Platt (in Car-swell et al., 1968) recognized the highly dis-continuous nature of the stratigraphy withinthe klippe sequence and proposed that the old-er allochthonous materials had been deliveredto and included within the Martinsburg basinvia gravity sliding. This concept differed froman entirely allochthonous klippe above theMartinsburg Formation (Stose, 1946). Thestructural and stratigraphic relationship of theolder allochthonous rocks of the Hamburg se-quence to the younger Martinsburg Formationhas been a point of debate since the klippeinterpretation was proposed. Part of the prob-lem is in determining the age of the basalMartinsburg Formation bordering the allo-

chthon. Berry (1970), Epstein and Berry(1973), Stephens et al. (1982), Parris andCruikshank (1992), and Finney et al. (1996)clarified the age of the basal Martinsburg For-mation near and adjacent to the Hamburg klip-pe. Further confusion arose from distinguish-ing tectonically induced sediments formed asa result of the allochthon transport into theMartinsburg foreland from the contents of themuch older allochthon.

On the basis of their work on the westernend of the Hamburg klippe, Root and Mac-Lachlan (1978) proposed that large discrete al-lochthons were delivered into the Martinsburgbasin by a combination of gravity sliding andthrusting. Root (1977) mapped a probablemixed terrain unit containing autochthonousMartinsburg Formation and allochthonousstrata in the U.S. Geological Survey Harris-burg West quadrangle. The Hamburg klippewas the theme of two formal field trips (Ste-phens et al., 1982; Lash et al., 1984), but bothdealt chiefly with the eastern part of the klip-pe. Lash and Drake (1984) described the east-ern part of the klippe in considerable detailand proposed a stratigraphy within the contextof an accretionary complex developed in aconvergent margin. They also proposed large

structurally distinct slices within the easternpart of the klippe.

AGE OF HAMBURG SEQUENCE:PRIOR BIOSTRATIGRAPHICEVIDENCE

The initial evidence supporting a Taconic-type klippe in eastern Pennsylvania was basedupon graptolite faunas of Early and MiddleOrdovician age found in the western part ofthe allochthon (Willard, 1943; Stose, 1946).This discovery prompted Stose (1946) to rec-ognize a distinct tectonostratigraphic divisionknown as the Hamburg klippe thrust over theyounger (Late Ordovician) Martinsburg For-mation. Willard (1943) reported graptolite fau-nas from what was thought to be the Martins-burg Formation in Dauphin County,Pennsylvania, of Normanskill (early Late Or-dovician) and Deepkill (Early Ordovician)age. Fossils from various localities reportedby Willard (1943) suggest Arenig, Llanvirn,and early Caradoc ages. Stose (1946) con-firmed and added to Willard’s Normanskilland Deepkill discoveries. Carswell et al.(1968) reported new pre-Martinsburg grapto-lites from the western part of the klippe (iden-tified by J. Riva) and a single occurrence of

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NEW BIOSTRATIGRAPHIC INFORMATION FROM THE WESTERN PART OF THE HAMBURG KLIPPE

Figure 2. Appalachian allochthonous terranes of Taconic affinity. Modified after Williams,1978 (in Bosworth, 1989).

TABLE 1. FOSSIL LOCALITY COORDINATES

Locality Locationnumber*

Latitude Longitude(�N) (�W)

G-1 40�21�03�� 76�40�54��G-2 40�21�43�� 76�40�22��G-3 40�21�40�� 76�40�19��G-4 40�21�45�� 76�40�04��G-5 40�21�52�� 76�39�53��G-6 40�22�16�� 76�39�06��G-7 south 40�22�33�� 76�39�17��G-7 north 40�22�36�� 76�39�17��G-8 (west of

studyarea)

G-9 (west ofstudyarea)

G-10 40�16�05�� 76�48�55��G-11 (east of

studyarea)

G-12 40�22�07�� 76�40�54��G-13 40�19�47�� 76�45�22��G-14 40�20�28�� 76�41�07��G-15 40�21�49�� 76�41�14��G-16 A, D, E 40�22�32�� 76�38�36��G-16 B, C 40�22�33�� 76�38�35��G-17 40�22�42�� 76�38�24��G-18 40�22�37�� 76�38�17��G-19 40�22�58�� 76�37�56��G-19 east 40�22�59�� 76�37�55��G-19 west 40�22�55�� 76�38�00��G-20 40�22�18�� 76�39�01��G-21 40�21�53�� 76�39�50��G-22 40�22�35�� 76�38�15��G-23 40�22�50�� 76�38�05��G-24 40�18�41�� 76�46�19��G-25 40�17�44�� 76�45�53��G-26 40�21�51�� 76�40�44��G-27 40�19�03�� 76�44�45��G-28 40�16�20�� 76�48�50��G-29 40�16�16�� 76�48�55��G-30 40�18�08�� 76�43�43��LP-24 (west

of studyarea)

(see Platt,1972)

*Appears without ‘‘G’’ prefix in Figure 3.

abundant Dictyonema sp. with no other forms,which led Riva (in Carswell et al., 1968) tosuggest an Early Ordovician age (Tremadoc).This ‘‘ Dictyonema’’ collection was reexam-ined and determined to be rooted dendroids ofno stratigraphic significance. Platt et al. (1972)reviewed the accumulated graptolite data fromthe Hamburg klippe and reported on severalnew collections of Middle and late Middle Or-dovician age (which are now considered LateOrdovician) from the Harrisburg area. An ac-count of graptolites from the western part ofthe Hamburg klippe was also provided byRoot and MacLachlan (1978), who reportedassemblages (identified by J. Riva) indicatingthe Nemagraptus gracilis Zone (early Cara-doc) and Didymograptus bifidus Zone (middleArenig) in 2 beds only 15 m apart at a singlelocality.

Graptolite faunas from the Hamburg klippe,summarized in Stephens et al. (1982), Lash etal. (1984), and Lash and Drake (1984), haveconsistently been referred to as indicating theNemagraptus gracilis Zone (Riva, 1972,1974) and possibly the older Hustedograptus(formerly Glyptograptus) teretiusculus Zone.In all of these summaries, literature reports ofgraptolite ages older than N. gracilis were notmentioned, except for Stephens et al. (1982),who acknowledged the report of Dictyonemasp. mentioned here.

Previous reports of conodonts from theHamburg klippe were all from localities in theeastern part of the klippe. Raring and Ganis(1973) reported several genera of Middle Or-dovician conodonts from limestones near Len-hartsville, Berks County, Pennsylvania. Thislocality was resampled in 1997; it consists of

carbonate nodules that form a discontinuousbed within a thick section of red and greenshale that also has thin volcanic ash interbeds(Ganis, 1997). The conodonts recovered are ofearly Arenig age and are of North Atlanticprovince affinity. Bergstrom et al. (1972) andEpstein et al. (1972) reported and discussedadditional conodont collections from the Len-hartsville area in strata subsequently assignedto the Windsor Township Formation by Lashand Drake (1984). They compared these fau-nas, which represent the Prioniodus elegansZone, to known coeval early Arenig faunas ofthe North American and North Atlantic faunalrealms. Combined with sedimentological andstructural evidence, they concluded that thesestrata had a southern or southeastward sourcerather than Laurentia. Repetski (1984a, 1984b)reported additional Lower Ordovician cono-donts from deeper water carbonate flysch de-posits of the Windsor Township Formation

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Figure 3. Generalized geologic map and proposed stratigraphic subdivision of the Hamburg klippe (Dauphin Formation) and associatedMartinsburg Formation in eastern Dauphin County, Pennsylvania.

and from clasts of similar lithologies incor-porated into the probable Upper OrdovicianSpitzenburg Conglomerate located �3 kmnortheast of Lenhartsville. The conodonts in-dicate the P. elegans and probably the Oepi-kodus evae Zones (early to middle Arenig).Repetski (in Lash et al., 1984; Lash andDrake, 1984) also recovered a few sparse LateCambrian and Early Ordovician conodontfaunules from the Virginville Formation �6.5km south-southwest of Lenhartsville. The sin-gle Late Cambrian collection, from the OnyxCave Member of the Virginville Formation, isthe oldest, and thus far the only unequivocalCambrian, locality dated from the Hamburgklippe. Lower Ordovician conodonts were re-covered from a limestone unit intruded by theJonestown basalts (Lofgren et al., 1999; Lash,1984; Ganis, 1997).

STRATIGRAPHIC SUMMARY

In this study the western part of the Ham-burg klippe east of Harrisburg, DauphinCounty, Pennsylvania, and just into western-most Lebanon County (see Fig. 1), wassearched for graptolites. We found 30 grap-tolite-bearing sections and spot localities (seeFig. 3); 5 of them also yielded conodonts.Fossils from these localities span the Lowerthrough lower Upper Ordovician, from theTremadoc (possibly uppermost Cambrian) tothe Caradoc (D. clingani Zone), permitting adocumentation of the stratigraphy for thewestern half of the klippe (Fig. 4). The ap-parent absence of most or all of the Cambriansection is puzzling because the depositionalhistory of Octoraro sea would seem to haveprovided for it during its Late Proterozoic

through Cambrian development (e.g., Thomas,1977; Lash et al., 1984; Lash and Drake,1984; Faill, 1997). All of the other Taconidesequences in the Appalachians, with the pos-sible exception of the Jutland and Peapackklippen in New Jersey, contain Cambrianrocks. We speculate that any missing Cambri-an rocks, assuming they ever existed, were re-moved tectonically from the rest of the se-quence, or possibly consumed duringsubduction once convergence began, duringthe Early to Middle Ordovician.

The older allochthonous sequence, compris-ing the western part of the Hamburg klippe,is herein named the Dauphin Formation, andis divided into three members. The name Dau-phin beds was used by Willard (1943) to de-scribe the Normanskill and Deepkill grapto-lite-bearing units that were to be too old for

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NEW BIOSTRATIGRAPHIC INFORMATION FROM THE WESTERN PART OF THE HAMBURG KLIPPE

Figure 4. Stratigraphy of the western part of the Hamburg klippe.

the Martinsburg Formation. The name Dau-phin beds predates all other suggested strati-graphic names for what was later to be des-ignated the Hamburg klippe. The ShellsvilleMember (herein proposed) is composed of astarved, deep-water facies suite of variegatedshales and siltstones, mudstones, thin limylayers, cherts, and pelagic red and green shalesof Da 3/4 age (D. decoratus through lowerHustedograptus teretiusculus Zones). TheShellsville Member is named for a series ofexposures along U.S. Route 22 in Dauphinand western Lebanon Counties near the townof Shellsville. A few good outcrops of thisunit display highly contorted and slumped

beds resulting from soft-sediment deforma-tion. This Middle Ordovician ShellsvilleMember is an olistostrome containing olisto-liths of Lower Ordovician strata. The olderolistoliths appear to have been emplaced inthe matrix as coherent lithified bodies. Struc-tural dislocation during the emplacement ofthe klippe and later faulting transformed theolistostrome into an olistostromal melange. Itis very difficult to estimate the true thicknessof the Shellsville Member (the outcrop widthis 1.0 km) because of its convoluted nature andthe randomly distributed olistoliths within it.

We found three Arenig age olistoliths in theShellsville Member. These olistoliths are lith-

ologically similar to the surrounding matrix.Without fossils, these rocks would be difficult,if not impossible, to differentiate. Rocks of theCounty Line olistolith (Figs. 3 and 5) containgraptolites of the lower D. bifidus Zone andthe Isograptus victoriae lunatus Zone. The ex-posure is poor and faulted and extends over afew tens of meters; it has a thickness of a fewmeters. The Hill Drive olistolith (Fig. 3) is�0.3 km long, and has an estimated thicknessof a few tens of meters. It contains graptolitesof the I. v. lunatus Zone on its eastern end andthe P. fruticosus Zone at its western end. TheRidge Top olistolith is poorly exposed in asingle outcrop at the top of a small ridge; it

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NEW BIOSTRATIGRAPHIC INFORMATION FROM THE WESTERN PART OF THE HAMBURG KLIPPE

Figure 5. Tremadoc section in the Gravel Hill Road olistolith.N

contained graptolites of the P. fruticosusZone. It is in fault contact with the older Grav-el Hill Road olistolith discussed in the follow-ing, juxtaposing Lower Ordovician rocksagainst upper Lower Ordovician rocks (Fig.5). The combined thickness of the olistolithscomposing the lower half of the Arenig Seriesis estimated as 20–50 m.

The Gravel Hill Road olistolith, comprisingpossibly all of the Tremadoc plus the lowerArenig T. approximatus Zone, is distinctivelithologically from the enclosing Llanvirn ma-trix. This olistolith consists of intervals ofblack shale and gray and/or green shale, layersof ribbon-bedded limestones, massive lime-stones, and shale with calcareous nodules(Fig. 5). The lower (Tremadoc) part of the sec-tion contains Rhabdinopora flabelliformis pa-rabola, above which are successive strata con-taining R. f. anglica and Anisograptusmatanensis, Adelograptus tenellus, and a Kia-erograptus and Clonograptus (?) fauna. TheGravel Hill Road olistolith (see Fig. 5) is �0.8km long and as wide as 0.2 km. The appar-ently complete Tremadoc section, which is be-lieved to be unaffected by folding, is �160 mthick, although faulting may distort the mea-surement. A small and isolated fragment (olis-tolith?) of black shale containing A. tenelluswas found adjacent to the main Gravel HillRoad olistolith near its eastern end (localityG-19 west; Fig. 5).

Other olistoliths probably remain to befound in this poorly exposed area. It seemslikely that some Cambrian and upper Arenig(I. v. victoriae–I. v. maximus Zones) throughlower Llanvirn (Da 1 and Da 2) olistolithswould be present in the complex, but nonehave been located.

From the time of olistostrome formationuntil emplacement of the Hamburg sequenceinto the developing Martinsburg foreland ba-sin, there is a time span of �10–12 m.y. Thiscorresponds to the time interval between theend of Da 3/4 and the beginning of the D.clingani Zone.

The Nyes Road Member is named for ex-posures along Nyes Road in Dauphin County,north of the intersection with DevonshireHeights Road. It is composed of turbidites andwell-developed Bouma cycles; thick (�1 m)graywacke sandstones represent large subma-rine canyon and fan deposits. Some exposuresof this member have interbedded red shalesbetween turbidite sequences. It has been rec-ognized west of the 5.5-km-long olistostrome

(the mapped portion of the Shellsville Mem-ber), and continues westward for at least 8 km(Fig. 3). In addition, exposures are foundalong Manada Creek south of U.S. Route 22in Dauphin County. This member is also ofDa 3/4 age, and together with the ShellsvilleMember, constitutes a belt of rock within thesame limited range of graptolite zones acrossall of Dauphin County.

In addition to the thin (�10 m) interbeds ofred shale in the Nyes Road Member, muchthicker and extensive exposures of red shaleand radiolarian chert, locally interbedded withtan, green, or purple shale, minor interbeds oflimestone or dolomite, and sparse volcanic ashlayers (discussed in Ganis, 1997), occupyprominent ridges that can be traced for manykilometers. Where such sections exceed 10 min thickness they can be mapped and are here-in assigned to the Manada Hill Member of theDauphin Formation. The Manada Hill Mem-ber is named for exposures underlying theManada Hill (spelled Manadahill on the U.S.Geological Survey topographic quadranglemap) area in eastern Dauphin County in roadcuts and shale pits. Overall, this unit compareswell with Member B, mapped in DauphinCounty by Carswell et al. (1968) as variegatedred and dark shale, mudstone, and chert. Col-lectively, this lithofacies constitutes a largetemporal range of distal, deep-water depositsthat was broken and interleaved into otherlower slope components during the initial pro-grading sedimentation and during transport ofthe klippe and subsequent structural defor-mation. Exposures of this lithofacies in a shalepit at Lenhartsville, Pennsylvania (east of thestudy area), contain ash beds and associatedlayers of carbonate nodules that were dated asEarly Ordovician (early Arenig) by conodonts(Repetski, in Ganis, 1997). Stephens et al.(1982) reported N. gracilis Zone (Riva, 1972,1974) graptolites from red shale in the easternpart of the klippe.

There is no evidence that rocks were de-posited between late Da 4 through late N.gracilis to early C. bicornis Zone time, i.e.,the interval between deposition of the Dau-phin Formation (the allochthon) and that ofthe earliest Martinsburg foreland deposits de-scribed below. We suggest that deposition wasinterrupted during the obduction of the Ham-burg sequence on the Laurentian margin dur-ing that time.

Within the mapped limits of the Hamburgklippe are belts of turbiditic flysch and wild-

flysch deposits that have yielded graptolites ofthe upper C. bicornis Zone (D. multidensZone of Riva, 1969, 1974) through the youn-ger D. clingani Zone (C. americanus Zone ofRiva, 1969, 1974; Berry, 1960, 1970, 1971)that should be retained within the MartinsburgFormation. A C. bicornis Zone age (sensuBerry, 1960; Williams, 1995) was recorded byWright et al. (1979; ascribed to the D. multi-dens Zone therein) and Finney et al. (1996)for the oldest Martinsburg bordering the Ham-burg klippe to the southwest. Epstein and Ber-ry (1973) and Parris and Cruickshank (1992)estimated the basal Martinsburg Formation ineastern Pennsylvania to be of similar age. Fig-ure 3 shows the belts of the Martinsburg For-mation as they relate to the members of theallochthonous Dauphin Formation within thestudy area. The presence of Pseudoclimaco-graptus stenostoma and P. scharenbergi insome of the Martinsburg localities contiguouswith the allochthonous klippe strata may in-dicate that syntectonic Martinsburg flysch de-position began earlier, in advance of the allo-chthon, because these taxa are not presentelsewhere in the Martinsburg Formation out-side the klippe boundary.

Stose (1946) showed a thin band of Mar-tinsburg Formation extending across thenorthern part of the klippe on its western part.This map pattern was retained by some laterworkers (e.g., Platt et al., 1972; Root andMacLachlan, 1978; Faill, 1997), but not byothers (e.g., Stephens et al., 1982; Lash et al.,1984; Lash and Drake, 1984). Stose (1946)also indicated small slivers of Martinsburgsouth of the klippe. Our study shows thatmuch more of the area traditionally mappedas the Hamburg klippe should be retainedwithin the Martinsburg Formation, not just asfringe areas to the north and south, but as in-terleaved belts with the older allochthonouscomponents. The structural relationship ofthese belts has not been determined. The al-ternating belts of the Martinsburg and Dau-phin Formations may connect as folds or re-peat from faulting. Alternately, the allochthonmay have slid into the Martinsburg forelandin pieces, as suggested by Carswell et al.(1968), rather than as one mass, as suggestedby Wright and Stephens (1978) and Wright etal. (1979).

Another characteristic of the MartinsburgFormation, where it is contiguous with the al-lochthonous components, is the presence ofscattered boulder conglomerates (wildflysch).

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Figure 6. Tremadoc graptolites from the Hamburg klippe. All figured specimens are reposited in type collections of the Department ofPaleobiology, U.S. National Museum of Natural History (USNM), Washington, D.C. Locality is indicated by brackets. (A–D) Rhabdi-nopora flabelliformis parabola (Bulman), 44 m level, Gravel Hill Road (north) [G-7]. A, B, �10; C, D, �5; USNM 509823–826, respec-tively. (E, F, J, K–M) Rhabdinopora flabelliformis subsp. cf. R. f. anglica (Bulman), [G-19]. L, �2.5, M, �10, others, �5 (L is also inFig. 11D); USNM 509827–832, respectively. (G–I) Anisograptus matanensis Ruedemann, [G-19], �5; USNM 509833–835, respectively.(N–R) Adelograptus tenellus (Linnarsson), 135–145 m level, Gravel Hill Road [G-7], �10; USNM 509836–840, respectively. (S, T) Kia-erograptus bulmani (Thomas), 157 and 161 m levels, Gravel Hill Road [G-7], �10; USNM 509841 and 509842, respectively.

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Figure 7. Arenig graptolites from the Hamburg klippe. All figured specimens are reposited in type collections of the Department ofPaleobiology, U.S. National Museum of Natural History (USNM), Washington, D.C. Locality is indicated by brackets. (A, B) Pendeo-graptus sp. cf. P. pendens (Elles), 164.3 m level, Gravel Hill Road [G-7], �5; USNM 509843 and 509844. (C, D) Tetragraptus approximatusapproximatus (Nicholson), 164.3 m level, Gravel Hill Road [G-7], �5; USNM 509845 and 509846, respectively. (E–G) Pendeograptusfruticosus (J. Hall), �5. E, [G-5 west], F, G, [G-16A]; USNM 509847–849 respectively. (H) Pseudotrigonograptus ensiformis (J. Hall),[G-16D], �5; USNM 509850. (I–L) Didymograptus (Didymograptellus) bifidus (J. Hall), [G-16A], �5; USNM 509851, respectively. (M,N) Keblograptus bidens (Keble), [G-16D], �5; USNM 509855 and 509856, respectively. (O–R) Didymograptus (Expansograptus) constrictus(J. Hall), [G-5 west], �5; USNM 509857–860, respectively. (S, T) Didymograptus (Expansograptus) similis (J. Hall), [G-5 west], �5;USNM 509861 and 509862, respectively. (U–X) Didymograptus (Expansograptus) abditus Williams and Stevens, [G-5 east], �5; USNM509863–866, respectively. (Y–B�) Xiphograptus svalbardensis (Archer and Fortey), [G-5 east], �5; USNM 509867–870, respectively. (C�)Acrograptus sp. cf. A. gracilis (Tornquist), [G-18], �5; USNM 509871. (D�, ��) Goniograptus thureaui (M’Coy), [G-5 east], �5; USNM509872 and 509873, respectively. (F�–��) Isograptus victoriae victoriae Harris, [G-5 east], �5; USNM 509874–879, respectively.

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Figure 8. Darriwilian (middle Llanvirn) graptolites from the Hamburg klippe. All figured specimens are reposited in type collections ofthe Department of Paleobiology, U.S. National Museum of Natural History (USNM), Washington, D.C. Locality is indicated by brackets.(A–C) Pterograptus elegans Holm, �5. A, [G-16c], B, [G-2], C, [G-21]; USNM 509880–882, respectively. (D) Pseudophyllograptus sp., [G-3], �2.5; USNM 509833. (E–I) Archiclimacograptus riddellensis (Harris), [G-3]. D–F, �10, G–I, �5; USNM 509884–888, respectively.

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(J–L) Archiclimacograptus sp., [G-3]. J, �10, K, L, �5; USNM 509899–891. (M–P) Hustedograptus sp. cf. H. teretiusculus (Hisinger)(sensu Maletz, 1997). M, N, P, [G-3], O, [G-1], �5; USNM 509892–895, respectively. (Q–T) Haddingograptus oliveri (Boucek), [G-3]. Q,�10, R–T, �5; USNM 509896–899, respectively. (U) Diplograptid sp. indet., [G-4], �2.5; USNM 509900. (V�A�) Cryptograptus schaferi(Lapworth). V, Y, [G-16D], W, [G-16D], X, Z, [G-3], A�, [G-6], V, W, �10, X–A� �5; USNM 509901–906, respectively. (B�, D�) Par-aglossograptus tentaculatus (J. Hall). B�, [G-17], D�, [G-3], �5; USNM 509907 and 509908, respectively. (C�, E�) Glossograptus holmiBulman, [G-3] �5; USNM 509909 and 509910, respectively. (F�, G�) Kalpinograptus sp., [G-20], �10; USNM 509911 and 509912.N

The matrix shale at one of these exposures (G-30; Table 1) has early Caradoc graptolites.This matrix encloses both angular graywackeblocks and soft-sediment deformed irregularmasses. Root and MacLachlan (1978) mappedthe ‘‘ Conodoguinnet wildflysch’’ near thenorthwestern edge of the allochthon, whichthey described as allochthonous graywacke inautochthonous shale. Stephens et al. (1982) re-ported graptolites from that sequence as be-longing to the D. multidens or C. americanusZone (C. bicornis to D. clingani Zones of Wil-liams, 1995). Lash and Drake (1984) de-scribed similar but undated deposits in theeastern part of the Hamburg klippe. Theseboulder conglomerates of the MartinsburgFormation may be analogous to the blocks-in-shale of the Snake Hill Formation (Norman-skill of some authors) of the classic Taconicregion of New York (Landing, 1986; Berry,1962) and are about the same age. This sce-nario also appears comparable to the Pawletto Austin Glen Formation transition describedby Zen (1968) in the New York TaconicMountains. The transition from syntectonic(and possibly allochthonous) flysch to autoch-thonous Martinsburg is gradational and ap-pears to have occurred within the upper C.bicornis to lower D. clingani Zones.

BIOSTRATIGRAPHY

Graptolite faunas (Figs. 6–11) ranging inage from early Tremadoc to Caradoc from anumber of graptolitic intervals have been rec-ognized. They can be matched closely withsequences elsewhere in the Appalachians, par-ticularly western Newfoundland (Cooper etal., 1998; Williams and Stevens, 1988, 1991),Quebec (Maletz, 1997a), and the southeasternUnited States (e.g., Finney, in Ross et al.,1982). A relatively complete succession ispresent from the early Tremadoc (Rhabdino-pora flabelliformis parabola Zone) through tothe middle Arenig (Isograptus victoriae Zone)in olistoliths contained within the ShellsvilleMember of the Dauphin Formation. The nextbiostratigraphic level identified, which consti-tutes the Shellsville Member matrix, is theequivalent of the ‘‘Diplograptus’’ decoratusZone of Australia (Da 3; Vandenberg and

Cooper, 1992) or the Pterograptus elegansZone of Scandinavia (sensu Maletz, 1997b)and eastern Canada (Mitchell and Maletz,1994); the late Arenig and earliest Llanvirn(Darriwilian) has thus not been recognized.Following this, the youngest interval recog-nized, which is within the Martinsburg For-mation, includes the Late Ordovician C. bi-cornis Zone (lower Diplograptus multidensZone of some authors) and D. clingani Zone.Although assemblages indicative of the pre-ceding Nemagraptus gracilis Zone (as definedby Riva, 1972, 1974) have been recoveredelsewhere to the east in the Hamburg klippe,only taxa indicative of the equivalent upperpart of that zone, representing the C. bicornisZone as defined by Williams (1995), havebeen recognized in our area.

The lowest biostratigraphic level within theGravel Hill Road olistolith taxa at locality G-23 (Figs. 3 and 5) yielded conodonts (Fig. 12)from nodular limestones and dark gray, cal-careous shale that demonstrates an earliest Or-dovician (very early Ibexian) age. The pres-ence of Iapetognathus spakersi Landing,Cordylodus lindstromi Druce and Jones, andRossodus tenuis (Miller) indicates assignmentto the Cordylodus angulatus Zone of NorthAmerican usage (Ross et al., 1997). This in-terval correlates with part of the broader Cor-dylodus angulatus Zone of the North Atlanticconodont realm (Lofgren, 1997). Overlyingthese carbonates, a calcarenite sequence hasyielded a few unidentifiable graptolite frag-ments, possibly belonging to benthic den-droids. This interval is analogous to that foundin the earliest Ordovician at the proposedCambrian-Ordovician boundary stratotype atGreen Point, western Newfoundland. There,calcarenites of Bed 24 that are immediatelyabove the defined systemic boundary in themiddle of Bed 23 (based on conodonts) con-tain fragments of benthic dendroids that mayhave been transported from a shelf environ-ment. The earliest planktic graptolites (Rhab-dinopora praeparabola (Bruton, Erdtmann,and Koch) and Staurograptus dichotomus(Emmons) first occur at Green Point severalmeters higher in an alternating limestone andshale sequence assigned to Bed 25 (Cooper etal., 1998).

The earliest identifiable graptolites in thearea come from dark gray shales in a smallroadside outcrop at G-7 (north) along GravelHill Road immediately north of Route 22 (Fig.5). Here, a number of small specimens havebeen recovered at the 44 m level; they closelymatch Cooper et al.‘s (1998) redescription ofRhabdinopora flabelliformis parabola (Bul-man) (Fig. 6). No graptolites have been foundthat indicate the underlying R. praeparabolaZone of Cooper et al. (1998). The dark grayshales of the R. f. parabola Zone are followedby a moderately thick sequence (�80 m) ofunfossiliferous pale buff to gray-green shalethat is traceable along strike to locality G-19(Fig. 5). One level at this locality (G-19),however, has yielded both graptolites and co-nodonts from an interval of alternating darkgray siltstone and calcareous nodules. Thegraptolites include Rhabdinopora, which,based on Cooper et al. (1998), appear to bemorphologically midway between R. flabelli-formis flabelliformis (Eichwald) and R. flabel-liformis anglica (Bulman) (see Figs. 6, 10,and 11), and Anisograptus matanensis Rue-demann (Fig. 6). This suggests a correlationwith either the Anisograptus matanensis or R.f. anglica Zone of the later early Tremadoc ofCooper et al. (1998). The sparse collection ofconodonts (Fig. 12), including Rossodus ten-uis (Miller) and Drepanoistodus pervetusNowlan?, suggests the Cordylodus angulatusZone interval; this is consistent with the lateearly Tremadoc age.

The remainder of the Tremadoc and earliestArenig sequence has been seen within theGravel Hill Road olistolith to the south ofRoute 22 at locality G-7 (south) (Fig. 5),where the lowest exposures apparently belongto the largely unfossiliferous pale shale dis-cussed here. These are followed by 24 m ofblack shale that yield an abundant monospe-cific fauna of beautifully preserved Adelo-graptus tenellus (Linnarsson) (Figs. 6 and 11).Although this species appears to rangethroughout much of the late Tremadoc (Coo-per, 1999), the lack of any later forms heresuggests to us the presence of the earliest lateTremadoc A. tenellus Zone. This level is fol-lowed by mostly unfossiliferous pale siltstoneand sandstone. A poorly preserved but diverse

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Figure 9. Caradoc graptolites from the Hamburg klippe. All figured specimens are reposited in type collections of the Department ofPaleobiology, U.S. National Museum of Natural History (USNM), Washington, D.C. Locality is indicated by brackets. (A–C) Dicello-graptus intortus Lapworth, [G-12], �5; USNM 509913–915, respectively. (D, E) Dicellograptus salopiensis Elles and Wood, [G-12], �5;USNM 509916 and 509917, respectively. (F) Dicranograptus sp. cf. D. ramosus spinifer Elles and Wood, [G-30], �5; USNM 509918. (G)Pseudoclimacograptus scharenbergi (Lapworth), [LP-24], �5; USNM 509919. (H) Pseudoclimacograptus stenostoma (Bulman), [LP-24],�5; USNM 509920. (I) Diplograptus? sp. cf. D. foliaceus (Murchison), [G-10], �5; USNM 509921. (J, K) Orthograptus ex gr. calcaratus(Lapworth), [G-28], �5; USNM 509922 and 509923 respectively. (L) Climacograptus bicornis (J. Hall), [G-10], �5; USNM 509924. (M,N) Corynoides calicularis Nicholson, [G-28], �5; USNM 509925 and 509926 respectively. (O, P) Orthograptus quadrimucronatus (J. Hall),[G-28], �5; USNM 509927 and 509928, respectively. (Q, R) Climacograptus antiquus Lapworth, [G-12], �5; USNM 509929 and 509930,respectively. (S) Reteograptus geinitzianus J. Hall, [G-12], �5; USNM 509931.

late Tremadoc graptolite assemblage was re-covered at the 157 m level; the assemblageappears to include at least two Kiaerograptusspecies, including K. bulmani (Thomas) (Fig.6), together with Clonograptus? sp. and pos-sibly Aorograptus victoriae (T.S. Hall). These

specimens, although fragmentary, are identicalin terms of proximal development to those de-scribed by Williams and Stevens (1991) fromthe late Tremadoc interval of the Cow HeadGroup of western Newfoundland; they indi-cate the presence of the Aorograptus victoriae

Zone. Within the lower meter of the succeed-ing ribbon limestones (at 161.5 m), a sparsebut similar assemblage was recovered.

From this level and within the succeedingmeter of the limestone, conodonts recovered(Fig. 12) include Prioniodus oepiki (Mc-

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Tavish), Prioniodus? n. sp., Paltodus subae-qualis Pander, Paroistodus proteus (Lind-strom), Oelandodus aff. O. elongatus(Lindstrom), Drepanodus arcuatus Pander,Paracordylodus gracilis Lindstrom, Tripodusalbanii Stouge and Bagnoli, Periodon primusStouge and Bagnoli?, and Oneotodus costatusEthington and Brand. Stouge and Bagnoli(1988) recorded this association from the low-er half of Bed 9 at the Ledge�Point of Headsection in the Cow Head Group on the CowHead Peninsula, western Newfoundland. Theyassigned this interval to their Prioniodus oep-iki and P. adami Zones. This interval of theCow Head Group is within the lower three-quarters of the Tetragraptus approximatusZone (Williams and Stevens, 1988) or thelowermost Arenig. In the uppermost part ofthe section exposed at locality G-7, one hori-zon at 164.3 m yielded Tetragraptus approx-imatus approximatus (Nicholson) (Fig. 7) inassociation with ’’ Pendeograptus sp. cf. P.pendens’’ (Elles) (Fig. 7) and Clonograptusflexilis (J. Hall)?, indicating the earliest Ar-enig. Thus, in one section, an �165 m se-quence spanning the early Tremadoc throughearliest Arenig appears to occur in biostrati-graphic order. High-angle faults have, how-ever, been recognized locally and we believethat the section is unlikely to be continuous orstratigraphically complete.

Later early and early middle Arenig grap-tolites (Fig. 7) have been recovered from threeolistoliths within the Shellsville Member, atlocalities G-5, G-16, and G-18 (Figs. 3 and 5).At G5, a thin sequence of siltstones and sand-stones has yielded two zonally diagnostic as-semblages. At the west end of the exposure,the graptolites include Pendeograptus fruti-cosus (J. Hall), Phyllograptus? sp., Didymo-graptus (Expansograptus) constrictus (J.Hall), D. (E.) nitidus (J. Hall)?, D. (E.) similis(J. Hall), and Xiphograptus svalbardensis (Ar-cher and Fortey). In the Cow Head Groupthese graptolites all occur in the P. fruticosusZone, with the exception of D. (E.) constric-tus, which is restricted to the underlying T.akzharensis Zone. Williams (1992), however,reported D. (E.) constrictus from rocks be-longing to the P. fruticosus Zone in west-cen-tral Newfoundland, and it may thus be con-cluded that this is the level represented at G-5(west). At the east end of the exposure, taxainclude Didymograptus (Expansograptus) ab-ditus Williams and Stevens, Keblograptus bi-dens (Keble), X. svalbardensis, Acrograptussp. cf. A. gracilis (Tornquist), and Goniograp-tus thureaui (M’Coy), in association with acommon Isograptus which seem to mostclosely match Isograptus victoriae victoriae

Harris (although some specimens are moresimilar in form to I. v. lunatus Harris; see Wil-liams and Stevens, 1988). Similar assemblag-es are found in both the earliest Middle Or-dovician I. v. lunatus Zone and the followingI. v. victoriae Zone, but the large size of theIsograptus specimens suggests a correlationwith the I. v. victoriae Zone. In the Cow HeadGroup, the P. fruticosus and I. v. victoriaeZones are separated by the D. bifidus and I. v.lunatus Zones; however no specimens of D.(D.) bifidus (J. Hall) or of typical I. v. lunatuswere recovered from this section. This maysuggest the presence of significant but indis-tinguishable bedding-parallel faulting, or agap in deposition.

The D. bifidus Zone and possibly the I. v.lunatus Zone (or alternatively the I. v. victo-riae Zone) are, however, represented at thewestern end of G-16 (G-16a) (Fig. 5), whereD. (D.) bifidus (J. Hall) occurs in associationwith P. fruticosus (J. Hall), D. (E.) similis (J.Hall), X. svalbardensis (Archer and Fortey),and G. thureaui (M’Coy) with abundant co-nodonts in a fine-grained sandstone. The co-nodonts, including Oepikodus evae (Lind-strom), are indicative of the Oepikodus evaeZone. In the Cow Head Group, D. (D.) bifidusand P. fruticosus overlap only in the lowerhalf of the D. bifidus Zone (Williams and Ste-vens, 1988). Several meters to the east, G-16dand G-16e yield a diverse I. v. lunatus or I. v.victoriae Zone assemblage, including Isograp-tus dilemma Williams and Stevens?, Tetra-graptus reclinatus reclinatus Elles and Wood,K. bidens (Keble), X. svalbardensis (Archerand Fortey), Phyllograptus typus (J. Hall),Pseudotrigonograptus ensiformis (J. Hall),and G. thureaui (M’Coy), together with a fewpoor Isograptus specimens which appear tomost closely match I. v. lunatus Harris. At G-18 in the Ridge Top olistolith, a poorly pre-served fauna was recovered that includes asingle specimen of D. (E.) constrictus (J.Hall), X. svalbardensis (Archer and Fortey),and a probable specimen of Acrograptus sp.cf. A. gracilis (Tornquist). This assemblage isconsistent with an early to middle Arenig age(probably P. fruticosus Zone). Although A.gracilis was not collected below the I. v. lun-atus Zone in Newfoundland by Williams andStevens (1988), these authors mentioned thatthe species had been recorded from lower in-tervals elsewhere.

No later Arenig or early Llanvirn (Darri-wilian 1 and 2) assemblages have yet beenrecovered from the study area. Middle Llan-virn (Da 3 or Da 4) graptolite localities (G-1,G-2, G-3, G-4, G-6, G-13, G-14, G-15, G-16b,G-16c, G-17, G-19 east, G-20, G-21, G-24,

and G-27) in strata that constitute the matrixof the Shellsville Formation (Fig. 3) are, how-ever, numerous and their faunas (Figs. 8 and10) may be compared taxonomically withmany of the taxa redescribed recently from theOslo region by Maletz (1997b) and westernNewfoundland by Taylor (1997). Diverse as-semblages include Pterograptus elegansHolm, Archiclimacograptus riddellensis (Har-ris), Archiclimacograptus sp., Hustedograptussp. cf. H. teretiusculus (Hisinger) (sensu Mal-etz, 1997b), Haddingograptus oliveri (Bou-cek), Cryptograptus schaeferi (Lapworth),Paraglossograptus tentaculatus (J. Hall),Glossograptus holmi Bulman, Kalpinograptussp., Pseudophyllograptus sp., Bergstroemo-graptus crawfordi (Harris)?, and Reteograp-tus? sp., together with a number of benthicdendroids including Dendrograptus. Suchtaxa are identical to those described from theTable Cove and Black Cove Formations ofwestern Newfoundland (Finney and Skeving-ton, 1979; Mitchell and Maletz, 1994; Taylor,1997) and also bear considerable similarity toassemblages of similar Da 3/4 age elsewherein the world (see Maletz, 1997b). Mitchell andMaletz (1994) and Maletz (1997b) consideredthe presence of P. elegans to indicate the P.elegans Zone of earliest Da 4 age, as opposedto the earlier Nicholsonograptus fasciculatusZone (latest Da 3). Taylor (1997) recorded N.fasciculatus (Nicholson) from both the TableCove and Black Cove Formations, P. elegansbeing restricted to the laterally equivalent (?)Cape Cormorant Formation. In our opinion,the ranges of these taxa are insufficientlyknown to justify definite biostratigraphic sub-division and we therefore refer this assem-blage to Da 3/4. Conodonts from locality G-4(Fig. 3) are poorly preserved, but among thefragments are some with morphologies con-sistent with Middle Ordovician taxa.

The youngest strata in the area belong tothe Martinsburg Formation of early Caradocage (Climacograptus bicornis through Di-cranograptus clingani [?Corynoides ameri-canus] Zones). The richest graptolite assem-blages for the earliest part of the sequence arepresent at G-10, G-12, and LP-24 (Fig. 9),where, on the basis of taxonomic comparisonwith descriptions by Finney (1980), Hughes(1989), and Williams (1995), the fauna in-cludes Dicellograptus intortus Lapworth, D.salopiensis Elles and Wood, Climacograptusbicornis (J. Hall), Climacograptus antiquusLapworth, Diplograptus sp. cf. D. foliaceous(i.e., cf. D. multidens; see Hughes, 1989), Or-thograptus calcaratus subsp., O. amplexicau-lis subsp., Pseudoclimacograptus scharenber-gi (Lapworth), P. stenostoma (Bulman), and

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Figure 11. Photoplate of selective graptolite taxa, Hamburg klippe. All figured specimens are reposited in type collections of the De-partment of Paleobiology, U.S. National Museum of Natural History (USNM), Washington, D.C. Locality is indicated by brackets. (A,B) Adelograptus tenellus (Linnarsson), 135–140 m level, Gravel Hill Road [G-7], �10; USNM 509836 and 509946. (C) Glossograptus sp.,[G-26], �20; USNM 509947. (D) Rhabdinopora flabelliformis subsp. cf. R. f. anglica (Bulman), [G-19], �5 (also in Fig. 6L); USNM509831. (E, F) Reteograptus geinitzianus J. Hall, [G-26]. E, �20, F, �10; USNM 509949 and 509950, respectively.

Figure 10. Photoplate of selective graptolite taxa, Hamburg klippe. All figured specimens are reposited in type collections of the De-partment of Paleobiology, U.S. National Museum of Natural History (USNM), Washington, D.C. Locality is indicated by brackets. (A,B) Archiclimacograptus riddellensis (Harris), [G-3], A, �10, B, �20; USNM 509932 and 509933, respectively. (C, D) Haddingograptusoliveri (Boucek), [G-3], C, �10, D, �20; USNM 509897 and 509898, respectively. (E, F) Hustedograptus sp. cf. H. teretiusculus (Hisinger)(sensu Maletz, 1997b), [G-3], E, �10, F, �20; USNM 509936 and 509937, respectively. (G) Glossograptus holmi Bulman, [G-3], �5;USNM 509938. (H) Pseudophyllograptus sp., [G-17], �20; USNM 509939. (I, J) Cryptograptus schaferi (Lapworth). I, [G-3], �20, J, [G-20], �10; USNM 509940 and 509941, respectively. (K) Archiretiolitid sp. nov.?, [G-20], �20; USNM 509942. (L) Anisograptus matanensisRuedemann, [G-19], �10; USNM 509943. (M) Rhabdinopora flabelliformis subsp. cf. R. f. anglica (Bulman), [G-19], �1.5; USNM 509944.N

Reteograptus geinitzianus J. Hall (Figs. 9 and11) in association with benthic dendroids. J.Riva (written communs. to T.O. Wright, 1976;R.D.K. Thomas, 1980; and R. Ganis, 1997)referred such assemblages present in this partof the sequence to the Nemagraptus gracilisZone. Williams (1995), however, restricted theunderstanding of the N. gracilis Zone in New-foundland, considering it to be characterizedby the occurrence of N. gracilis (J. Hall) and/or Acrograptus superstes (Lapworth) andlacking C. bicornis. He considered the follow-ing Climacograptus bicornis Zone (lower D.multidens Zone of many authors) to be dom-inated by more diverse diplograptid assem-blages, together with species of Corynoides;

both N. gracilis and A. superstes also occur inthe earliest part of the C. bicornis Zone. Webelieve that the assemblages examined in thisstudy indicate this higher level for the earliestpart of the sequence rather than the earliestCaradoc N. gracilis Zone; this is apparentlyconfirmed in G-26 (Fig. 3), where Corynoidessp. cf. C. calicularis Nicholson occurs in apoorly preserved assemblage together withCryptograptus tricornis (Carruthers)?, Glos-sograptus sp., and Reteograptus geinitzianusJ. Hall. However, J. Riva (1997, written com-mun. to Ganis) considered this level to belongto the N. gracilis Zone. The Martinsburg For-mation in this study area in the previouslymapped Hamburg klippe (sensu Stose, 1946)

continues into the D. clingani Zone, demon-strated by assemblages from locality G-28(Fig. 9) that include Orthograptus quadrimu-cronatus (J. Hall), O. ex. gr. Calcaratus (Lap-worth), and Corynoides calicularis Nicholson,and from G-30, where Dicranograptus ramo-sus cf. D. spinifer was recovered. This levelcorrelates with the Bushkill and/or Ramsey-burg Members of the Martinsburg Formationin eastern Pennsylvania (Parris and Cruik-shank, 1992).

COMPARISON TO THE EASTERNEND OF THE KLIPPE

Lash and Drake (1984) and Lash et al.(1984) studied the eastern half of the Ham-

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Figure 12. Lower Ordovician conodonts from the Hamburg klippe. All views lateral except as noted. All figured specimens are repositedin type collections of the Department of Paleobiology, U.S. National Museum of Natural History (USNM), Washington, D.C. Locality isindicated by brackets. (A, B, F, Q, R) Rossodus tenuis (Miller), A, �150 and F, �125, posterolateral views; R, �150, posterior view ofconiform elements, B, �200, Q, �125, oistodontiform elements; A, B, F, [G-23] (U.S. Geological Survey [USGS] locality 11559-CO); Q,R, [G-19] (USGS locality 11560-CO); USNM 509951–955, respectively. (C, D) Iapetognathus sprakersi Landing, Westrop, and Knox,upper and lateral views of two specimens, [G-23] (USGS loc. No. 11559-CO0, �350 and �150, respectively; USNM 509956 and 509957.(E) Cordylodus lindstromi Druce and Jones, �150, [G-23] (USGS loc. No. 11559-CO; USNM 509958. (G) Periodon primus Stouge andBagnoli?, P(?) element �100, locality 2 of Ganis (1997) (USGS loc. No. 11561-CO) (carbonate nodules from Lenhartsville); USNM509959. (H, I) cf. Acodus deltatus deltatus Lindstrom. H, M element �125, and I, P element �150, locality 2 of Ganis (1997) (USGS loc.No 11561-CO) (carbonate nodules from Lenhartsville); USNM 509960 and 509961 respectively. (J–N, P, A�, ��) Prioniodus oepiki(McTavish). J, Pa element �100; K, B�, Sd element �125; L, posterolateral view of Sa element �100; M, Pb element �100; N, A�, Melements �75 and �100; P, Sb element, �75; J–N, P are from locality 2 of Ganis (1997) (USGS 11561-CO) (carbonate nodules fromLenhartsville); A�, [G-7 south] (USGS loc. 11562-CO); USNM 509962–969, respectively. (O) Tropodus comptus (Branson and Mehl),outer lateral view, �75, locality 2 of Ganis (1997) (USGS 11561-CO; USNM 509970) (carbonate nodules from Lenhartsville). (S) Par-acordylodus gracilis Lindstrom, S element, �100, locality 2 of Ganis (1997) (USGS 11561-CO) (carbonate nodules from Lenhartsville);USNM 509971. (T) Tripodus albanii Stouge and Bagnoli, anterolateral view of S element, �125, locality 2 of Ganis (1997) (USGS 11561-CO) (carbonate nodules from Lenhartsville); USNM 509972. (U) Drepanoistodus pervetus Nowlan? �150, [G-19] (USGS loc. 11560-CO);USNM 509973. (V) Drepanodus arcuatus Pander, �75, [G-7 South] (USGS loc. 11562-CO); USNM 509975. (W) Prioniodus? n. sp. Pelement, �75, [G-7 south] (USGS loc. 11562-CO); USNM 509975. (X, Z, C�, D�) Paltodus subaequalis Pander, S elements, X, D�, �75and �75, respectively; Z, Sa(?) element �75; C�, M element �75, [G-7 south] (USGS loc. 11562-CO); USNM 509976–979, respectively.(Y, E�, ��) Paroistodus proteus (Lindstrom). Fused pair (Y) �100, M element (E�) �75, and S element (H�) �75, [G-7 south] (USGSloc. 11562-CO); USNM 509980–982, respectively. (F�) Oelandodus elongatus (Lindstrom). �75, [G-7 south] (USGS loc. 11562-CO); USNM509983. (G�) Oneotodus costatus Ethington and Brand, �100, [G-7 south] (USGS loc. 11562-CO); USNM 509984N

burg klippe in considerable detail and devel-oped a structural and stratigraphic frameworkfor that area. The sedimentology suggested tothem that the Hamburg klippe originated as anaccretionary complex at a convergent margin(Lash et al., 1984). The biostratigraphic con-trol available to them in their work was builtlargely upon earlier graptolite reports sum-marized in Stephens et al. (1982) and new co-nodont discoveries from the carbonate facies.The graptolites reported by Stephens et al.(1982) were almost entirely considered to in-dicate the N. gracilis Zone (sensu Riva, 1972,1974), apart from one locality of possible H.teretiusculus Zone, and one locality contain-ing ‘‘ Dictyonema’’ provisionally given an Ear-ly Ordovician age (see Carswell et al., 1968;Platt et al., 1972).

In contrast, in our area, we found a broadsweep of graptolites in clastic rocks havingages spanning almost the entire Early, Middle,and early Late Ordovician. Their ages are sup-ported by occasional conodont control chieflyfrom carbonate interbeds. Comparing our areawith detailed biostratigraphic control with an-other area having little biostratigraphic controlis challenging. Lash and Drake (1984) for-mally proposed the Virginville Formation toinclude units of Late Cambrian and Early Or-dovician age. Most of the rocks that they de-scribed, namely olive-green siltstone, calcar-enite, and ribbon limestone and black shale,fit the rocks occurring in the section of Tre-madoc age described herein. Near Shoemak-

ersville, Berks County, Pennsylvania (east ofour study area), Late Ordovician (Caradoc)graptolites were recovered from the Glen-Gery Corporation brick-shale pit within theMoselem Member mapped by Lash et al.(1984), which is part of their Virginville For-mation. In contrast, we would retain this unitin the Martinsburg Formation. Our Lower Or-dovician section is represented only by olis-toliths. Lash and Drake (1984) described po-lymict carbonate-clast conglomerate withintheir Moselem Member, dated as Early Or-dovician by conodonts, that does not occur inthe Lower Ordovician section of our studyarea. This same lithology, also dated as EarlyOrdovician by conodonts (Repetski, in Ganis,1997), was found to the east of our study areaas a boulder conglomerate within a matrix ofgraywacke flysch. The Windsor TownshipFormation of Lash and Drake (1984) is mostlya turbiditic flysch sequence belonging to theN. gracilis Zone (Riva, 1972, 1974) that con-tains older olistoliths of chert, limestone, var-iegated shale, and mudstone. In our study areawe found abundant turbiditic flysch both inthe Nyes Road Member of the Dauphin For-mation, of Da 3/4 (Llanvirn) age, and in theLate Ordovician Martinsburg Formation. OurShellsville Member olistostrome has no ap-parent comparative unit to those described byLash et al. (1984) or Lash and Drake (1984).

Given the potential for lateral facies varia-tion within any time interval among the dif-ferent parts of the klippe, specific lithologic

correlation between units in our mapped areaand those of another areas would be tenuous.For this reason, we have erected new strati-graphic units with the provision that reconcil-iation with previously named units outside ourstudy area may be possible with additionalstudy. Lash and Drake (1984) also describedthe Richmond and Greenwich structural slices,partly by structural styles. We made no at-tempt to extend these structurally defined unitsinto our area.

HISTORICAL DEVELOPMENT

Using the stratigraphic sequence found inour study area, the Hamburg klippe appears tohave been formed during three broad geologicevents. First, during a period of �25 m.y.,from the earliest Ordovician (possibly latestCambrian) through the Early Ordovician.(Tremadoc to medial Arenig), a sediment-starved lower slope and rise sequence wasdeposited.

Second, this sequence was consolidated,fragmented, and emplaced, probably by grav-ity slides, as olistoliths into a matrix of youn-ger lower slope and rise sediments that un-derwent extensive soft-sediment deformation.This olistostrome is our Shellsville Member.These data suggest deformation during trenchfilling in a subduction complex. On the basisof their work in the eastern part of the Ham-burg klippe, Lash et al. (1984) and Lash andDrake (1984) also suggested that much of the

Geological Society of America Bulletin, January 2001

GANIS et al.

Hamburg sequence underwent these events.Probably at this time the subducting slabflexed, allowing localized outpouring of ba-saltic magma (the Jonestown Volcanics), asproposed by Lash 1984 in an olistostrome (?)containing Arenig-age limestone olistoliths.What is surprising is the relatively short timeinterval during which this olistostromeformed, i.e., entirely within the Middle Or-dovician Da 3/4 interval of �6 m.y. duration(interpolated from Gradstein and Ogg, 1996).While the olistostrome was forming, turbiditicflysch was also being deposited into large sub-marine fans, forming the Nyes Road Member.Whether all parts of the Lower Ordovician se-quence were fragmented and reincorporatedinto an olistostrome throughout the klippe isnot known. Throughout the Arenig and Llan-virn, pelagic red beds and cherts and associ-ated sediment also accumulated in areas distalto, and perhaps between, the submarine fans.

Third, a period of synorogenic turbiditicflysch sedimentation began in the Martinsburgforeland basin during the time of C. bicornisand early D. clingani Zones. As with the otherTaconic terranes of the Appalachians, the car-bonate platform foundered and was drownedin response to the tectonic loading during thisevent. Boulder conglomerates (wildflysch de-posits) developed in advance of the allochthonemplacement, although these deposits arescattered and not uniformly distributed. Fau-nal evidence suggests that the Hamburg klippewas emplaced in the time of the early D. clin-gani Zone, or slightly later, either as a coher-ent mass or in pieces.

The large size of the allochthon must haveoccupied a very significant part of the Mar-tinsburg foreland basin, diverting sediment toand around its fringe (Faill, 1997). Eventually,the klippe was covered by late Martinsburgdeposition during Edenian time (late Cara-doc), as revealed by the shelly fauna and grap-tolites (Climacograptus spiniferus Zone ofRiva, 1969, 1974) found at Swatara Gap (Ste-phens et al., 1982). No graptolite faunas be-tween upper C. bicornis or possibly lower D.clingani Zone through the C. spiniferus Zonehave been found. This represents the time in-terval when the presence of the allochthon di-verted deposition until the foreland basin filledon either side and its sediments finally over-lapped it.

TECTONIC SETTING

The Hamburg allochthon arrived in its cur-rent position relative to the lower Paleozoicstrata in this part of the Appalachians (Figs. 1and 2) during the Middle to Late Ordovician

Taconic orogeny (Stose, 1946). It arrived com-pletely detached from its original basementcrust and continental fringe. The possible re-lationship between the Hamburg sequence andother lower slope and basinal deposits of theWestminster terrane, which was also obductedonto the Laurentian margin in the nearbyPiedmont, was summarized by Faill (1997).This relationship is complicated and involvesthe configuration and sedimentation of theoceanic fringe with microcontinental and is-land-arc elements outboard of the Laurentianplatform. Faill (1997) suggested that an Oc-toraro sea developed and received sedimentfrom both Laurentia to the west and micro-continent(s) to the east. This scenario is sim-ilar in many respects to models proposed byThomas (1977), Lash et al. (1984), and Lashand Drake (1984). The imbrication of west-ward-obducted multiple terranes is the classicTaconic pattern that involved outboard islandarcs, drifted microcontinents, and intrabasinalsequences formed along the way (Rodgers,1971; Drake et al., 1989; van der Pluijm et al.,1995; Faill, 1997).

Faill (1997) described an Octoraro sea asseparating Laurentia from a microcontinentcomplex, termed the Baltimore-Brandywineterrane. Beyond this complex was the Theicocean and depositional basin to the east,which included an island arc, the WilmingtonComplex. According to Faill (1997), the Ham-burg klippe was a gravity detachment from theOctoraro sea sequence (some part of the West-minster terrane) lifted high on the Marticthrust (first suggested by Kay, 1941) afterwestward obduction. The depositional loca-tion of the Hamburg sequence within the Oc-toraro sea was not specified.

The contents of the Hamburg sequence dif-fer significantly from the Octoraro sea sedi-ments of the Westminster terrane. The Ham-burg klippe contains lithofacies anddepositional characteristics not present in theother Octoraro sea successions, such as abun-dant deep-water limestone facies; thick, oftenred, chert and cherty shale (commonly form-ing long mappable ridges); large masses ofamygdaloidal basalts, which were extrudedover limestone; diabase dikes in the area nearthe basalts; thin volcanic ash beds; and largeolistostromal complexes. The Octoraro se-quences contain thin scattered ocean-floor ba-salts (Smith and Barnes, 1994), but no suchcorresponding intrusions occur in the Ham-burg sequence. The dissimilarity of the Ham-burg sequence from the other Octoraro seasediments (the Westminster terrane) suggeststhat these two successions may have been de-posited in different depocenters or at different

times. However, because none of the other Oc-toraro sea sequences have been dated, no con-fident correlation between or among them canbe made. Volcanic ash beds in the Hamburgsequence also demonstrate an original locationin closer proximity to a volcanic source (Wil-mington Complex?) than the Westminster se-quence, which does not have such ash bedsreported.

Separated from, and south of, the Hamburgklippe is an area of shale and other clastic li-thologies mapped as the Cocalico Shale (Jonasand Stose, 1930). Stose (1946) included thelocalities in the Hamburg klippe, and Jonasand Stose (1930) reported poorly preserved,possible Middle Ordovician graptolites ofNormanskill type. Stose and Jonas (1927) andStose (1946) also classified a variety of purpleshale found in the Cocalico as being of tuff-aceous origin. Direct comparison of the Co-calico sequence with the Hamburg sequenceremains problematic. Just as with the West-minster terrane, the Cocalico sequence differssignificantly from the Hamburg sequence.How this terrane fits into the overall schemeof Octoraro sea, Theic ocean, or Martinsburgbasin components awaits further study.

Because the Hamburg klippe is now de-tached from its immediate provenance, its or-igin remains in the realm of speculation. Lashand Drake (1984) and Lash et al. (1984) pro-posed that the Hamburg sequence was depos-ited between a microcontinent and Laurentia.We support this hypothesis and envision aprocess of westward (present orientation) ob-duction and overthrusting that brought theHamburg sequence over westerly sourced Oc-toraro sea sediments.

CONCLUSIONS

1. The western portion of the Hamburgklippe is composed of an allochthonous bodyor bodies contained within the autochthonousMartinsburg Formation. The allochthon wasemplaced by gravity sliding during early-mid-dle Caradoc time (late C. bicornis to D. clin-gani Zones).

2. Flysch deposited in the Martinsburg fore-land in advance of the incoming allochthonmay be slightly older than other parts of theforeland basin and also contains scatteredwildflysch.

3. After emplacement, the allochthon oc-cupied a major portion of the Martinsburgforeland, which diverted incoming sedimentuntil it was finally buried and covered in thelate Caradoc (C. spiniferus Zone).

4. The contents of the western part of theallochthon (Hamburg klippe) are herein

Geological Society of America Bulletin, January 2001

NEW BIOSTRATIGRAPHIC INFORMATION FROM THE WESTERN PART OF THE HAMBURG KLIPPE

named the Dauphin Formation; there are threeinterfingering members. The pelagic ManadaHill Member (new) of early Arenig to middleLlanvirn (Da 3/4) age contains strata of redand tan shale, chert, and minor carbonate andvolcanic ash beds. The Shellsville Member(new) comprises fine-grained, variegated low-er slope and rise sediments of Da 3/4 age thatcontain faunally distinctive Lower Ordovicianolistoliths. One olistolith contains a nearlycomplete Tremadoc graptolite succession (andpossibly some late Cambrian strata), whereasother olistoliths contain strata of early andmiddle Arenig age. The Nyes Road Member(new) is also Da 3/4 age and is a submarinecanyon turbiditic flysch unit.

ACKNOWLEDGMENTS

We acknowledge the Natural Science and Engi-neering Research Council of Canada (NSERC) whoprovided funding to S.H. Williams for participationin this work. The Geological Survey of Canada atCalgary provided facilities and equipment duringpreparation of this paper. Lucian Platt generouslylent us his collection of graptolites from previouswork and John Riva provided his file of correspon-dence regarding earlier graptolite studies in theHamburg klippe. Sharon Lucisano drafted the fig-ures, and Benjamin Ganis typed the manuscript. Wealso acknowledge the useful comments of Avery A.Drake Jr. and Stig Bergstrom.

REFERENCES CITED

Bergstrom, S.M., Epstein, A.G., and Epstein, J.B., 1972,Early Ordovician North Atlantic province conodontsin eastern Pennsylvania: U.S. Geological Survey Pro-fessional Paper 800-D, p. D37–D44.

Berry, W.B.N., 1960, Graptolite faunas of the Marathonregion, west Texas: University of Texas Publication6005, 179 p.

Berry, W.B.N., 1962, Stratigraphy, zonation, and age ofSchagticoke, Deepkill, and Normanskill shales, east-ern New York: Geological Society of America Bul-letin, v. 73, p. 695–718.

Berry, W.B.N., 1970, Review of Late Middle Ordoviciangraptolites in eastern New York and Pennsylvania:American Journal of Science, v. 269, p. 304–313.

Berry, W.B.N., 1971, Late Ordovician graptolites fromsoutheastern New York: Journal of Paleontology, v.45, p. 633–640.

Bosworth, W., 1989, Melange fabrics in the unmetamor-phosed external terraces of the northern Appalachians,in Horton, J.W., and Rast, N., eds., Melanges and olis-tostromes of the U.S. Appalachians: Geological So-ciety of America Special Paper 228, p. 65–91.

Carswell, L.D., Hollowell, J.R., and Platt, L.E., 1968, Ge-ology and hydrology of the Martinsburg Formation inDauphin County, Pennsylvania: Pennsylvania Geolog-ical Survey Ground Water Report W24, 54 p.

Cooper, R.A., 1999, Ecostratigraphy, zonation, and globalcorrelation of earliest Ordovician planktic graptolites:Lethaia, v. 32, p. 1–16.

Cooper, R.A., Maletz, J., Haifeng, W., and Erdtman, B.-D.,1998, Taxonomy and evolution of earliest Ordoviciangraptoloids: Norsk Geologisk Tidsskrift, v. 77, p. 3–32.

Drake, A.A., Jr., Sinha, A.K., Laird, J., and Guy, R.E.,1989, The Taconic orogen, in Hatcher, R.D., Jr.,Thomas, W.A., and Viele, G.W., eds., The Appala-chian-Ouachita orogen in the United States: Boulder,Colorado, Geological Society of America, Geology ofNorth America, v. F-2, p. 101–177.

Epstein, J.B., and Berry, W.B.N., 1973, Graptolites fromthe Martinsburg Formation, Lehigh Gap, easternPennsylvania: U.S. Geological Survey Journal of Re-search, v. 1, no.1, p. 33–37.

Epstein, J.B., Epstein, A.G., and Bergstrom, S.M., 1972,Significance of Lower Ordovician exotic blocks in theHamburg klippe, eastern Pennsylvania: U.S. Geolog-ical Survey Professional Paper 800-D, p. D29–D36.

Faill, R.T., 1997, A geologic history of the north-centralAppalachians, Part 1, Orogenesis from the Mesopro-terozoic through the Taconic orogeny: American Jour-nal of Science, v. 297, p. 551–619.

Finney, S.C., 1980, Thamnograptid, dichograptid and abrograp-tid from the Middle Ordovician Athens Shale of Ala-bama: Journal of Paleontology, v. 54, p. 1184–1208.

Finney, S.C., and Skevington, D., 1979, A mixed Atlantic-Province Middle Ordovician graptolite fauna in west-ern Newfoundland: Canadian Journal of Earth Scienc-es, v. 16, p. 1899–1902.

Finney, S., Grubb, B., and Hatcher, R., Jr., 1996, Graphiccorrelation of Middle Ordovician graptolite shale,southern Appalachians: An approach for examiningthe subsidence and migration of a Taconic forelandbasin: Geological Society of America Bulletin, v. 108,p. 355–371.

Ganis, G.R., 1997, Notes on the Hamburg klippe: Biostra-tigraphy, ash layers, olistostromes, and exotics: Guide-book 16th Annual Harrisburg Area Geological SocietyField Trip, 52 p.

Gradstein, P.M., and Ogg, J., 1996, A Phanerozoic timescale: Episodes, v. 19, no.1 and 2, p. 3–5.

Gray, C., and Willard, B., 1955, Stratigraphy and structureof lower Paleozoic rocks in eastern Pennsylvania, inField guidebook of Appalachian geology, Pittsburghto New York, March 1955: Pittsburgh Geological So-ciety, p. 87–92.

Hughes, R.A., 1989, Llandeilo and Caradoc graptolites ofthe Builth and Shelve inliers: Palaeontographical So-ciety Monograph 141, 89 p.

Jonas, A.I., and Stose, G.W., 1930, Lancaster Quadranglegeology and mineral resources: Pennsylvania Topo-graphic and Geologic Survey Atlas 168, 106 p.

Kay, G.M., 1941, Taconic allochthon and the Martic thrust:Science, v. 44, p. 73.

Landing, E., 1986, Depositional tectonics and biostratigra-phy of the western portion of the Taconic allochthon,eastern New York State: The Canadian Paleontologyand Biostratigraphy Seminar: New York State Muse-um Bulletin 462, p. 96–110.

Lash, G.G., 1984, The Jonestown volcanic rocks, easternPennsylvania near-trench volcanism in the central Ap-palachians: Geological Society of America Abstractswith Programs, v. 16, p. 46.

Lash, G.G., and Drake, A.A., Jr., 1984, The Richmond andGreenwich slices of the Hamburg klippe in easternPennsylvania: Stratigraphy, sedimentology, structure,and plate tectonic implications: U.S. Geological Sur-vey Professional Paper 1312, 40 p.

Lash, G.G., Lyttle, P.T., and Epstein, J.B., 1984, Geologyof an accreted terrane: The eastern Hamburg klippeand surrounding rocks, eastern Pennsylvania: AnnualField Conference of Pennsylvania Geologists, 49th,Reading, Pennsylvania, guidebook: Harrisburg, Fieldconference of Pennsylvania Geologists, Inc., p. 1–73.

Lofgren, A., 1997, Conodont faunas from the upper Tre-madoc at Brattefors, south-central Sweden, and recon-struction of the Paltodus apparatus: GFF, v. 119, p.257–266.

Lofgren, A.M., Repetski, J.E., and Ethington, R.L., 1999,Some trans-Iapetus faunal connections in the Trema-docian, in Serpagli, E., ed., Studies on conodonts—Proceedings of the Seventh European Conodont Sym-posium: Bolletino della Societa PaleontologicaItaliano, v. 37, p. 159–173.

Maletz, J., 1997a, Arenig biostratigraphy of the Pointe-de-Levy slice, Quebec Appalachians, Canada: CanadianJournal of Earth Sciences, v. 34, p. 733–752.

Maletz, J., 1997b, Graptolites from the Nicholsonograptusfasciculatus and Pterograptus elegans Zones (Aber-eiddian, Ordovician) of the Oslo region, Norway:Greifswalder Geowissenschaftliche Beitrage, v. 4, p.5–98.

McBride, E.F., 1962, Flysch and associated beds of theMartinsburg Formation (Ordovician), Central Appa-lachians: Journal of Sedimentary Geology, v. 32, p.39–91.

Mitchell, C.E., and Maletz, J., 1994, Graptolite biostratig-raphy and age relations among the Middle OrdovicianTable Head and Goose Tickle groups, western New-foundland, Canada, in Fourth Canadian PaleontologyConference, Brock University, St Catherines, Ontario,September 23rd–25th: St. Catherine’s, Ontario, Pro-gram and Abstracts, p. 12.

Parris, D.C., and Cruikshank, K.M., 1992, Graptolite bio-stratigraphy of the Ordovician Martinsburg Formationin New Jersey and contiguous areas: New Jersey Geo-logical Survey Geological Survey Report 28, 18 p.

Platt, L.B., Loring, R.B., Papaspyros, A., and Stephens,G.C., 1972, The Hamburg klippe reconsidered: Amer-ican Journal of Science, v. 272, p. 305–318.

Raring, A.M., and Ganis, G.R., 1973, An occurrence ofconodont-bearing allochthonous carbonates in theMartinsburg Formation, Berks County, Pennsylvania:Geological Society of America Abstracts with Pro-grams, v. 5, p. 210.

Repetski, J.E., 1984a, Conodonts from the Greenwich sliceof the Hamburg klippe near Greenawald, Pennsylva-nia, in Lash, G.G., et al., eds., Geology of an accretedterrane: The eastern Hamburg klippe and surroundingrocks, eastern Pennsylvania: Annual Field Conferenceof Pennsylvania Geologists, 49th, Reading, Pennsyl-vania, guidebook: Harrisburg, Field conference ofPennsylvania Geologists, Inc., p. 92.

Repetski, J.E., 1984b, Conodonts from Spitzenburg, inLash, G.G., et al., eds., Geology of an accreted ter-rane: The eastern Hamburg klippe and surroundingrocks, eastern Pennsylvania: Annual Field Conferenceof Pennsylvania Geologists, 49th, Reading, Pennsyl-vania, guidebook: Harrisburg, Field conference ofPennsylvania Geologists, Inc., p. 94.

Riva, J., 1969, Middle and Upper Ordovician graptolite fau-nas of St. Lawrence Lowlands of Quebec, and AnticostiIsland, in Kay, M., ed., North Atlantic—Geology andContinental Drift, a symposium:American Associationof Petroleum Geologists Memoir 12, p. 513–556.

Riva, J., 1972, Geology of the Environs of Quebec City:Montreal, International Geological Congress, 24th,Guidebook, 53 p.

Riva, J., 1974, A revision of some Ordovician graptolites ofeastern North America: Palaeontology, v. 17, p. 1–40.

Rodgers, 1971, The Taconic orogeny: Geological Societyof America Bulletin, v. 82, p. 1141–1178.

Rogers, H.D., 1858, The geology of Pennsylvania, Volume1: Philadelphia, Pennsylvania, J.B. Lippincott and Co.,586 p.

Root, S.I., 1977, Geology and mineral resources of the Har-risburg west area, Cumberland and York counties,Pennsylvania: Pennsylvania Topographic and Geolog-ic Survey Atlas 148ab, 106 p.

Root, S.I., and MacLachlan, D.B., 1978, Western limit ofTaconic allochthons in Pennsylvania: Geological So-ciety of America Bulletin, v. 89, p. 1515–1528.

Ross, R.J., Jr., Hintze, L.F., Ethington, R.L., Miller, J.F.,Taylor, M.E., and Repetski, J.E., 1997, The Ibexian,lowermost series in the North American Ordovician:U.S. Geological Survey Professional Paper 1579-A,115 p.

Ross, R.J., et al., 1982, The Ordovician System in the Unit-ed States; correlation chart and explanatory notes: In-ternational Union of Geological Sciences Publication12, 73 p.

Smith, R.C., II, and Barnes, J.H., 1994, Geochemistry andgeology of metabasalt in southeastern Pennsylvania,in Faill, R.T., and Sevon, W.D., eds., Various aspectsof Piedmont geology in Lancaster and Chester coun-ties, Pennsylvania: Annual Field Conference of Penn-sylvania Geologists, 59th, Lancaster, Pennsylvania,guidebook: Harrisburg, Field conference of Pennsyl-vania Geologists, Inc., p. 45–72.

Stephens, G.C., Wright, T.O., and Platt, L.B., 1982, Geol-ogy of Middle Ordovician Martinsburg Formation andrelated rocks in Pennsylvania: Annual Field Confer-ence of Pennsylvania Geologists, 47th, New Cumber-

Geological Society of America Bulletin, January 2001

GANIS et al.

land, Pennsylvania, guidebook: Harrisburg, Field con-ference of Pennsylvania Geologists, Inc., 87 p.

Stose, G.W., 1946, The Taconic sequence in Pennsylvania:American Journal of Science, v. 244, p. 665–696.

Stose, G.W., and Jonas, A.I., 1927, Ordovician shale andassociated lava in southeastern Pennsylvania: Geolog-ical Society of America Bulletin, v. 38, p. 505–536.

Stouge, S., and Bagnoli, G., 1988, Early Ordovician co-nodonts from Cow Head peninsula, western New-foundland: Palaeontographia Italica, v. 75, p. 89–179.

Taylor, R.S., 1997, Taxonomy and biostratigraphy of Mid-dle Ordovician (Llanvirn) graptolites from the TableCove and Black Cove formations, western Newfound-land [M.S. thesis]: St. John’s, Memorial University ofNewfoundland, 258 p.

Thomas, W.A., 1977, Evolution of the Appalachian-Ouach-ita salients and recesses from reentrants and promon-tories in the continental margin: American Journal ofScience, v. 277, p. 1233–1278.

Vandenberg, A.H.M., and Cooper, R.A., 1992, The Ordo-vician graptolite sequence of Australasia: Alcheringa,v. 16, p. 33–85.

van der Pluijm, B.A., Van der Voo, R, and Torsvik, T.H.,1995, Convergence and subduction at the Ordovicianmargin of Laurentia, in Hibbard, J.P., van Staal, C.R.,and Cawood, P.A., eds., Current perspectives in theAppalachian-Caledonian orogen: Geological Associa-tion of Canada Special Paper 41, p. 127–136.

Willard, B., 1943, Ordovician clastic sedimentary rocks inPennsylvania: Geological Society of America Bulle-tin, v. 54, p. 1067–1122.

Williams, H., compiler, 1978, Tectonic lithofacies map ofthe Appalachian orogen: St. John’s, Memorial Uni-versity of Newfoundland, scale 1:1 000 000.

Williams, S.H., 1992, Lower Ordovician (Arenig–Llanvirn)graptolites from the Notre Dame subzone, centralNewfoundland: Canadian Journal of Earth Sciences,v. 29, p. 1717–1733.

Williams, S.H., 1995, Middle Ordovician graptolites fromthe Lawrence Harbour Formation, central Newfound-land, Canada: Palaeontographica, v. 235, p. 21–77.

Williams, S.H., and Stevens, R.K., 1988, The Lower Or-dovician (Arenig) graptolites of the Cow Head Group,western Newfoundland: Palaeontographica Canadiana,v. 5, 167 p.

Williams, S.H., and Stevens, R.K., 1991, Late Tremadocgraptolites from western Newfoundland: Palaeontolo-gy, v. 34, p. 1–47.

Wright, T.O., and Stephens, G.C., 1978, Regional implica-tions of the stratigraphy of Shochary Ridge, Berks andLehigh counties, Pennsylvania: American Journal ofScience, v. 278, p. 1000–1017.

Wright, T.O., Stephens, G.C., and Wright, E.K., 1979, Arevised stratigraphy of the Martinsburg Formation ofeastern Pennsylvania and paleogeographic conse-quences: American Journal of Science, v. 279, p.1176–1186.

Zen, E-An, 1968, Nature of the Ordovician orogeny in theTaconic area, in Zen, E-AN, White, W.S., Hadley,J.B., and Thompson, J.B., eds., Studies of Appala-chian geology: Northern and Maritime: New York, In-terscience Publishers.

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