Geoarchaeology and Paleoenvironmental Context of the Burntwood Creek Rockshelter, High Plains of...

Research Article

Geoarchaeology and Paleoenvironmental Context of theBurntwood Creek Rockshelter, High Plains of NorthwesternKansas, U.S.A.Laura R. Murphy* and Rolfe D. Mandel

Kansas Geological Survey, University of Kansas, Lawrence, Kansas

Correspondence*Corresponding author;

E-mail: [email protected]

Received27 October 2011

Accepted26 January 2012

Scientific editing by Jamie Woodward

Published online in Wiley Online Library

(wileyonlinelibrary.com).

doi 10.1002/gea.21412

The first systematic geoarchaeological study of a rockshelter in Kansas yieldedinformation about rockshelter formation, Holocene paleoenvironments, ar-chaeological site formation processes, and prehistoric human habitation andsite use. The rockshelter was carved by groundwater sapping; colluvium, al-luvium, and roof-fall debris subsequently accumulated on its floor. An assem-blage of Late Archaic (∼2000–4000 14C years before present [yr B.P.]) culturaldeposits (lithic material, bone, and charcoal) is preserved in a 2-m thick pack-age of colluvium and alluvium in front of the shelter. Chipped stone analysisindicates that Late Archaic occupants of the shelter were using mostly localmaterials and resharpening their stone tools at the shelter. Stable carbon iso-tope and phytolith analyses indicate that a mixed C3 and C4 plant communityexisted in the study area and that it changed in composition through the lateHolocene. Based on the phytolith assemblage from an unlined fire pit at thefront of the shelter, Late Archaic people used local hackberry trees for fueland/or food. C© 2012 Wiley Periodicals, Inc.

INTRODUCTION

The search for Paleoindian and Archaic archaeologicalsites on the High Plains of western Kansas has focusedmostly on alluvial terraces in stream valleys (Mandel,1992, 1995, 2006). One deeply stratified Early Paleoin-dian site (Mandel, Holen, & Hofman, 2005) and a fewLate Archaic sites (Mandel, 2012) have been recorded,but the pre-Ceramic archaeological record has remainedelusive (see Table I for the cultural chronology). Thepaucity of recorded Paleoindian and Archaic sites on theHigh Plains is attributed to lack of visibility due to deepburial or to removal by stream erosion (Mandel, 1995,2006; Mandel, Holen, & Hofman, 2005). In other words,cultural deposits in open-air alluvial settings are proneto the effects of geomorphic processes (Mandel, 2008;Beeton & Mandel, 2011).

Rockshelters in western Kansas have great potentialfor containing stratified cultural deposits, but have notreceived much attention from archaeologists. In general,rockshelters are important sedimentary and environmen-tal archives (Woodward & Goldberg, 2001) that holdrecords of local landscape evolution, site formation pro-cesses, and paleoenvironments because they are sediment

traps protected from erosion, and archaeological mate-rials are often sealed under roof-fall blocks (Goldberg &Mandel, 2008). Also, autochthonous and allocthonoussediment can fill and seal rockshelters and their archaeo-logical deposits relatively quickly (Collins, 1991; Farrand,2001a). Despite shorter lifespans compared to caves, eth-noarchaeological research has demonstrated that rock-shelters were long-term focal points of hunter-gathereractivities such as tool maintenance, food processing, andcooking (Binford, 1978; Gorecki, 1991; Walthall, 1998).Hence, rockshelters can be singularly important archivesof prehistoric human ecology and culture history (e.g.,Martin et al., 1993; Abbott, 1997; Kourumpas et al.,2009).

North American rockshelters such as Rodgers Shel-ter in west-central Missouri (Wood & McMillan, 1976),Meadowcroft Shelter in Pennsylvania (Donahue &Adovasio, 1990), and Bonneville Estates Rockshelterin Nevada (Goebel, 2003) have yielded well-preservedarchaeological materials that typically represent multi-ple and/or seasonal occupations. Many rockshelters andcaves have been investigated in the Black Hills of westernSouth Dakota (Over, 1936; Weston, 1982; Martin et al.,

344 Geoarchaeology: An International Journal 27 (2012) 344–362 Copyright C© 2012 Wiley Periodicals, Inc.

MURPHY AND MANDEL THE BURNTWOOD CREEK ROCKSHELTER RECORD, NW KANSAS

Table I Cultural chronology for the Central Plains of North America.

Cultural Periods Ages, 14C yr B.P.a

Ceramic 200–2000

Late Archaic 2000–4000

Middle Archaic 4000–6000

Early Archaic 6000–9000

Paleoindian 9000–11,600

aAges are approximate (Hoard & Banks, 2006).

1993), a region where Cretaceous–Paleogene limestonehas undergone extensive dissolution. Comparatively lit-tle, however, is known about rockshelters formed in theMiocene–Pliocene Ogallala Formation of the High Plains.Only a few rockshelters or caves have been studied onthe High Plains in Nebraska (Bell & Cape, 1936; Palmeret al., 2010), Colorado (Wood, 1967; Tate, 1999), and Ok-lahoma (Lintz & Zabawa, 1984). Prior to our study of theBurntwood Creek Rockshelter, none of the 34 prehistoricrockshelter and cave sites in Kansas (Kansas State Histor-ical Society, 2008) has been studied in detail.

The Burntwood Creek Rockshelter formed in the cal-crete escarpment of the Ogallala Formation on the westside of Burntwood Creek valley in northwestern Kansas(Figures 1, 2a,b). The rockshelter is within sight of a largebone bed (site 14RW2) (Figure 2c), a Late Paleoindianbison jump believed to be associated with the Allen tech-nological complex that dates to ca. 9500–8500 14C yearsbefore present (yr B.P.) (Russell & Hofman, 2006). Initialtests at the rockshelter revealed archaeological materialsuch as bone, charcoal, and chipped stone recovered fromthree shallow 1 × 1 m test excavations (Stein, 2005) (Test1–3 in Figure 3a). Thus, in an effort to find Paleoindiancultural deposits in a stratified context, we launched a de-tailed investigation of the Burntwood Creek Rockshelterbecause it seemed likely the people responsible for theLate Paleoindian bison kill inhabited the rockshelter.

Although archaeological testing in the shelter did notrecord any definitive Paleoindian artifacts, stratified LateArchaic cultural deposits occur in the fill at the frontof the rockshelter. Our investigation yielded informationabout how the rockshelter formed and retreated throughtime, the subsistence and lithic procurement strategies ofLate Archaic people who occupied the shelter, the siteformation processes that affected the cultural deposits,and the environmental conditions during the period ofoccupation.

ENVIRONMENTAL SETTING

The Burntwood Creek Rockshelter is located inRawlins County, Kansas, along Burntwood Creek(39◦56′05.35′ ′N, 101◦21′35.06′ ′W), a low-order inter-

mittent S-N flowing stream in the Republican Riverbasin (Figure 1). The locality is within the High Plainssubprovince of the Great Plains physiographic province(Fenneman, 1931). The High Plains developed whenclastic sediments were shed from the Rocky Mountainsand transported eastward during the Miocene andearliest Pliocene, forming an extensive plain of sand andgravel (Frye & Leonard, 1952; Buchanan, 1984; Ludvig-son et al., 2009). The Ogallala Formation is comprised ofthese coarse-grained sediments (Merriam, 1963). Thereare many strongly indurated petrocalcic horizons in theOgallala Formation; the most distinct of these horizons isthe resistant “caprock” caliche that forms the surface ofthe Ogallala (Reeves, 1976). The caprock is several me-ters thick, preserving the plateau topography of the HighPlains. Springs occur along the High Plains escarpmentand where the Ogallala Formation, a major aquifer, isexposed in the walls of stream valleys (Mandel, 2006).In northwestern Kansas, the High Plains is mantledby Quaternary loess, and where the loess is dissectedexposures of the underlying Ogallala caprock occur.

The climate of northwestern Kansas is semiarid andcharacterized by hot summers and cold winters (Man-del, 2006). Average summer and winter temperaturesare 18.7◦C and 3.3◦C, respectively, and the mean annualprecipitation is 52.8 cm (High Plains Regional ClimateCenter, 2011).

The study area has a drought-resistant short-grass com-munity of blue grama (Bouteloua gracilis) and buffalograss (Buchloe dactyloides), and a mixed-grass prairie com-munity of big bluestem (Andropogon gerardii) and littlebluestem (Schizachyrium scoparium). Prickly pear (Oputinasp.) and yucca (Yucca glauca) are also present (Wedel,1986). Riparian trees include cottonwood (Populus del-

toides), black willow (Salix nigra), and hackberry (Celtisoccidentalis) (Kuchler, 1974; Lauver et al. 1999; USDANRCS, 2010) (Figure 2c).

RECORDED SITES IN BURNTWOOD CREEKVALLEY

Four archaeological sites have been recorded alongBurntwood Creek near the rockshelter: 14RW2, 14RW3,14RW4, and 14RW5 (Figure 1a; Stein, 2005). Sites14RW4 and 14RW5 have not yet been excavated, butchipped stone scatters occur on the land surface at bothsites. Site 14RW2, the Late Paleoindian bison jump, isa thick accumulation of Bison antiquus bones (Russell& Hofman, 2006). A Late Paleoindian “Allen” projectilepoint was found in the bone bed. Murphy and Man-del (2007) reported radiocarbon ages of 8880 ± 25 and9220 ± 25 yr. B.P. determined on charcoal associated

Geoarchaeology: An International Journal 27 (2012) 344–362 Copyright C© 2012 Wiley Periodicals, Inc. 345

THE BURNTWOOD CREEK ROCKSHELTER RECORD, NW KANSAS MURPHY AND MANDEL

Figure 1 (a) Modified Google Earth image of the Burntwood Creek locality showing five recorded archaeological sites (imagery date: 16 March 2006).

The black dots represent locations of permanent data benchmarks set between 2006 and 2007. The inset map shows the location of the Burntwood

Creek Rockshelter in northwestern Kansas in relation to surrounding states. (b) Illustration showing the general rockshelter fills from A-A′ (a) and the

approximate location of Trenches 1 and 3A. The illustration is not to scale.

with bone in the “south gully,” or the southern extentof the bone bed (Figure 1a, Table II). Site 14RW3 con-tains many fragments of bison bone that represent a killor butchering site of unknown relationship to 14RW2.

Approximately 3 km to the north and east ofthe Burntwood Creek Rockshelter are sites 14RW419,14RW420, and 14RW421, all of which are chipped stonesurface scatters of unknown cultural affiliation (see Stein,

2005). One additional site, 14RW417, contains an iso-lated Late Archaic or Early Ceramic projectile point.

MULTIPLE PROXIES

Multiple lines of evidence are necessary to assess siteformation processes and reconstruct paleoenvironments



Figure 2 Photographs of the Burntwood Creek

Rockshelter and surrounding landscape. (a) View to the

west of the rockshelter from above. Note the pour-off

at the top of the shelter roof. (b) The Burntwood Creek

Rockshelter formed in the Ogallala formation. View is to

the northwest. (c) The surrounding landscape from the

top of the rockshelter, with a view of the Late

Paleoindian bison jump (14RW2) to the east.

in rockshelters because of the many potential sedimentsources, and the post-depositional processes that can al-ter the record. In this study, we use pedologic and litho-logic description, grain-size analysis (pipette and Ro-Tap R© methods), optical cathodoluminescence (CL) andepifluorescence (EF) microscopy, stable carbon isotopes,and phytoliths. Traditional characterization of grain sizesis important for determining sediment source and trans-port, as well as depositional history (Hassan, 1978; Man-del & Simmons, 1997; Woodward & Bailey, 2000; Far-rand, 2001a,b; Kourumpas et al., 2009), but grain-sizeanalysis alone is not enough for a robust interpretationof past environments (Mandel & Simmons, 1997).

Stable carbon isotope ratios determined on pedogeniccarbon (Boutton, 1996) paired with the extraction ofphytoliths, or “plant stones” (Piperno, 2006), from soilsand sediments has proved effective for paleoenvironmen-tal reconstruction (Fredlund & Teiszen, 1997; Kelly et al.,1998; Cyr et al., 2011). Changes in the relative propor-tions of C3 versus C4 species inferred from the δ13C val-ues on soil organic matter (SOM) can be compared to thephytolith data, and inferences can be made about the in-put of carbon from C3 trees and shrubs that are under-represented in the phytolith record (Fredlund & Tieszen,1997; Piperno, 2006). Specific phytolith differentiationamong the major grass subfamilies (e.g., Chloridoideae,Panicoideae, Pooideae) allows a more-refined assessmentof the stable carbon isotope data. Because C4 warm/moistpanicoids and C4 warm/dry chloridoids can be differen-tiated based on phytolith morphotypes, more precise pa-leoenvironmental assessments can be made compared tothe broad trends in stable carbon isotope values alone.

CL and EF microscopy is used in sedimentary geol-ogy to infer carbonate formation, paleohydrologic pro-cesses, and post-depositional sediment overprinting (cf.Meyers, 1974; Ten Have & Heijnen, 1985; Ludvigson,1989; Bruckschen, Neuser, & Richter, 1992; Habermann,Neuser, & Richter, 1998; McGarry & Baker 2000; Boggs &Krinsley, 2006; Rainey & Jones, 2007). These techniquescan strengthen interpretation better than lithologic de-scription and grain-size analysis alone. CL provides theability to analyze diagenesis of carbonate sedimentaryrocks, such that reducing phreatic environments will pro-duce a bright orange image due to manganese previouslystable in solution (Boggs & Krinsley, 2006). With the EFtechnique, organic acids that assimilate in the carbonatematrix are brightly reflected, and organic acids that havebeen subjected to digenesis will reflect with less inten-sity (Rainey & Jones, 2007). The EF method is usefulfor determining primary depositional fabrics of carbon-ates that have been subjected to overprinting (Rainey &Jones, 2007).

METHODS

In 2007, three backhoe trenches were excavated at theBurntwood Creek Rockshelter (Figure 3a). In order toprevent destruction of cultural resources, trenching wascarefully monitored by archaeologist Jack Hofman andus. Cultural materials encountered during trenching wererecorded with a total station and collected. Trench 1 was∼18 m long, 1.5 m wide, and 2.5 m deep (Figures 1b,3b). Care was taken to leave a hearth feature and lithic



Figure 3 (a) Contour map of the Burntwood Creek Rockshelter modified from Stein (2005). The map shows Test Units 1–3 excavated by Stein (2005),

Trenches 1, 2, 3A, and 3B, and archaeological excavation units A–D. (b) A portion of the North wall in Trench 1 showing sedimentary Units I-VII. (c) Soil

profile (north wall) from Trench 3A showing soil horizons.

material intact within the walls of the Trench 1. Trench2 was cut perpendicular to Trench 1, but collapsed. Deer(Odocoileus sp.) bone fragments and lithic material wererecovered and recorded ∼1.5 m below the Trench 2 sur-face prior to collapse. Trench 3A was 2 m long, 2 m wide,and 1.56 m deep (Figures 1b, 3c). Trench 3B was 2 m longand 2 m wide, and was terminated at a depth of 75 cmwhen large blocks of roof-fall were encountered. Deeperbackhoe excavation was ceased because the groundwatertable was intercepted and unstable conditions created bythe inflow of water could have caused the trench to col-

lapse. Trench walls were cleaned with trowels to revealfresh sediment for sampling. Four 1 × 1 m archaeologi-cal excavation units were established adjacent to Trench1 where the backhoe exposed cultural materials in thewall.

Three ∼30-cm-wide soil/sediment profiles were sam-pled from the north wall of Trench 1 every 10 cm fromthe land surface to a maximum depth of 220 cm (Fig-ure 4). The samples were collected for stable isotope, phy-tolith, and grain-size analyses. A fourth profile was sam-pled for grain-size analysis from the west wall of Trench



Table II Radiocarbon ages from Trenches 1 and 3A at the rockshelter (14RW418) and the “south gully” of the Late Paleoindian bison bone bed (14RW2).

Site Material Dating Depth Unit/ Calibrated

Number Location assayed Method (cm)a Soil δ13C 14C age yr. BP Lab. No. Age

14RW418 Trench 1 Charcoal AMS 100 IV −25.9 1930 ± 30 ISGS-A0859 1873 ± 30

14RW418 Trench 1 Bone AMS 200 IV −7.8 2230 ± 30 ISGS-A0867 2251 ± 59

14RW418 Trench 1 Feature 1 Charcoal AMS 70–74 V NR 2250 ± 20 UCI-41885 2278 ± 54

14RW418 Trench 1 Feature 1 Charcoal AMS 90 IV NR 2205 ± 20 UCI-41886 2226 ± 52

14RW418 Trench 1 Feature 2 Charcoal AMS 95–100 IV NR 2315 ± 20 UCI-41887 2336 ± 8

14RW418 Trench 1 Feature 2 Charcoal AMS 100–105 IV NR 2235 ± 20 UCI-41888 2252 ± 56

14RW418 Trench 1 Charcoal AMS 150–160 IV NR 2285 ± 30 UCI-41889 2317 ± 35

14RW418 Trench 3A SOM C 54–64 Soil 2 −22.1 710 ± 70 ISGS-6125 661 ± 45

14RW418 Trench 3A SOM C 93–103 Soil 3 −15.7 114.9 ± 0.5 ISGS-6199 138 ± 67

14RW418 Trench 3A SOM C 116–126 Soil 4 −20.4 102.4 ± 0.5 ISGS-6126 127 ± 79

14RW2 “South gully” Charcoal AMS 200 NR 8880 ± 25 UCI-41891 10,024 ± 60

14RW2 “South gully” Charcoal AMS 322 NR 9220 ± 25 UCI-41890 10,373 ± 60

aDepths are presented as centimeters below surface.

SOM: soil organic matter; C: conventional dating; NR: not reported.

Figure 4 Trench 1 north wall profile showing sedimentary units, profiles, and AMS 14C ages. Note that profile 4 was taken from the west wall of the

trench.

1 to a depth of 250 cm (Figure 5). A secondary carbon-ate mass was sampled from the lower half of Profile 4.Two thin sections from the top and bottom of the car-bonate mass were polished, scanned under transmittedlight, analyzed with a petrographic microscope, and thenbombarded with electrons using optical CL and EF tech-niques. In Trench 3A, soil samples were collected every10 cm for stable isotope, phytolith, and grain-size analy-ses. Trench 3B had a similar soil profile as Trench 3A, soit was described but not sampled.

Sedimentary units in the trenches were identified onthe basis of lithologic characteristics. Roman numeralsdesignate the sedimentary units, beginning with Unit I

at the bottom of each section. Soils were described usingMunsell color charts and standard terminology presentedby Soil Survey Staff (1993) and Birkeland (1999).

Four 1 × 1 m archaeological test units were excavatedby hand adjacent to Trench 1 (Units A–D, Figure 1b) in2007. Bone, charcoal, and chipped stone were mappedwith a total station and collected. Sediment from UnitsA through D was passed through 1/4- and 1/8-inch (6.4and 3.2 mm) screens, and all cultural materials were col-lected, washed, cataloged, and curated at the Archaeolog-ical Research Center, Biodiversity Institute, University ofKansas. A total of 281 pieces of chipped stone were ana-lyzed, which includes a sample of mapped lithic material



Figure 5 Soil profile and sand distribution from thewest end of Trench 1 (profile 4). A carbonatemasswas sampled from∼1.5 to 1.7mbelow themodern

surface. (a) CL image of carbonate mass thin section. (b) Plain-polarized light (PPL) image showing grains with calcite coatings. (c) EF image showing

brightly lit (red) organic acids surrounding previously deposited grains. Calcite coatings around crystal grains are also brightly lit.

(n = 265) associated with Feature 2 in Unit B. Feature 2exhibited the highest density of chipped stone at the site.The remaining sample (n = 16) includes the recorded ar-tifacts encountered during trenching (n = 8) and thosefrom Feature 1 (n = 8).

Five charcoal samples from Trench 1 were dated atthe University of California-Irvine (UCI), W.M. KeckCarbon Cycle AMS Laboratory. Also, the Illinois StateGeological Survey (ISGS) dated one charcoal sample andone bone sample from Trench 1, and three soil samplesfrom Trench 3A were assayed by conventional radiocar-bon dating of SOM. The radiocarbon ages are presentedin uncalibrated 14C yr B.P. in the text, and uncalibratedand calibrated 14C yr B.P. in Table II.

The pipette method was used to determine texture onparticle sizes less than 2000 μm (USDA NRCS, 2004). Theparticle size fractions are as follows: 2000–50 μm (totalsand), 50–2 μm (total silt), and <2 μm (total clay). Sam-ples consisting of ∼90% sand were analyzed separatelyfrom the pipette procedure with a Ro-Tap R© sieve shaker.The sand fractions are as follows: 63–88 μm (very finesand), 88–250 μm (fine sand), 250–707 μm (medium

sand), 707–1410 μm (coarse sand), and 1410–2000 μm(very coarse sand). Soil Survey Staff (1993) terminologywas used to describe the resulting texture.

Seventy-five samples from four profiles were pre-treated (decalcified) for stable carbon isotope analysis atthe Kansas Geological Survey. Raw δ13C values were ob-tained via high-temperature combustion with a CostechECS4010 elemental combustion system in conjunctionwith a ThermoFinnigan MAT253 isotope ratio mass spec-trometer at the Keck Paleoenvironmental & Environ-mental Stable Isotope Laboratory (KPESIL), Universityof Kansas. International standards were used to calibrateδ13C values. A precalibrated internal standard (DORM-2 dogfish muscle; National Research Council of Canada)was used in the δ13C calibration curve, as well as forpercent carbon (%C) determination. The precision of re-ported δ13C values is based on a linear correction of ob-served values versus expected values of the standards.Typical standard calibration curves yield an R2 of 0.9994or greater.

Sixteen soil and sediment samples from Trenches1 and 3A were processed for phytoliths following



methods outlined by Piperno (2006). Two lycopodiumspore tablets, each containing 18,585 spores, were addedto each sample to calculate phytolith concentration (phy-toliths per gram of pretreated sediment) (Cyr et al., 2011).Plant species nomenclature follows the PLANTS Database(USDA, 2010). Grass phytoliths are presented by threedominant subfamilies: Pooideae, Panicoideae, and Chlori-doideae (Brown, 1984; Fredlund and Teiszen, 1994). Di-cots, elongate cells, and phytolith concentrations also areincluded in the results following methods of Twiss, Suess,& Smith (1969) and Brown (1984).

RESULTS

Front of the Burntwood Creek Rockshelter

Lithology

Seven major sedimentary units were identified at thefront of the rockshelter in Trench 1 (Figure 4). Unit Iconsists of stratified parallel and cross-bedded sands (Fig-ure 5, Table III). Cross-strata dip ∼25◦ from the backof the shelter to the east. A discontinuous 20-cm-thicklayer of calcium carbonate is present 1.1–1.3 m belowthe top of Unit I (Figure 5). This carbonate unit in-corporates silicate sands from above and below. Petro-graphic CL imaging indicated manganese-activated CL inthe calcite (Figure 5a). EF petrography of the carbonateshowed significant heterogeneity in emitted light inten-sity, indicating variability in the purity of the carbonatemass (Figure 5c). Brightly lit organic acids in pore flu-ids surround large crystal grains, and thin calcite coat-ings surround many clasts (Figure 5b). Units II, III, V,and VII contained unsorted, nonimbricated fine gravel tocobble-sized weathered clasts of Ogallala Group sedimen-tary rocks (Table IV). Unit IV is a well-sorted silt loamdeposit that thickens to the east. Grain-size data from thethickest section of Unit IV exhibit three upward-fining se-quences indicated by increases in clay and silt accompa-nied by decreases in sand (Table IV).

Stable isotopes

The δ13C values from Profiles 1 and 2 in Trench 1 (Fig-ure 6) generally reflect a typical C3 plant community.The δ13C values are 1–2‰ higher from the base to thetop of both profiles, indicating a general increase in theproportion of C4 plants. However, the δ13C values tendto vary, trending toward more negative δ13C values inUnit V, the unit containing an unlined fire pit or hearthfeature. The C content is high in the surface soil and de-creases abruptly with depth (Figure 6).

The δ13C values from Profile 3 in Trench 1 varythroughout the profile. The maximum and minimum val-ues are offset by ∼3‰ (Figure 7). In general, δ13C valuesaverage –20‰. The peak C value of 0.6% is at the top ofthe profile and C content generally decreases with depth.

Phytoliths

The phytolith data for Profile 1 have three trends (Fig-ure 8). First, C3 pooids dominate in Unit I, coincidingwith low δ13C values. Second, Units II and III exhibit alarge increase in C4 chloridoids, indicating increased arid-ity that is not well represented in the δ13C data. Third,hackberry fruit (9%) and leaf phytoliths (20%) appear inUnits IV and V. More broken phytoliths and unidentifiedshort cells occur in Units I and II compared to the otherunits in Trench 1.

In Profile 3, phytoliths were extracted from the bottomand top of Unit V only (Figure 7). The bottom sample(185–195 cm) produced a grass assemblage consisting ofa relatively equal number of pooids and chloridoids withfew panicoids. At 40–50 cm, C4 chloridoids are dominant.The phytolith assemblage from 185 to 195 cm corrobo-rates δ13C values, but the phytoliths from 40 to 50 cmdo not closely correlate with δ13C values. Dicot cells aremore abundant in the bottom sample than the top.

Archaeology

We recorded two unlined hearth features (Features 1 and2) in archaeological units A and B adjacent to Trench 1(Figures 1b, 3a). Feature 1 in Unit V contained burnedhackberry seeds, charcoal, chipped stone, and bone frag-ments. Feature 2 in Unit IV contained chipped stone, bi-son elements, and deer- and bison-sized bone, includingone right bison maxilla with the full tooth row (P2-M3).Two retouched flakes, one of which was burned, werefound directly under the third molar (M3). Five layersof charcoal exposed 1.0–1.3 m below the land surfacewere separated by thin layers of silt and contained largeamounts of chipped stone and burned deer and bisonbone fragments. One layer of charcoal in the north wall ata depth of 1.5 m was not associated with cultural material(Figure 4).

Six lithic types were identified from the total sampleanalyzed (n = 281): fossilized wood (40.6%), Niobrarajasper (28.8%), quartz (10.3%), quartzite (8.2%) opal-ized Ogallala caliche (5.7%), and Hartville chert (4.3%).The material of six specimens (2.1%) could not be iden-tified (Table V). Nearly 95% of the sample is debitage,and the remaining ∼5% consists of tools, utilized flakes,preforms, or tested Ogallala cobbles (Table V).



Table

IIISo

ildescriptio

nforprofile4inTren

ch1(fron

tofthe

shelter).

Dep

thSo

ilMun

sell

Lower

(cm)

Horizon

Color

Texture

Structure

Roo

tsPores

Con

centratio

nsCon

sisten

cyBou

ndary

Other

Profile4

D,M

0–20

A10

YR5/2,

4/2

VGRSL

1fsbk–

1fgr

mv1

,1,&

3;c2

cv1&1;

m,TU

FRCS

Com

mon

krotov

ina3–

5cm

in

diameter

20–3

5Bk

10YR

6/3,

5/3

GRSL

v1fsbk

cv1&1;

f2&3

c,TU

m1&2Kfi;cv1KT

FRGS

35–4

0BCk

10YR

6/35/3

GRLS

v1sbk

cv1&1

cv1&1

m1&2Kfi;cv1KT

FRGS

40–6

0Ck1

10YR

6/4,

5/4

FGRLS

m–sg

cv1&1

cv1&1

cv1KT;c1D5Y

5/4mo

FRAW

Stratifi

ed

60–7

3Ck2

2.5Y

6/4,

5/4

CBLS

m–sg

cv1&f;f2

&3

cv1&1

fv1KT;c1D5Y

5/4,

2.5Y

6/6&6/8mo

FRAW

73–8

8Ck3

10YR

6/4,

5/4

GRS

m–sg

fv1&1

cv1&1;

c,TU

f1&2KT

FRAS

Fewlenses

ofsiliceo

usgravel

88–9

9C1

10YR

6/4,

5/4

FGRS

m–sg

fv1&1

cv1&1

c1D5Y

5/4mo

FRAS

Stratifi

ed,interbed

ded

with

fine

siliceo

usgravel

99–1

09C2

10YR

6/6,

5/6

Sm–sg

fv1&1

cv1,

f1FR

AS

109–

140

C3

10YR

6/4,

5/4

GRS

m–sg

fv1&1

cv1,

f1c1F10

YR5/6&5Y

6/6

FRAW

140–

154

C4

2.5Y

5/4,

5/3

Sm–sg

fv1

fv1&1

FRAW

Stratifi

ed

154–

168

C5

2.5Y

7/3,

6/3

CBFS

mfv1

FIAI

70%Carbon

atebyvo

lume

168–

185

C6

2.5Y

5/4,

6/6

FSm–sg

fv1&1

c1D2.5Y

6/6mo

FIAS

Stratifi

ed;cross-bed

ded

185–

205

C7

5Y6/3,

5/3

Sm

–f1

&2

FIAS

205–

250

C8

10YR

6/4,

5/4

Sm–sg

–f1

&2

c1F2.5Y

5/4&6/4mo

FR–

D:d

ryco

lor;M:m

oistco

lor;CB:cob

bly;V

GR:verygravelly;G

R:g

ravel;FG

R:fine

gravel;S:san

d;FS:finesand

;SL:sand

yloam

;LS:loam

ysand

.Deg

reeof

expression:

v1:verywea

k;1:

wea

k;Size:f:fine

;m:

med

ium;c:coa

rse;Structure:gr:g

ranu

lar;sbk:suban

gularblocky;m:m

assive;sg:

sing

legrain.

Freq

uenc

y:vf:veryfew;f:few

;c:com

mon

;m:m

any;Size:v1:

very

fine;1:

fine;2:

med

ium;3

:coa

rse;TU

:tub

ular

(worm

burrows).

Con

trast:F:faint;D:d

istin

ct;Typ

e:K:

calcium

carbon

ate;T:thread

s;fi:films;mo:

mottle

s.

FR:friab

le;FI:firm.

Distin

ctne

ss:A

:abrupt;C:clear;G

:gradua

l;To

pog

raphy

:S:smoo

th,W

:wavy.



Table

IVSo

ildescriptio

nforprofiles

1,2,

and3inTren

ch1(fron

tofthe

shelter).

Dep

thSo

ilMun

sell

Lower

(cm)

Unit

Horizon

Color

Texture

Structure

Roo

tsPores

Con

centratio

nsCon

sisten

cyBou

ndary

Other

Profile1

Profile2

D,M

0–40

0–40

VII

A10

YR4/2,

3/2

GRSL

1fgr

mv1

&1

cv1&1;

m,TU

–FR

AW

40–4

540

–48

VI

Bw

2.5Y

3/5,

4/3

FGRSiL

1fsbk

cv1&1

cv1&1;

m,TU

f1F10

YR5/6mo;

c

10YR

5/6oc

pf

FRAW

Laminated

inlower

5cm

,parts

alon

gbed

dingplane

s

55–7

348

–64

VC1

2.5Y

6/3,

5/3

SLm

cv1

m,TU

f1F2.5Y

6/6mo

FIAW

Com

mon

flecksof

very

fine

charco

al,culturaldep

osits

in

upper

5cm

73–9

864

–84

IVC2

2.5Y

R5/3,

4/3

FGRSiL

m–

cv1

f1P7.5Y

R3/3&

c1D2.5Y

6/6mo

FIAW

Fewco

bbles(Oga

llala)tap

ering

totheea

st

98–1

1084

–99

IIIC3

2.5Y

5/3,

4/3

CBSL

mfv1

cv1&1;

f,TU

f1F5Y

R4/4mo

FIAW

110–

190

99–1

66II

C4

7.5Y

R6/4,

5/4

FGRSL

mf1

f2&3

f1F5Y

R4/4mo

FRAW

190–

220

166–

186

IC5

2.5Y

5/3,

4/3

FGRSL

m–sg

fv1&1

c2&3

f1F2.5Y

R4/4mo

L–

Profile3

0–15

0IV

C1

2.5Y

R5/3,

4/3

FGRL-SiL

Stratifi

ed

150–

165

IVC2

2.5Y

R5/3,

4/3

CBSiL

165–

215

IVC3

2.5Y

R5/3,

4/3

SiL

Stratifi

ed

D:dry

color;M:m

oistco

lor;CB:cob

bly;G

R:g

ravel;FG

R:fine

gravel;SL:sand

yloam

;L:loa

m;SiL:siltloam

.

Deg

reeof

expression:

1:wea

k;Size:f:fine

,Struc

ture:g

r:gran

ular;sbk:suban

gularblocky;m:m

assive;sg:

sing

legrain.

Freq

uenc

y:f:few;c:com

mon

;m:m

any;Size:v1:

very

fine;1:

fine;2:

med

ium;3

:coa

rse;TU

:tub

ular

(worm

burrows).

Con

trast:F:faint;D:d

istin

ct;P

:prominen

t;Type:mo:

mottle

s;oc

:organ

icco

ats;pf:ped

faces.

FR:friab

le;FI:firm;L:loo

se.

Distin

ctne

ss:A

:abrupt;To

pog

raphy

:W:w

avy.



Figure 6 Sedimentary units, soil horizons, %C, δ13C values, and radiocarbon ages from profiles 1 and 2 in Trench 1 at the front of the shelter.

Figure 7 Sedimentary units, soil horizons, grain-size distribution, %C, δ13C, radiocarbon ages, and phytoliths from profile 3 in Trench 1 at the front of the

shelter.

Radiocarbon chronology

Seven radiocarbon ages determined on samples from thefront of the rockshelter are presented in Table II. Colla-gen from a bison bone 2 m below the surface in Unit IV

yielded an AMS 14C age of 2220 ± 30 yr B.P. Charcoal inUnit IV (east end of trench) yielded an AMS 14C age of1930 ± 30 yr B.P. Radiocarbon ages determined on thefive stratified charcoal samples range from 2205 ± 20 to2315 ± 20 14C yr B.P.



Figure 8 Phytolith assemblage recovered from profile 1 in Trench 1 at the front of the shelter. Note the Late Archaic horizon that contains an increase in

Celtis occidentalis leaf and fruit phytoliths.

Table V Lithic analysis from 281 specimens recovered from feature 2 in

Trench 1 (front of the shelter).

Mean Standard

Lithic Material Type Number Percent wt (g) Deviation

Fossilized Wood 114 40.6 .73 2.34

Niobrara Jasper 81 28.8 .81 2.27

Quartz (local) 29 10.3 .33 .43

Quartzite, unspecified 23 8.2 1.66 4.38

Opalized Ogallala Caliche 16 5.7 20.88 55.20

Hartville Chert 12 4.3 1.03 3.53

Unknown 6 2.1 1.78 3.53

Artifact Types

Cores/Tested Cobbles 2 0.7

Cortex (Presence) 11 3.9

Tools/Utilized Flakes 13 4.6

Debitage 266 94.6

Burned Specimens 14 4.6

Back of the Burntwood Creek Rockshelter

Lithology

Trenches 3A and 3B (Figures 1b, 3a) contain colluvial de-posits with many angular siliceous gravels and cobbles ofOgallala Group sedimentary rocks throughout both pro-files (Table VI). These deposits have been modified by soildevelopment. A modern surface soil (Soil 1) and three

buried soils with loamy sand to loam texture were ex-posed in Trench 3A (Figures 3c, 9). Soil 2 is a buried A–Cprofile from 54 to 93 cm below the land surface. Soil 3is represented by a Bwb2 horizon from 93 to 116 cm be-low the land surface. The A horizon of Soil 3 was com-pletely eroded, exposing the Bw horizon before burial.Soil 4 begins at 116 cm below surface and terminates on alarge block of roof-fall. Surface exposure, modern anthro-pogenic activity, and concomitant melanization accountsfor the high C content of Soils 3 and 4 (Figure 9).

Radiocarbon chronology

Even though no artifacts or cultural features were foundin either of Trenches 3A or 3B, flecks of charcoal frommodern hearths (Figure 3a) were abundant throughoutthe Trench 3A profile. Also, Soils 3 and 4 were very fri-able and showed evidence of bioturbation. SOM from theupper 10 cm of Soils 2, 3, and 4 yielded conventional 14Cages of 710 ± 70, 114.9 ± 0.5, and 102.4 ± 0.5 yr B.P.,respectively (Table I).

Stable isotopes

The δ13C values from Trench 3A are higher than the onesfrom Trench 1 by ∼3‰. There are three trends in Trench



Table

VISo

ildescriptio

nforTren

ch3A

(backof

theshelter).

Dep

thSo

ilMun

sell

Lower

(cm)

Horizon

Color

Texture

Structure

Roo

tsPores

Con

sisten

cyBou

ndary

Other

Tren

ch3A

Tren

ch3B

D,M

0–14

17–3

2A

10YR

5/2,

4/2

GRSL

1fgr

m1&v1

m,TU

FRCW

14–3

132

–54

Bw

2.5Y

6/3,

5/3

GRLS

1fsbk

–cv1&1;

m,TU

FRGS

Com

mon

krotov

ina6–

8cm

diameter

filledwith

Aho

rizonmaterial

31–5

454

–75+

C10

YR5/3,

4/3

GRSL

m–sg

–cv1&1;

c,TU

FRAS

54–7

5Ab1

10YR

5/2,

4/2

GRSL

1fgr

cv1&f2

cv1&1;

m,TU

FRGS

75–9

3ACb1

10YR

5/2,

4/2

GRL

v1fgr

cv1,

f2,f3

cv1&1;

c,TU

VFR

AW

93–1

16Bwb2

7.5Y

R4/3,

3/3

GRL

1m-cto

1fsbk

cv1&1

cv1&1

FRAS

Com

mon

hackberry

seed

s

116–

156

Ab3

7.5Y

R5/2,

4/2

FGRL

1fgr

fv1&1

cv1&1

FR–

D:d

ryco

lor;M:m

oistco

lor;GR:g

ravel;FG

R:fine

gravel;SL:sand

yloam

;L:loa

m;LS:loam

ysand

.

Deg

reeof

expression:

v1:verywea

k;1:

wea

k;Size:f:fine

,m:m

edium;c:coa

rse;Structure:gr:g

ranu

lar;sbk:suban

gularblocky;m:m

assive;sg:

sing

legrain.

Freq

uenc

y:f:few;c:com

mon

;m:m

any;Size:v1:

very

fine;1:

fine;2:

med

ium;3

:coa

rse;TU

:tub

ular

(worm

burrows).

VFR

:veryfriable;FR:friab

le.

Distin

ctne

ss:A

:Abrupt;C:clear;G

:gradua

l;To

pog

raphy

:S:smoo

th;W

:wavy.

3A from the bottom of the profile to the top (Figure 9).First, the δ13C values in Soils 3 and 4 average –18.5‰,and the C content is high. Second, there is an offset ofapproximately 4‰ toward more negative δ13C values atthe boundary between Soils 2 and 3. Through Soil 2, δ13Cvalues remain around –22‰, and C content decreases upthe profile. Finally, the δ13C values shift to an average of–18‰ in the modern surface soil (Soil 1).

Phytoliths

The phytolith assemblage from Trench 3A (Figure 9) cor-roborates the δ13C values. At the bottom of the profile, amixed C3 and C4 grass assemblage is represented in Soils3 and 4. Chloridoids increase and panicoids and pooidsdecrease in Soil 2. Beginning in Soil 3, spinulose sphere,polyhedral, and jigsaw-puzzle cells, indicating woody andother dicots, increase up the profile, and trichomes andbulliforms appear in Soil 2, indicating an increase in soilmoisture. Also, pooids are well represented throughoutthe sequence.

DISCUSSION

Site Formation

Although Burntwood Creek may have played a role inthe original carving of the Burntwood Creek Rockshelter,it is clear from the sedimentological record that differen-tial erosion by way of groundwater sapping affected theevolution of the shelter. Groundwater or spring sappingoccurs where groundwater outflow undermines slopes orweakens the basal support for cliffs (Baker, 1990). Thereare two lines of evidence that support this interpretation.First, the eastward-sloping geometry of well-sorted sandysediment (Unit I) suggests spring discharge from the backof the shelter transported the sands out of the friable,clastic Ogallala Formation, toward the front of the shel-ter (Figure 4). Sediment comprising Unit I dips 25◦ to theeast and was deposited on the floor of the shelter in sev-eral spring outflow events as indicated by grain-size data(Figure 5).

Second, CL images of the secondary carbonate massshow evidence for processes involving phreatic ground-water, derived from springs in the Ogallala Group. We in-terpret the orange color visible in thin sections under CLas an indication that Mn2+ was dissolved in such ground-waters (Figure 5a) (cf. Ten Have & Heijnen, 1985; Boggs& Krinsley, 2006). Furthermore, the calcite coatings (cf.Stoops, 2003) around silicate grains likely resulted fromthe dissolution of primary calcite crystals and the subse-quent reprecipitation of secondary calcite from discharg-ing groundwaters (Figure 5b). Domains of less-intense



Figure 9 Soil horizons, %C, δ13C, and the recovered phytolith assemblage from Trench 3A at the back of the shelter.

light-red color in the EF image (Figure 5c), however, in-dicate that an earlier precursor fabric was recrystallizedin situ within the mass (see McGarry & Baker, 2000).Therefore, petrographic observations indicate a minimumof two stages of development of secondary carbonate. Acomparative chemostratigraphic and petrographic studyof the Ogallala Group could reinforce our interpretation.

The sandy sediment comprising Unit I, all depositedby spring discharge, was mantled by colluvium extend-ing east from the paleodrip-line of the shelter (Units IIand III in Figure 4). Based on the ∼25◦ dip to the eastof Units II and III, the fine gravel to cobbly sandy loamtexture, and the brown to olive brown colors that matchthe shelter walls, we infer that the sediment was derivedfrom the weathered walls of the rockshelter below theroof-forming caprock.

The remainder of the depositional sequence at the frontof the shelter (Units IV–VII) is interpreted as either allu-vium or colluvium. At the distal (streamward) end of theshelter, a greater degree of sediment sorting and the pres-ence of horizontal bedding in silt loam deposits suggestthat Unit IV is mostly alluvium from Burntwood Creek.We infer from the multiple fining-upward sequences thatthe creek flooded frequently and thereby deposited allu-vium at the front of the shelter. Units V and VII are in-terpreted as colluvial deposits on the basis of geometry,

texture, and grain sorting (Table IV). The eastward slop-ing geometries and sandy loam to gravelly sandy loamtextures of the units suggest delivery of sediment fromthe roof and walls of the shelter over time. The poor sort-ing of Unit VI strongly suggest that it is colluvium, ratherthan alluvium; laminated silt loam sediment in the lower5 cm of Unit VI, however, probably indicates depositionby pour-off from the roof of the shelter during episodesof heavy rainfall (Figure 2a). Significant collapse of therockshelter roof likely took place prior to 2315 ± 20 14Cyr B.P. and Late Archaic occupation since the dated cul-tural deposits mantle a large block of roof-fall exposedin the north wall of Trench 1 (Figure 4). Thus, LateArchaic people constructed hearth features and workedstone tools in the open-air at the distal end of the shel-ter, activities consistent with ethnographic rockshelter re-search of Binford (1978), Gorecki (1991), and Walthall(1998).

It is difficult to determine when the back of the rock-shelter was exposed to open-air as it is today. The radio-carbon ages on SOM from the back of the shelter areproblematic because recent charcoal from historic andmodern campfires is present there. Soil mixing throughbioturbation clearly moved this recent charcoal down thesoil profile. An unconformity between Soils 3 and 4 mayindicate erosion by pour-off from the roof or by spring



flow. If the unconformity is a result of roof pour-off, thissuggests the roof collapsed sometime between 2400 and1000 yr. B.P., leaving the back of the shelter exposed tothe open-air. This relative chronology is likely given thetime-transgressive retreat of the rockshelter roof duringits relatively short lifespan (cf. Laville, Rigaud, & Sackett,1980; Goldberg & Mandel, 2008).

Archaeology

The Burntwood Creek Rockshelter was repeatedly occu-pied during the late Holocene. We associate the stratifiedcultural deposits with Late Archaic people on the basis ofseven 14C ages (1930 ± 30 yr B.P. to 2315 ± 20 14C yrB.P.), which fall solidly within the accepted age range forLate Archaic (Table I). Furthermore, ceramics are absentin the deposits. The unlined hearth features in associa-tion with faunal and chipped stone assemblages repre-sent small, multiple campsites. The lithic sample studiedfrom Features 1 and 2, consisting mostly of small piecesof debitage and shatter suggests the area just outside therockshelter overhang was used for resharpening or re-touching stone tools. The sample appears to be represen-tative of the material types and manufacture stage in thethree adjacent excavation units. Most of the lithic mate-rial (∼65%) would have been available from the local en-vironment. For example, the Ogallala Formation wouldhave yielded silicified wood, opalized caliche, quartz, andquartzite clasts. The high percentage of debitage and thelow percentage of primary cortical flakes, however, makeit unlikely that local materials were initially worked on-site. The small percentages of Niobrara Jasper (Kansassource ∼50 km away) and Hartville Chert (Hartville Up-lift, Wyoming, ∼400 km away) indicate some movementand/or trade throughout the region.

The presence of hackberry leaf and fruit phytoliths inthe front and back fills of the shelter indicates hackberrytrees were nearby, depositing leaves on the land surfaceas they do today. However, given the concentration ofhackberry phytoliths and seeds within Feature 1, hack-berry probably was used by the Late Archaic people forfuel or food as has been indicated from the archaeob-otanical record of several Late Archaic and Early Ceramicsites in the Central Plains (Adair, 2003; Scarry, 2003). Al-though hackberry fruits are relatively poor sources of pro-tein, fat, and carbohydrates (Scarry, 2003), they wouldhave been one of only a few sources of fleshy fruits, alongwith yucca. Furthermore, hackberry fruits are availableduring the fall and winter (Scarry, 2003), implying a fallor winter occupation of the shelter if the fruits were be-ing consumed when ripe rather than being burned at anygiven time.

Paleoenvironment

In both the front and back of the shelter, the δ13C valueson soil represent C3 or a mixed C3 and C4 plant com-munity, suggesting no major climate shifts in the lateHolocene. There is, however, a 3‰ offset between thefront and back of the shelter, indicating that the propor-tions of C3 and C4 plants were different. We attribute thelower δ13C values and phytolith composition at the frontof the shelter in Unit IV to Late Archaic hearth activities.

In general, the phytolith analysis yielded a diverse andwell-preserved assemblage of C3 and C4 grasses and C3

dicots such as hackberry (C. occidentalis) that were repre-sentative of the local environment. However, in Trench1 many broken phytoliths were recorded in Units I andII. Based on their degree of wear, and the greater propor-tion of C3 pooids, the dominant grass subfamily duringthe Miocene–Pliocene (Stromberg, 2002), to C4 chlori-doids, it is likely that those phytoliths were derived di-rectly from the Ogallala Formation during groundwatersapping and erosion of the shelter walls. It is not likelyother sediment sources contributed to Units I and II; thus,they are ancient phytoliths that were liberated from theOgallala Formation. Also, two samples from the Unit IValluvium in Profile 3 in Trench 1 have low phytolith con-centrations and are poorly preserved due to alluvial trans-port in Burntwood Creek. Redeposition of these phy-toliths makes paleoenvironmental interpretation difficult.Nonetheless, the phytoliths from the alluvium likely re-flect the plant community within the Burntwood Creekbasin.

The grasses of the C4 Chloridoideae were the mostabundant of the three subfamilies in both trenches, butthe abundance of chloridoids in both profiles is incon-sistent with δ13C values most likely due to modern andancient anthropogenic carbon input around activity ar-eas, or detrital carbon from multiple sediment sources.It is possible that chloridoids are a better indicator ofaridity than stable carbon isotopes, or that they producemore phytoliths than the other subfamilies—two hy-potheses that remain untested. Nevertheless, chloridoidswere growing on and around the rockshelter and theirphytoliths were transported into the rockshelter throughcolluvial and alluvial processes, but chloridoids at thesite also deposited the phytoliths. The C3 Pooideae docu-mented at depth (Units I and II) in Trench 1 and through-out the profile in Trench 3A is consistent with lower δ13Cvalues. The δ13C values from the surface soil and threeburied soils in Trench 3A indicate an increase in moisturebefore a gradual drying at the back of the shelter. TheC4 Panicoideae are not well represented at the rockshel-ter; their highest numbers are ∼15% of the phytoliths re-covered from Soils 1 and 4 in Trench 3A. Long-shanked



lobate panicoid phytoliths are easily broken during rede-position and can be mistaken for the saddle shapes ofchloridoid phytoliths in two-dimensional analysis (Sud-bury, 2011). However, during analysis, phytoliths wererotated to examine their three-dimensional shape.

CONCLUSIONS

The Burntwood Creek Rockshelter formed in the Ogal-lala Formation in part through the process of ground-water sapping and spring action. The roof subsequentlyretreated as it periodically collapsed over the last ∼2500years. As the rockshelter evolved, alluvium from Burnt-wood Creek, colluvium, and large blocks of roof-fall man-tled sandy spring deposits on its floor. These processesworked to both preserve and destroy the archaeologicalrecord at the rockshelter.

The riparian environment near the rockshelter in-cludes two sources of water: a spring emanating from theOgallala Formation and Burntwood Creek. Both sourceswould have been attractive to humans moving throughthe High Plains. We conclude from paleoenvironmentalanalyses that a mixed C3 and C4 plant community thrivedwithin and around the rockshelter and changed in com-position during the late Holocene. The differences in plantcommunity composition between the soil at the front andback of the shelter are likely a result of differences in wa-ter availability and exposure to sunlight as the rockshelterroof retreated. Differences in plant community composi-tion between the sedimentary units at the front of theshelter are likely a result of changes in sediment source.Also, the hearth activities of Late Archaic people affectedstable carbon isotope values and the composition of phy-tolith assemblages.

Excellent phytolith preservation (i.e., no dissolutionpits and few broken phytoliths) suggests that with theexception of Units I and II in Trench 1, and the alluviumfrom Burntwood Creek (Unit IV), redeposition was lim-ited. The phytoliths from units I and II likely representgrasses of Miocene–Pliocene age, and phytoliths from thealluvium represent snapshots of basin-wide grasses fromthe late Holocene. Also, C4 chloridoid phytoliths recov-ered in the laminated portion of Unit VI in Trench 1 mayhave come from the pour-off at the top of the shelter.

The Burntwood Creek Rockshelter provided a short-term camping locality for Late Archaic people. They leftbehind a mostly debitage (tertiary flakes) chipped stoneassemblage along with a small amount of deer and bi-son remains. Thus, the people who used the rocksheltermay have been responsible for the chipped stone surfaceassemblages at the other recorded sites in the valley. Acomparison of the chipped stone assemblages at each site

will aid in resolving the question of cultural affiliation. Atthis time, there is no evidence for Late Archaic activitiesat the bison jump at 14RW2 or the bone bed at 14RW3,although we do know that Late Archaic people were par-ticipating in large bison kills on the High Plains (Toddet al., 2001). Also, we do not have evidence that the rock-shelter was used while the Late Paleoindian bison jumpat 14RW2 was used. If a Late Paleoindian component didexist at the shelter, the sediments that would have con-tained those specific cultural deposits probably were re-moved by stream erosion during the middle Holocene, aprocess that occurred in most low-order streams acrossthe Central Plains (Mandel, 1995, 2006). Thus, there islow potential for finding deposits at the rockshelter thatpredate the late Holocene.

We graciously thank Dean and Theresa Knapp for allowing ac-cess to the Burntwood Creek Rockshelter. Jack Hofman (Uni-versity of Kansas) assisted us in the field and was involved withthe lithic analysis. Mark Volmut (University of Kansas) helpedus in the field and provided assistance with bone identifica-tion. Steve Bozarth (University of Kansas) assisted with phy-tolith identification. Greg Ludvigson (Kansas Geological Survey)aided in thin-section petrology. We thank Daphne Fautin (Uni-versity of Kansas), Jon Smith (Kansas Geological Survey), RobertM. Joeckel (University of Nebraska), and Paul Goldberg (BostonUniversity) for helpful suggestions in the early stages of themanuscript. Finally, we thank Joe Artz and two anonymous ref-erees for their valuable comments and suggestions. Our researchwas supported by the University of Kansas Odyssey Archaeolog-ical Research Fund and by a Carroll D. Clark Research Awardfrom the Department of Anthropology, University of Kansas.

REFERENCES

Abbott, J.T. (1997). Stratigraphy and geoarchaeology of the

Red Canyon rockshelter, Crook County, Wyoming.

Geoarchaeology: An International Journal, 12(4), 315–335.

Adair, M.J. (2003). Great plains paleoethnobotany. In P. E.

Minnis (Ed.), Plants and people in ancient eastern North

America (pp. 258–346). Washington: Smithsonian

Institution.

Baker, V.T. (1990). Spring sapping and valley network

development, with case studies by R. C. Kochel, V. R.

Baker, J. E. Laity, & A. D. Howard. In C.G. Higgins & D.R.

Coates (Eds.), Groundwater geomorphology: The role of

subsurface water in Earth-surface processes and landforms

(pp. 235–265). Boulder, Colorado: Geological Society of

America Special Paper 252.

Beeton, J.M., & Mandel, R.D. (2011). Soils and

late-Quaternary landscape evolution in the Cottonwood

River basin, East-Central Kansas: Implications for

archaeological research. Geoarchaeology: An International

Journal, 26(5), 693–723.

Bell, E.H., & Cape, R.E. (1936). The rock shelters of western

Nebraska in the vicinity of Dalton, Nebraska. In E.H. Bell



(Ed.), Chapters in Nebraska archaeology, Vol. 1 (pp.

357–399). Lincoln: University of Nebraska.

Binford, L.R. (1978). Nunamiut ethnoarchaeology. New York:

Academic Press.

Birkeland, P.W. (1999). Soils and geomorphology, 3rd ed.

New York: Oxford University Press.

Boggs, S., & Krinsley, D. (2006). Application of

cathodoluminescence imaging to the study of sedimentary

rocks. New York: Cambridge University Press.

Boutton, T.W. (1996). Stable carbon isotope ratios of soil

organic matter and their use as indicators of vegetation and

climate change. In T.W. Bouttton & S. Yamasaki (Eds.),

Mass spectrometry of soils. New York: Marcel Dekker, Inc.

Bowman, P.W. (1960). Coal-Oil Canyon (14LO1): Report on

preliminary investigations. Bulletin No. 1. Kansas

Anthropological Association, 1–70. Topeka, Kansas.

Brown, D. (1984). Prospects and limits of a phytolith key for

grasses in the central United States. Journal of

Archaeological Science, 11, 345–368.

Bruckschen, P., Neuser, R.D., & Richter, D.K. (1992). Cement

stratigraphy in Triassic and Jurassic limestones of the

Weserbergland (northwestern Germany). Sedimentary

Geology, 81(3–4), 195–214.

Buchanan, R. (1984). Kansas geology: An introduction to

landscapes, rocks, minerals, and fossils. Lawrence:

University Press of Kansas.

Collins, M. (1991). Rockshelters and the early archaeological

record in the Americas. In T.D. Dillehay & D. Meltzer

(Eds.), The first Americans: Search and research (pp.

157–182). Boca Raton: CRC Press.

Cyr, H., McNamee, C., Amundson, L., & Freeman, A. (2011).

Reconstructing landscape and vegetation through multiple

proxy indicators: A geoarchaeological examination of the

St. Louis Site, Saskatchewan, Canada. Geoarchaeology: An

International Journal, 26(2), 165–188.

Donahue, J., & Adovasio, J.M. (1990). Evolution of sandstone

rockshelters in eastern North America: A geoarchaeological

perspective. Geological Society of America, Centennial

Special, 4, 231–251.

Farrand, W.R. (2001a). Archaeological sediments in

rockshelters and caves. In J.K. Stein & W.R. Farrand (Eds.),

Sediments in context (pp. 29–66). Salt Lake City: The

University of Utah Press.

Farrand, W.R. (2001b). Sediments and stratigraphy in

rockshelters and cave: A personal perspective on principles

and pragmatics. Geoarchaeology: An International Journal,

16(5), 537–557.

Fenneman, N.M. (1931). Physiography of western United

States. New York: McGraw-Hill Book Company.

Fredlund, G.G., & Tieszen, L. (1994). Modern phytolith

assemblages from the North American Great Plains.

Journal of Biogeography, 21(3), 321–335.

Fredlund, G.G., & Tieszen, L.L. (1997). Phytolith and carbon

isotope evidence for late Quaternary vegetation and

climate change in the southern Black Hills, South Dakota.

Quaternary Research, 47, 206–217.

Frye, J.C., & Leonard, A.B. (1952). Pleistocene geology of

Kansas. Lawrence: University of Kansas.

Goebel, T., Graf, K.E., Hockett, B., & Rhode, D. (2003).

Late-Pleistocene humans at Bonneville Estates rockshelter,

eastern Nevada. Current Research in the Pleistocene, 20,

20–23.

Goldberg, P., & Mandel, R.D. (2008). Caves and rockshelters.

In D. M. Pearsall (Ed.), Encyclopedia of archaeology. New

York: Academic Press.

Gorecki, P. (1991). Horticulturalists as hunter-gatherers: Rock

shelter usage in Papua New Guinea. In C. Gamble & W.

Boismier (Eds.), Ethnoarchaeological approaches to mobile

campsites. Hunter-gatherer and pastoralist case studies.

Ann Arbor: Ethnoarchaeological Series 1, International

Monographs in Prehistory.

Habermann, D., Neuser, R.D., & Richter, D.K. (1998). Low

limit of Mn2+-activated cathodoluminescence of calcite:

State of the art. Sedimentary Geology, 116, 13–24.

Hassan, F.A. (1978). Sediments in archaeology: Methods and

implications for palaeoenvironmental and cultural analysis.

Journal of Field Archaeology, 5(2), 197–213.

High Plains Regional Climate Center. (2011). Period of record

monthly climate summary for McDonald, Kansas (145127).

http://www.hprcc.unl.edu/cgi-bin/cli perl lib/cliMAIN.

pl?ks5127.

Hoard, R.J., & Banks, W.E. (2006). Kansas archaeology.

Lawrence: University of Kansas Press.

Kansas State Historical Society. (2008). Kansas State Historical

Society Archeological Inventory. Topeka, KS: Kansas State

Historical Society.

Kelly, E.F., Blecker, S.W., Yonker, C.M., Olson, C.G., Wohl,

E.E., & Todd, L.C. (1998). Stable isotope composition of

soil organic matter and phytoliths as paleoenvironmental

indicators. Geoderma, 82, 59–81.

Kourampas, N., Simpson, I.A., Perera, N., Deraniyagala, S.U.,

& Wijeyapala, W.H. (2009). Rockshelter sedimentation in a

dynamic tropical landscape: Late Pleistocene-early

Holocene archaeological deposits in Kitulgala Beli-lena,

southwestern Sri Lanka. Geoarchaeology: An International

Journal, 24(6), 677–714.

Kuchler, A.W. (1974). A new vegetation map of Kansas.

Ecology, 55(3), 586–604.

Lauver, C.L., Kindscher, K., Faber-Langendoen, D., &

Schneider, R. (1999). A classification of the natural

vegetation of Kansas. The Southwestern Naturalist, 44(4),

421–443.

Laville, H., Rigaud, J.-P., & Sackett, J. (1980). Rockshelters of

the Perigord: Geological stratigraphy and archaeological

succession. New York: Academic Press.

Lintz, C., & Zabawa, L.G. (1984). The Kenton caves of

western Oklahoma. In R. E. Bell (Ed.), Prehistory of

Oklahoma (pp. 161–174). Orlando: Academic Press.



Ludvigson, G.A. (1989). Observations on the

cathodoluminescence petrography of the Coralville

Formation near Iowa city: Implications for regional

diagenetic patterns in the Devonian Cedar Valley group.

Iowa City: Geologic Society of Iowa Guidebook 51.

Ludvigson, G.A., Sawin, R.S., Franseen, E.K., Watney, W.L.,

West, R.R., & Smith, J.J. (2009). A review of the

stratigraphy of the Ogallala Formation and revision of

Neogene (“Tertiary”) nomenclature in Kansas. Current

Research in Earth Sciences, Bulletin 256, part 2.

http://www.kgs.ku.edu/Current/2009/Ludvigson/

index.html, 1–9.

Mandel, R.D. (1992). Soils and Holocene landscape evolution

in central and southwestern Kansas: Implications for

archaeological research. In V.T. Holliday (Ed.), Soils in

archaeology (pp. 41–100). Washington, D.C.: Smithsonian

Institution Press.

Mandel, R.D. (1995). Geomorphic controls of the archaic

record in the Central Plains of the United States. In E. A.

Bettis, III (Ed.), Archaeological geology of the archaic

period in North America (pp. 37–66). Boulder, Colorado:

Geological Society of America Special Paper 297.

Mandel, R.D. (2006). Late Quaternary and modern

environments in Kansas. In R. J. Hoard & W. E. Banks

(Eds.), Kansas archaeology (pp. 10–27). Lawrence:

University of Kansas Press.

Mandel, R.D. (2008). Buried Paleoindian-age landscapes in

stream valleys of the central plains, USA. Geomorphology,

101, 342–361.

Mandel, R.D. (2012). Late Quaternary landscape evolution in

western Kansas: Implications for archaeological research.

Lawrence, KS: Kansas Geological Survey Bulletin.

Mandel, R.D., & Simmons, A.H. (1997). Geoarchaeology of

the Akrotiri Aetokremnos rockshelter, southern Cyprus.

Geoarchaeology: An International Journal, 12(6), 567–605.

Mandel, R.D., Holen, S., & Hofman, J.L. (2005).

Geoarchaeology of Clovis and potential pre-Clovis cultural

deposits at the Kanorado locality, northwestern Kansas.

Current Research in the Pleistocene, 22, 56–57.

Martin, J.E., Alex, R.A., Alex, L.M., Abbott, J.P., Benton,

R.C., & Miller, L.F. (1993). The Beaver Creek Shelter

(39CU799): A Holocene succession in the Black Hills of

South Dakota. Plains Anthropologist, 38(145), 17–36.

McGarry, S., & Baker, A. (2000). Organic acid fluorescence:

Applications to speleothem paleoenvironmental

reconstruction. Quaternary Science Reviews, 19,

1087–1101.

Merriam, D.F. (1963). The geologic history of Kansas.

Lawrence, Kansas: Kansas Geological Survey Bulletin 162.

Meyers, W.J. (1974). Carbonate cement stratigraphy of the

Lake Valley formation (Mississippian) Sacramento

Mountains, New Mexico. Journal of Sedimentary

Petrology, 44, 837–861.

Murphy, L.R., & Mandel, R.D. (2007). Geoarchaeology of the

Burntwood Creek Rockshelter (14RW418), northwest

Kansas. Paper presented at the Annual Geological Society

of America Conference. Denver.

Over, W.H. (1936). The archaeology of Ludlow Cave and its

significance. American Antiquity, 2(2), 126–129.

Palmer, L., Mandel, R.D., Kruse, J.M., & Gillen, T. (2010).

Archaeological site testing for national register nomination:

25GD66, 25GD67, 25MO32, 25MO37/122, and 25MO82,

Morrill and Garden counties, Nebraska. Lawrence, Kansas:

Archeology Laboratory, Augustana College, Sioux Falls,

South Dakota and the Kansas Geological Survey,

University of Kansas.

Piperno, D. (2006). Phytoliths: A comprehensive guide for

archaeologists and paleoecologists. Lanham, MD: AltaMira

Press.

Rainey, D.K., & Jones, B. (2007). Rapid cold water formation

and recrystallization of relict bryophyte tufa at the Fall

Creek Cold Springs, Alberta Canada. Canadian Journal of

Earth Sciences, 44, 889–909.

Reeves, C.C., Jr. (1976). Quaternary stratigraphy and geologic

history of the southern High Plains. In W. C. Mahaney

(Ed.), Quaternary stratigraphy of North America.

Stroudsburg, Pennsylvania: Dowden, Hutchinson, and

Ross.

Russell, J.P., & Hofman, J.L. (2006). Research at the

Burntwood Creek site, Kansas. Proceedings of the 64th

Annual Plains Anthropological Conference. Topeka,

Kansas.

Scarry, C.M. (2003). Patterns of wild plant utilization in the

prehistoric eastern Woodlands. In P. E. Minnis (Ed.),

People and plants in ancient eastern North America (pp.

50–104). Washington: Smithsonian Institution.

Soil Survey Division Staff. 1993. Soil survey manual. United

States Department of Agriculture, Handbook No. 18. U.S.

Government Printing Office, Washington, DC. 437 pp.

Stein, M. (2005). The 2005 Kansas archeology training

program: Archeological survey in Rawlins, Sherman,

Thomas, and Wallace counties, Kansas (No. B3601).

Topeka: Kansas State Historical Society.

Stromberg, C.A.E. (2002). The origin and spread of

grass-dominated ecosystems in the late Tertiary of North

America: Preliminary results concerning the evolution of

hypsodonty. Palaeogeography, Palaeoclimatology,

Palaeoecology, 177, 59–75.

Stoops, G. (2003). Guidelines for analysis and description of

soil and regolith thin sections. Madison, Wisconsin: Soil

Science Society of America, Inc.

Sudbury, J.B. (2011). Quantitative phytolith analysis–A

working example from modern prairie soils and buried

Holocene A horizons. Phytolith Press Research Monograph

1. Ponca City, Oklahoma: Phytolith Press.

Tate, M. (1999). Archaic stage. In K. P. Gilmore, M. Tate, M.

L. Chenault, B. Clark, T. McBride, & M. Wood (Eds.),

Colorado prehistory: A context for the Platte River Basin

(pp. 91–174). Denver: Colorado Council of Professional

Archaeologists.



Ten Have, T., & Heijnen, W. (1985). Cathodoluminescence

activation and zonation in carbonate rocks: An

experimental approach. Geologie en Mijnbouw, 64,

297–310.

Todd, L.C., Jones, D.C., Walker, R.S., Burnett, P.C., &

Eighmy, J. (2001). Late Archaic bison hunters in northern

Colorado: 1997–1999 excavations at the Kaplan-Hoover

bison bonebed (5LR3953). Plains Anthropologist, 46(176),

125–147.

Twiss, P.C., Suess, E., & Smith, R.M. (1969). Morphological

classification of grass phytoliths. Proceedings of the Soil

Science Society of America, 33, 109–115.

USDA NRCS. (2004). Soil survey laboratory methods manual

(pp. 735): Soil survey investigations report No. 42, Version

4.0. National Resources Conservation Service. Lincoln,

Nebraska.

USDA NRCS. (2010). The PLANTS Database. Baton Rouge,

LA: National Plant Data Center. http://plants.usda.gov.

Walthall, J.A. (1998). Rockshelters and hunter-gatherer

adaptation to the Pleistocene/Holocene transition.

American Antiquity, 62(2), 223–

238.

Wedel, W.R. (1986). Central Plains prehistory: Holocene

environments and culture change in the Republican River

Basin. Lincoln: University of Nebraska Press.

Weston, T. (Ed.). (1982). Archeological investigations at Cold

Brook and Cottonwood Springs reservoirs, Fall River

County, South Dakota. Project Report Series No. 50.

Omaha, Nebraska: U.S. Army Corps of Engineers.

Wood, J.J. (1967). Archaeological Investigations in

northeastern Colorado. Unpublished Ph.D. Dissertation,

Boulder, Colorado: University of Colorado.

Wood, W.R., & McMillan, R.B. (1976). Prehistoric Man and

his environments: A case study in the Ozark Highland.

New York: Academic Press.

Woodward, J.C., & Bailey, G.N. (2000). Sediment sources and

terminal Pleistocene geomorphological processes recorded

in rockshelter sequences in north-west Greece. In I. D. L.

Foster (Ed.), Tracers in geomorphology (pp. 521–551).

New York: John Wiley & Sons Ltd.

Woodward, J.C., & Goldberg, P. (2001). The sedimentary

records in Mediterranean rockshelters and caves: Archives

of environmental change. Geoarchaeology: An

International Journal, 16(4), 327–354.


Geoarchaeology and Paleoenvironmental Context of the Burntwood Creek Rockshelter, High Plains of...

Documents

Transcript of Geoarchaeology and Paleoenvironmental Context of the Burntwood Creek Rockshelter, High Plains of...