Climatic geomorphology: a critique - CiteSeerX

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Climatic geomorphology: a critiqueC.R. Twidale and Y. Lageat Department of Geology and Geophysics, University of Adelaide, Adelaide,AustraliaUniversité Blaise Pascal and URA 1562 of the CNRS, Clermont-Ferrand,France

Abstract: Though climatic geomorphology has long been perceived as providing a realisticframework for landform analysis, only the arid, nival and glacial systems and some constructionalforms on the coast are readily identified in the landscape, present and past, as climatically zonal incharacter. Of course these features together account for a substantial part of the Earth’s land surfaceat present. Nevertheless, the remaining areas have been subdivided into morphogenetic regions saidto be characterized by distinctive landform assemblages. Even in those regions shaped by distinctiveclimatically driven processes, however, structural forms and those of etch origin are significantcomponents, as they are also in humid tropical and midlatitude lands. In addition, variouslandforms are shaped by processes and mechanisms which, though climatically generated, varygenetically, and are active in a wide range of conventionally delineated climatic regions. Theytransgress arbitrary climatic boundaries. The climatic factor in landform development is by nomeans as clear cut and simple as was once thought and is certainly not of over-riding importanceover at least half the world’s land surface.

I Introduction

During this century, geomorphology has been dominated by the thesis that landformdevelopment is largely controlled by climate. Structural factors have been widely acknowl-edged and then forgotten, possibly because they were perceived as being self-evident. Theevolutionary, cyclic concepts of Davis (1899) and especially King (1942; 1953) have been,and are, important components of geomorphological analysis, but to realize the pervasiveinfluence of the climatic thesis one has only to examine the organization of mostgeomorphological texts, with their chapters on ’the landscape in aridity’, the effects

wrought by glaciers, periglacial landforms, contrasts between arid and humid lands, thenormal cycle and the like, and to note the discussion of inselbergs, pediments and alluvialfans, for example, in the context of particular (in these instances, arid, semi-arid) climaticconditions.

It was Davis himself who formally suggested arid and glacial landscape cycles additionalto the normal or humid temperate (Davis, 1905; 1906), but the climatic concept was

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rapidly adopted and developed by European geographers, and notably by de Martonne(1913), Passarge (1926), Thorbecke (1927) and Sapper (1935). The concept finds its firstformal expression in English rather later, with Peltier’s (1950) well-known exemplificationof the periglacial cycle as a morphogenetic region and his all-embracing exposition andjustification of the climatic concept. By then, however, the notion was already implicit inthe organization of many earlier texts in English and was indeed the basis of books likeCotton’s splendid Climatic accidents (1948). In addition, the thesis of climatic control findsovert acknowledgement, justification and expression in the series collectively known as theTrait6 de Giomorphologie (Tricart and Cailleux, 1962-69), in collections like that of

Derbyshire (1973), and in texts like those of Thomas (1974) and Faniran and Jeje ( 1983).Bfdel’s several papers and book (1977; see also Kiewiet de Jonge, 1984) provide not onlya superb exposition of the morphogenetic theme but also add another dimension with theconcept of climatomorphogenetic regions, or regions dominated by various (supposedly)climatically related landform assemblages: glaciated, with frost action; glaciated but withvalley incision; extratropical regions dominated by valleys; subtropical pediment domi-nated landscapes; and tropical planation surfaces (Büdel, 1961; 1963). Climatically basedinterpretations have been applied to terrains dominated by particular rock types, such aslimestone (Lehmann et al., 1954) and granite (Wilhelmy, 1958), and to coastlines (Davies,1964). An earlier review of climatic geomorphology is provided by Stoddart (1969).The assumptions underlying the thesis of climatic control are simple and persuasive.

Various climatic factors, and particularly temperature, precipitation and wind, induce theoperation of specific processes together known as the morphogenetic or geomorphicsystem. They produce landforms and landform assemblages that are typical of and peculiarto the particular climatic regime. Such climatically based landform assemblages are knownas morphogenetic regions. The concept had and has special appeal for geographers, for themorphogenetic system was perceived as having the potential to become a unifying themelinking climate, land surface, soil, vegetation and hence in some measure fauna and landuse. In terms of morphogenetic systems a map of climatic regions in effect, and to a greateror lesser degree, becomes, a map of geographical regions.

Desert, glacial and possibly also the periglacial or nival, morphogenetic regions arereadily recognized in the landscape. Together they occupy about 50% of the land areas. Allare distinctive by virtue of landform assemblages that are essentially related to existingclimatic regimes, are of recent origin and which are unique either in type or scale. Suchcoastal features as coral reefs, fiords and the strandflat have a zonal distribution. In thebroader, continental context, considerable dunefields are developed in coastal and nivalregions (e.g., Seppala, 1972) but only in the midlatitude deserts are there really extensivefields of dunes. Moreover, only here are barchans and linear, or longitudinal forms,developed. Relic desert, nival and glacial forms occupy large areas of the present humidand temperate lands (e.g., Grove, 1958; Andr6, 1991) and such features as pingos alsooccur beyond the present nival range (e.g., Pissart, 1963). But such inherited forms serveonly to reinforce the morphogenetic concept for they demonstrate climatic control in pasteras.

What, however, of the remaining 50% of the land areas not embraced and shaped bymodern glacial, nival or desert systems? They too are widely held to be subdivided intomorphogenetic regions (selvas, savannas, temperate lands, boreal and maritime regions,according to author) which reflect various and varied geomorphic systems induced byclimatic conditions, and which allegedly display distinctive landform assemblages. Thefollowing comments apply particularly to these humid regions, though they are also



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relevant to the regions affected by ’climatic accidents’.First, however, several vulgar adverse criticisms have been levelled at the concept of

morphogenetic regions. They are readily dismissed. For instance, difficulties with grada-tional and temporally varying zones rather than sharp and constant boundaries merelyreflect natural conditions. Peltier’s suggestion that running water is not important inshaping desert landscapes simply reflected a limited knowledge of deserts and of the desertliterature (e.g., Peel, 1941). Such commentaries and the ease with which they are refutedor resolved ought not, however, to be allowed to disguise the very real problems posed bylandscapes in terms of climatic control and morphogenetic regions. They can beconsidered under three headings: structural impacts; the etch factor; and mechanisms andprocesses which, though climatically induced, are in detail generated in response todifferent climatic conditions and transgress climatic boundaries. Structural impacts arewell known, and the unifying effects of fluvial activity and other surface and near-surfacewaters are alluded to by some, though not by most, while the implications of etching haveonly recently been explored (Twidale, 1990a; 1990b) . Yet examples of each are developedin most of our conventionally defined climatic regions.

11 Structural impacts

Structural impacts are both active and passive, major and minor, obvious and subtle, andthe distribution and characteristics of a wide range of structural landforms are the result offactors totally unrelated to present or past climates (see Yatsu, 1966; Sparks, 1971;Gerrard, 1988). For example, the distribution of volcanoes is related either to the locationand type of plate boundary or to mantle plumes and associated hotspots. The developmentof ancient volcanic provinces can be linked to the trajectories of the host land masses overhotspots (see, e.g., Duncan, 1991). Moreover, the morphology and eruptive character-istics of volcanoes varies with lava composition (which in turn varies with type of platejunction). The timing of volcanic activity varies with regional stress patterns.

Similarly, the character of orogenic belts and the fold mountains developed on themvaries with palaeogeography and tectonics, according to sediment source and conditions ofdeposition in the ancestral basins or troughs, pre-existing structure and relief in thedepositional basins, and stress conditions during orogenesis. Thus the major ridges of thecentral and southern Flinders Ranges, in the arid/semi-arid interior of South Australia, areunderlain by sandstone, the character and variations in thickness of which are relatedpartly to the predominantly granitic character of the source area to the west (the AustralianShield), partly to the easterly flow of rivers on to the then continental shelf and slope,resulting in thick quartzitic formations and hence in massive ridges and ranges on thewestern side of the upland. Crustal stress has also caused the development of faults withthe result that fault-generated forms, whether tectonic or structural, are the same the worldover so that the Great Rift Valley of central Africa is structurally and morphologicallysimilar to, albeit at a different scale from, the Lake George Rift of Upper New York State,those developed in the American west, and in the upper Rhine valley in western Europe.At a more local scale, fracture patterns related to crustal stress constitute perhaps the

most significant single structural control of landform development (e.g., Birot, 1952;Rognon, 1967). Hence, for example, the widespread and climatically azonal formation ofbomhardts in rock types that vary in composition and texture but which are consistentlymassive with well developed orthogonal fracture sets (e.g., Godard, 1977; Twidale, 1982;



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1987; Lageat, 1989). In some instances the patterns of fracture are demonstrably of someantiquity. Thus in the Gawler Ranges, in the interior of South Australia, the orthogonalsystems which form the basis of the bornhardts of the dacitic massif are of Late Proterozoic

age (Campbell and Twidale, 1991). Similarly, lineaments of regional extent and of LateProterozoic age have determined the shape of the fragments - the present continents - thatresulted from the break-up of the ancient Laurasia and Gondwana supercontinents. Thusnot only the present outline of Australia but also the orientation of many major features(river courses, outlines of uplands and basin plains) within the continent reflect thepresence of lineaments which in turn are related to stresses developed during earlier cyclesof plate disintegration, migration and welding (see, e.g., Meinesz, 1947; Hills, 1946; 1955;1956; 1961; Nance et al., 1988).Fractures form avenues along which meteoric waters and groundwaters infiltrate and

circulate, altering the rocks with which they come into contact. They give rise to corestonesand boulders, and to many bornhardts or convex upward (domical) residuals in granite,gneiss, limestone, sandstone and conglomerate. In each case, the plan size and shape arepartly determined by fracture pattern (time being the other major factor). Where fracturepatterns vary, so do the landforms developed on them. Thus penitent rocks (Bussersteine -see Ackermann, 1962) are characteristic of schist and gneiss terrains (see, e.g., Turner,1952) and stand in stark contrast with the rounded residuals typical of granite exposures.Fracture-controlled clefts or Kluftkarren are the result of the preferential weathering anderosion of fracture zones. They are developed at various scales, in various bedrocks and invarious climatic conditions. On the other hand, fractures allow meteoric waters to

percolate through the rock mass. For massifs located above the water table, a welldeveloped system of open partings may have a preservative or protective function (Twidaleand Campbell, 1993).Composition is an obvious factor determining the distribution of weathering and erosion

(e.g., Petit, 1971), but it also has subtle effects. Thus some inselbergs of French Guyanahave been attributed to their being underlain by leucogranite lacking biotite and hencemore resistant that the rock in which the surrounding plains are eroded (Hurault, 1963).Lamego (1938) attributed the vertical western face of the Pao de Assugar, bordering theBahia Guanabara, to its being coincident with the interface between a bed of biotite gneissand the lenticular gneiss which forms the mass of the residual. Dumanowski (1968)pointed out that though the granites of the Karkonosze Mountains of southern Poland varyin composition, all are lacking in biotite and are for that reason resistant (see also Birot,1950; Isherwood and Street, 1976). Lagasquie (1984) has pointed to petrologicaldifferentiation in granitoids in the Pyrenees, and to their morphological expressions.Several workers have drawn attention to compositional and textural contrasts betweeninselbergs and adjacent plains in Africa - Thorp (1969) and Selby (1977), for example,pointing to the presence of granitic uplands and schist plains in the Air Mountains of thesouthern Sahara and Namibia, respectively.

Stress, either residual or applied has been invoked in explanation of a suite of minorforms, developed mainly in granite (e.g., Jennings and Twidale, 1971; Peterson, 1975;Twidale and Sved, 1978), but also reported from other lithological settings. A-tents aredeveloped in cold lands like Labrador as well as hot arid and semi-arid regions of Australia.Such features continue to develop (Coates, 1964; Bowling and Woodward, 1979;Twidale, 1986), those in natural situations possibly triggered by minor seismic events.

Earth tremors also play a significant role in the initiation of landslides and other forms ofmass movement. Thus, not only did the earthquake that hit the San Fernando Valley of



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southern California in February 1971 cause more than 1000 landslides in a single squarekilometre (Morton, 1971) but also the landslides formed in the Bewani and Torricellimountains of northern New Guinea in 1935 were almost certainly triggered by earthtremors (Simonett, 1967). The notable feature of this last observation is that abundance oflandforms associated with mass movements was cited by Peltier (1950) as the mostcharacteristic feature of the selvas or humid tropical morphogenetic region; perhaps suchregions with well developed deep regoliths provide optimal conditions for landslidedevelopment, enhanced by the possibility of seismic initiation.

Drainage patterns are in large measure controlled by structure (e.g., Zemitz, 1931 ), andeven anomalous patterns have been explained in structural and tectonic terms, invokingsuch mechanisms as superimposition and antecedence. In addition, deep erosion and theexposure of structures that vary in their geometry vertically, such as has taken place in theFlinders and Appalachian ranges, are encapsulated in the concept of valley impression andstream persistence (see Meyerhoff and Olmstead, 1936; Oberlander, 1965; Twidale,1972).

All of the instances cited are totally independent of climatic influences, past or present.Moreover, until recently certain landforms which were regarded as climatic or zonal arenow seen as of structural origin. Thus inselbergs, especially those developed in graniticrocks and of domical form, were - and still are by some - treated as of arid/semi-aridprovenance; and this despite the domical forms having been described from the coastalrain forests of Brazil more than 150 years ago (Darwin, 1846). Similarly, towers inlimestone (towerkarst, Turmkarst) have been widely regarded as humid tropical forms withparticularly noteworthy developments in the Antilles, monsoonal northern Australia andsoutheast Asia. Now, however, they are increasingly seen as basically structural formswhich owe their origin to the exploitation of strong vertical fractures. Brook and Ford(1976; 1978) have described towers and associated labyrinth karst from the Canadiannorthwest developed in postglacial times in a climate or climates at least as cold as thatwhich obtains at present. Thus was the climatic provenance of towerkarst brought intoquestion, and the significance of earlier reported towers from southern Poland andSwitzerland (e.g., Gilewska, 1964) re-examined. Meantime, Verstappen (1960) haddrawn attention to the fact that in Indonesia cupolas or domes of limestone stand on slightrises, in comparatively dry sites, whereas towers occur on nearby alluvial plains. Thereason is that, as several workers have pointed out, weathering by moisture retained inalluvium or other unconsolidated veneers lapping against the bases of the residuals hascaused undermining, collapse and steepening of sidewalls, and the conversion of cupolasto towers (e.g., Lehmann, 1954; Verstappen, 1960; Jennings and Sweeting, 1963; Wilfordand Wall, 1965; Monroe, 1966; 1969; Miotke, 1973; Jennings, 1976; Twidale, 1987).

III The etch factor

Groundwaters are ubiquitous. They extend to depths of as much as ten kilometres, butcommonly to a depth of one kilometre, beneath the continents, and thus complete thehydrospheric envelope. Water reacts with all the common rock-forming minerals, most ofwhich are soluble to a greater or lesser degree, and many of which are subject to hydrationor hydrolysis. Slaking is a physical breakdown as a result of water weakening theelectrostatic bonding of minerals. Groundwaters charged with chemicals are, additionally,reactive. Moreover, groundwaters are the medium in which many biota, especially



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bacteria, circulate, causing further alteration and disintegration. Such reactions betweenwater and bedrock cause the development of a mantle of altered bedrock called theregolith. The upper zone of the regolith, where organic inputs are pronounced, is the soil.The base of the regolith, the junction between the regolith and the still intrinsically freshbedrock, is the weathering front (Mabbutt, 1961 a) .Groundwaters exploit every weakness in the bedrock. Fractures are penetrated,

susceptible minerals and strata more rapidly weathered. Thus the shape of the weatheringfront comes to reflect the character of the country rock and to develop a varied

morphology. The regolith is friable and lacking in cohesion. It is readily evacuated oreroded to expose the weathering front. Even where, as has commonly happened both atpresent and in the past, duricrusts have developed as a result of weathering, the induratedhorizon is frequently underlain by altered (commonly kaolinized) materials that are

susceptible to erosion. Thus it is not uncommon for the erstwhile weathering front to beexposed, and the landforms, major and minor, that originated at the weathering front, butare now exposed, are known as etch forms.Groundwaters and hence regoliths underlie all or most of the continents. For this reason

etch forms - of similar morphology because they reflect the exploitation of structuralweaknesses by shallow groundwaters - are found not only over a wide range of climates butalso in various lithological contexts. The rate of development may vary for climatic or forlithological reasons. For example, the rate of development is, almost certainly, more rapidin the humid tropics because of higher ambient temperatures, higher rainfall and abundantorganic acids than in, say, cold lands; but the range of forms developed is similar

everywhere, given similar structural settings. Perhaps too much should not be made ofthis, however, for most of the etch forms under discussion derive from earlier periods whenclimates were different from those that prevail at present; many, though by no means all,developed when torrid atmospheric climates prevailed over wide areas, and when thereforeregolithic climates would have been especially conducive to the rapid alteration of mosttypes of bedrock.The morphology of etch forms varies in detail according to structure. For example,

whereas smooth concave flared slopes have evolved in massive granite, sandstone, rhyolite,etc., the form is represented by rather rough notches in less massive materials. But thevirtual ubiquity of groundwaters implies that etch forms of various types are widespread.They are azonal both in the climatic and in the lithological senses.The ’etch’ (or ’etched’) concept can be traced back to 1791 when Hassenfratz published

a description of granitic boulders he had observed near Aumont (and probably nearChazeirolettes - see Twidale, 1978; 1990a) in the southern Massif Central, some fullyexposed, others partly exposed from beneath the mantle of disintegrated granite in whichthey were - and still are - embedded. Hassenfratz astutely realized that he had observedstages in the exposure of rounded boulders that had originated beneath the land surface.He noted that ‘... on apercoit tous les interm6diaires entre un bloc de granit dur contenuet enchass6 dans la masse totale du granit friable et un bloc enti6rement d6gag6’(Hassenfratz, 1791: 101).

Hassenfratz’s deductions embrace important principles. First, the granite boulders hadevolved in two stages, the first involving differential subsurface weathering, the second thepreferential stripping of the disintegrated bedrock, leaving the still cohesive masses of

intrinsically fresh rock as boulders. Many etch forms have two ages (Godard, 1966), andthis conclusion stands despite the recognition of etch forms that have evolved in four ormore stages (Twidale and Vidal Romani, 1994). Secondly, once in relief the boulders



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tended to persist because they were dry sites and because they shed water. Thus theimportance of water, of wet and dry sites, was highlighted (Barton, 1916), as werereinforcement or positive feedback mechanisms.

Subsequently, MacCulloch (1814) demonstrated the significance of fractures as loci forthe penetration of meteoric waters and hence the course of weathering. Logan (1849;1851) correctly deduced that vertical flutings he observed on the steep sides of graniteblocks on Palo Ubin, at the eastern end of the Strait of Johore, were likewise of subsurfaceorigin, for he noted that they extended beneath the soil cover which was of weatheredgranite in situ.

Falconer (1911) was responsible for a major advance when he suggested that someinselbergs, too, are of etch origin. Like the other early workers mentioned, he did not usethe term but the mechanism is clearly described: ’A plane surface of granite and gneisssubjected to long-continued weathering at base level would be decomposed to unequaldepths, mainly according to the composition and texture of the various rocks. Whenelevation and erosion ensued, the weathered crust would be removed, and an irregularsurface would be produced from which the more resistant rocks would project’ (Falconer,1911: 246).Falconer clearly envisaged that some masses of resistant rocks - though he did not

specify the nature of the resistance - projected into the base of the regolith, later to becomeresidual hills. A few years later, Jutson (1914) suggested that some of the extensive plainseroded in granite, gneiss and greenstone in the southwest of Western Australia wereformed by the stripping of a (lateritic) regolith (see also Brock and Twidale, 1984). Theseworkers clearly envisaged that certain landforms they had observed, mainly in tropicalregions, had formed in two stages and were of etch origin, though they did not use thatterminology. That came with Wayland (1934) and Willis (1936).The significance of the etch mechanism may be measured first by the extent of the

resultant forms and, secondly, by the number of otherwise puzzling features it is capable ofexplaining (see, e.g., Twidale, 1990b). Recent years have seen a confirmation andextension of the etch concept, with workers in many parts of the world identifying a widerange of such landforms. Thus extensive plains of etch origin have been demonstrated inseveral parts of the world, and notably in the southwest of Western Australia (Jutson,1914; Mabbutt, 1961b), southern Africa (e.g., Partridge and Maud, 1987; Twidale, 1988)and west Africa (Thomas and Thorp, 1983). The extraordinarily flat Nullarbor Plain -that the trans-Australia railway runs in a perfectly straight line for almost 500 km is ameasure of its lack of relief - is eroded in Miocene limestone. About 65 m of section is

missing in the southern part of the region (Lowry, 1970), and it has been suggested thatthe surface is the result of etch planation beneath a (moist) soil cover (Twidale, 1990b).Nascent bornhardts or domical inselbergs have been identified in artificial exposures in

western and southern Africa (Boye and Fritsch, 1973; Twidale, 1982), as have flaredslopes in granite in southern Australia, southern France and central Spain (Twidale, 1962;1982; Centeno, 1989). Boulders of etch type are recognized from basalt and sandstone,limestone and granite, as well as norite and other plutonic basic or intermediate rocks(e.g., Hutton et al., 1977). Rock basins, gutters, grooves, flares and pitting have also beensuggested as being initiated beneath the regolith at the weathering front in variouslithological and climatic settings.

Etch forms are present even in glaciated lands; indeed some workers consider that manyerosional features preserved in glaciated regions are basically of etch origin. Boye (1950)many years ago suggested that glaciers act as bulldozers and merely evacuate the pre-



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existing regolith, so that many bedrock forms characteristic of glaciated lands are

essentially exposed preglacial weathering fronts. This point has been developed with thesuggestion that many glaciated uplands in particular reflect glacial exploitation of pre-existing landscapes formed by fracture-controlled weathering and river erosion (Twidale,1990b).The differential subsurface weathering that eventually gives rise to minor etch forms

appears to be faint or subdued. Thus when cleared of their thin cover of regolith, some ofthe Kwaterski Rocks, on northwestern Eyre Peninsula, were already dimpled through thedevelopment of numerous shallow saucer-shaped depressions that are the precursors ofrock basins of various types. Recent stripping of a thin regolith from some of the graniteplatforms at the Cassia City of Rocks, Idaho, has revealed linear depressions or gutters thatare very faint but which, it is predicted, will develop into gutters or Rillen. Reinforcementor positive feedback effects lead to the exploitation of any initial contrast in relief.Moreover, differentiation takes place after exposure so that saucer-shaped depressions, forexample, become either hemispherical pits, flat-floored pans, cylindrical hollows orarmchair-shaped depressions according to the structure and slope of the sites on whichthey occur. Rock doughnuts and rock levees are formed in relation to basins and gutters asa result of differential weathering of wet (covered) and dry (exposed) zones (Twidale,1988).Karst workers long ago reached similar conclusions concerning limestone features,

rounded forms being referred to as covered or originating beneath a soil or regolithic cover,angular features as uncovered or developed on fully exposed rock surfaces, and some beinghalf covered or part epigene and part subsurface in origin (e.g., Eckert, 1902; Lindner,1930; Zwittkovits, 1966; Palmer, 1984).Rock towers well illustrate the problems of climatic interpretation for they not only

evolve in a wide range of climatic environments but also in bedrocks additional tolimestone. For example, they are reported in conglomerate in the Pyrenees (Barrere,1968), the Olgas complex of central Australia (Twidale and Bourne, 1978) and the well-known Meteora residuals of central Greece and in the Pajakunkah region of Sumatra(Verstappen, 1960). In sandstone, they occur for instance on the Roraima Plateau ofVenezuela (Demangeot, 1985; Schubert and Huber, 1990), in central Germany (e.g., theExtemsteine Horn, near Bad Meinberg), in the English Pennines (e.g., Linton, 1964), inthe so-called Lost City of Arnhemland, in northern Australia (Jennings, 1979), in HunanProvince of south-central China (Yuan Dioxian, personal communication, 10 August1992) and in the Vila Velha region of southeastern Brazil. Miniature towers in rhyolitic tuffare recorded from New Mexico (Mueller and Twidale, 1988) and in granitic rocks,represented by castle koppies in Zimbabwe, and by the ’tors’ of many cold lands, such asBohemia (e.g., Demek, 1964), Dartmoor (e.g., Linton, 1955), Newfoundland (e.g.,Schrepfer, 1933) and the Pyrenees (e.g., Twidale, 1982).Some towers appear to have evolved through the exploitation of strong, widely spaced

vertical fractures (see, e.g., Barr~re, 1968; Brook and Ford, 1976; 1978). In other areasthere are clear indications that this exploitation has taken place beneath the land surface.In particular, flared sidewalls are developed in many areas. Moreover, basal weathering,undermining and collapse of bounding slopes sufficient to convert domes to towers, iswidely in evidence. In karst terrains, slots and caves are commonplace and, associated asthey are with residuals on which convex crests manifestly give way downslope to steepenedcliffs due to undermining and collapse, the nature of the mechanism responsible forconverting domes to towers is obvious. In other lithological environments, such as



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sandstone, flared slopes or notches argue similar scarp-foot weathering and steepening ofbounding slopes but obviously unstable facets are not commonplace in such a massive andcohesive rock as granite. Additionally, the situation is frequently complicated by thepresence of sheet structure (granite), foliation (gneiss) and bedding and jointing (sand-stone and conglomerate); nevertheless, the same mechanism appears feasible and it

operates over a range of climatic conditions and in several lithological environments.Most of the early recognized etch forms and effects derive from the tropics. The

piedmont angle, the abrupt transition from hill to plain, is particularly prominent in aridand semi-arid midlatitude lands, standing in marked contrast to the gradual merging ofplain and upland typical of temperate regions (see, e.g., Hills, 1955). The piedmont anglehas been attributed to scarp-foot weathering (Twidale, 1967), but the mechanism is notrestricted to arid lands - witness the distribution of flared slopes in a wide range of climaticcontexts - though it is particularly effective there. Where suitable structural conditionsobtain, with caprocks in regions of flat lying sedimentary sequences or marked lithologicalcontrasts in folded sedimentary terrains, abrupt transitions between hill and plain are welldeveloped. The chalk scarplands of southern England and northern France provideexcellent examples. But uplands rising sharply from plains or valley floors are the norm inarid and semi-arid lands. Paradoxically perhaps, water being scarce, it is the more

important as an agent of alteration in aridity than in humid climates.All this is not to suggest that there are no morphological variations within the humid

lands that are reasonably to be attributed to climatic variations. For example, nubbinsappear to be confined to the humid tropics or to areas that have experienced suchconditions during the period of their formation. Thus nubbins are found, on the one hand,in northern Australia and Hong Kong and, on the other, in the southwestern USA(Oberlander, 1972). This distribution may reflect the effectiveness of moist regoliths inbreaking down sheet structure for those of the southwestern USA evidently developed inwarm humid conditions during the Tertiary (Oberlander, 1972). Also, though widelydistributed, some forms may be more prevalent in some areas than others: thus coveredpediments occur outside the tropics but are undoubtedly best and most widely developedin the arid and semi-arid regions. Again, flared slopes, though reported from a wide rangeof climatic and lithological environments, are undoubtedly best and most commonlydeveloped in granite in southern Australia, a distribution, however, that reflects theessential and comparative stability of the region as much as any particular climate.

IV Climatically generated processes and mechanisms common to several climaticregions

Many processes and mechanisms are active over a wide range of climatic regions. Theirprecise character and genesis may differ from region to region but the end results are thesame. Moreover, many enduring landforms are the result of storm or catastrophic events,events which find no expression in the climatic averages that are the basis of climaticclassification, yet which leave an enduring imprint on the landscape.

Rivers are a major force shaping the landscape in all but the glacial regions, and eventhere they occasionally erode channels either in, within or, more significantly from thepoint of view of eventual bedrock morphology, beneath the glacier ice. Most of the majorerosional forms of deserts are shaped by rivers generated by the occasional rains that are afeature of every desert (e.g., Peel, 1941).



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There is reason to believe that the quantitative data concerning channel shape andgeometry derived by Leopold and his colleagues (e.g., Leopold et al., 1964) do not hold indetail for, say, monsoonal rivers, but the assemblage of forms associated with fluvialerosion and deposition is found in most climatic regions. There is a range of forms ratherthan a single set, but that spectrum is found over a wide range of climatically basedregions. Channels and flood plains, terraces and deltas, meandering and braided patterns -none is restricted to a single climatically defined region. Some are the result of a commonmechanism, others are formed in varied circumstances.

Braided river channels are a good example. The braided pattern reflects three factors.First, low water: all rivers would appear braided if the flow were reduced such that theshoal and pool bedforms were exposed. Secondly, they reflect an inefficient but effectiveresponse to high discharge conditions, to floods. But the reason for high discharge may beepisodic rains (as in deserts), seasonal rains (as in monsoon lands) or spring melt (as inperiglacial lands). Thirdly, they reflect steeper gradients, which may be due to structure ortectonics (e.g., Twidale, 1966). However, the influence of gradient may be compensatedor cancelled by channel characteristics, as for instance where steep mountain streamsemerge on to piedmont plains, leave the confines of gorges and divide into a number ofchannels; total cross-section is increased and stream efficiency decreased; and the coarseload is deposited, causing further hydraulic inefficiency and further deposition andsubdivison of channels.

Similarly, both alluvial fans and covered pediments or glacis, though widely regarded asdesert and semi-desert forms, are in fact widely distributed. Alluvial fans are well

developed in such regions as the Canadian Rockies as well as desert lands, for example.Rock pediments are etch forms and are correspondingly widely distributed. Coveredpediments are found in Colorado, Utah and Alaska, in Korea and Japan, as well as aridand semi-arid regions. The reason is that the fluvial conditions necessary for their

development transgress the boundaries of conventionally defined climatic regions. Pedi-ments, for example, reflect flood conditions active in a piedmont zone, and such highvariations in stream discharge can be induced not only by the episodic rains of deserts butalso by monsoon rains, and by spring snow melt (Twidale, 1981). Such pediments are notrestricted to low, midlatitude semi-arid lands, as required by Budel’s climatomorphoge-netic system, though they are well developed in such regions. Like scarp-foot weathering,many fluvial mechanisms transgress climatic boundaries and are convergent in the sensethat they are generated in various ways but with similar end products.

Certain other landforms are developed in contrasted climatic settings though they arethe result of similar mechanisms. Thus gilgai, or patterned ground caused by the churningof soils rich in hydrophilic clays, are found in regions with rainfall as low as 250 mm (e.g.,in the Coober Pedy area of the interior of South Australia) and as high as 1100 mm (on theDarling Downs of southeastern Queensland): all that is required is wet and dry periods,whether seasonally or episodically distributed, and a suitable thickness of hydrophilic clay(e.g., Springer, 1958; Hallsworth, 1968; Hubble et al., 1983).

Lunettes, much favoured by some as (semi-arid) climatic indicators (e.g., Bowler,1973), are known from a considerable range of climatic regions. In Australia, for example,they are reported from monsoonal north Queensland and humid temperate Tasmania, aswell as from the Mediterranean and savannah lands of southern Australia. Large, activelydeveloping lunettes as well as the dissected remnants of older forms occur on the northernmargin of Lake Eyre in a hyperarid region (e.g., Dulhunty, 1983) and indeed at themargins or many other desert playas where they play a crucial role in dune initiation



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(Wopfner and Twidale, 1988). Lunettes develop spasmodically, with constructionalphases during dry periods or seasons, interspersed with standstill or dissection during wetperiods.

Tafoni are found in massive rocks, typically granite but also sandstone, in arid and semi-arid lands, and also in seasonally dry coastal areas, but in a wide range of precipitationaverages and in cold as well as hot regions - in Antarctica as well as central Australia; thecommon feature is conditions suitable for salt crystallization (e.g., Klaer, 1956; Calkin andCailleux, 1962; Martini, 1978; Bradley et al., 1978).

Similar forms have been produced by different processes. For example, castle koppiesappear to have evolved where just the crests of domical masses have been exposed asplatforms, and the covered areas have been weathered in the zone just beneath the landsurface (Twidale, 1982). Such castellated forms are found in cold lands where theweathering may be due to freeze-thaw in the near surface zone, and in relation to oldplanation surfaces in southern Africa. Here the subsurface weathering may have beeneffected by soil and regolithic moisture over a lengthy period. The exposure of the buriedflanks of granitic masses steepened by subsurface weathering (probably frost action in highlatitudes and altitudes, chemical reactions between water and bedrock in low latitudes) isachieved in part at least by solifluxion in cold climates, but by streams in tropical lands.Natural caves and arches are the result of wave action on coasts, river action in valleys, butmost commonly by subsurface moisture attack (Twidale and Centeno, 1993). Somebornhardts are the result of upfaulting, others to the differential weathering and erosion ofcontrasted rock types, but most are two-stage etch forms that were initiated beneath theland surface at the weathering front (Twidale, 1982). Different processes acting onbedrock possibly of contrasted origins (plutonic, sedimentary, metamorphic) but withsimilar physical properties (and particularly similar fracture patterns) produce similarlandforms: convergence or equifinality is commonplace in geomorphology.

Finally, catstrophic events which leave their imprint on the landscape occur independ-ently of climate. Some catastrophically induced landforms are extraterrestrial in origin, formeteorite impacts (or low-level asteroid explosions) either of recent age or of some

antiquity are found the world over (see, e.g., Gostin et al., 1986; Williams, 1986; Miltonand Sutter, 1987). Others are tectonic, such as the earthquake-related features and thevolcanic eruptions referred to earlier. Tsunamis generated by submarine eruptions andearthquakes have been cited to account for otherwise puzzling coastal forms (e.g., Youngand Bryant, 1992).Extreme climatic events that are not accounted for in the climatic means that are the

bases of climatic classifications also have an enduring impact on the landscape. The mostdramatic, but possibly unique, example is provided by the channelled scablands located inthe northwestern USA (see, e.g., Bretz et al., 1956). The remarkable channels and otherfluvial forms eroded in a basaltic high plain are due to brief but enormous floods followingthe breaking of a glacier dam that impounded Lake Missoula during the Late Pleistocene(Baker, 1973). But flood plain deposits may not all be related to gradual, progressivefluvial accretion, for in some areas they appear to consist not of single sequences as a resultof either vertical accretion or lateral corrasion and related deposition of point bars butrather to periods of accumulation separated by floods and related erosion that leave onlyremnants of earlier deposits among the later (e.g., Nanson, 1986). Disequilibriumconditions because of storm or high-energy events are far more commonly manifested inthe landscape than has been supposed. Human impacts, and especially the clearance ofvegetation by various means and for various reasons, fall into this category, for they



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produce disequilibrium (e.g., Tricart and Cailleux, 1972) and epicycles of erosion anddeposition. Gullying, for example, is similar whether it be located in southern Africa,western Europe or the southwestern USA. Its perceived significance may vary greatly fromregion to region, but causations are basically similar. However, though gullying and otherforms of soil erosion are both widespread and obvious, both appear to be restricted inspace and time. Thus Vogt ( 1953) has noted a seventeenth-century phase of soil erosion inwestern Europe that was overcome by improved farm husbandry, and observations inmany parts of the world suggest, for instance, that gullying develops rapidly in uncon-solidated rocks but makes little impression on lithified but weak materials such as shale. Inthe geological context, though not the human, even catastrophic soil erosion is ephemeraland unimportant.

V Conclusion

Climatic impacts are not denied but they have been overestimated. Desert assemblages,glaciated lands and nivally shaped land surfaces are readily recognizable. The distributionof some specific landforms, such as nubbins, appears to be zonal, and features such astafoni that are the result of salt crystallization are developed in arid and semi-arid terrestrialand coastal areas. In addition, rivers have produced a range of forms that is not confined toany one climatic region. The proposed humid tropical or selvas morphogenetic regioncharacterized by abundant mass movements is difficult to define, for landslides andearthflows may be triggered by seismic events and river action produces a similar range offorms the world over. Etch forms are widely represented in the landscape, and they too aresimilar though they may have evolved at different rates in contrasted climatic zones.Structural effects are ubiquitous not only finding direct expression in the landscape butalso in influencing the type and rate of weathering and erosion.The major contrast between various climatic regions is not so much in the type or

assemblage of forms developed but rather in the rate at which they evolve, though this factormay well be subdued by the realities of climatic change and the warm, humid climatesprevalent over wide areas through much of the Cainozoic, and by the fact that many forms areof considerable antiquity.

Climatic factors are important in inducing the operation of processes that find clearexpression in landform assemblages the world over, but together they constitute but one ofseveral factors that determine the shape of the Earth’s surface at regional and local scales.Climate is certainly not an over-riding consideration in the interpretation of landscape.Sweeting’s statement concerning karst is applicable to landscapes as a whole: ‘... we know thatthough climatic differences effect karst processes, the correlations between climate andlandform are not as simple as we once supposed’ (Sweeting, 1976: 1).



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References

Ackermann, E. 1962: Biissersteine - Zeugen Vorzeit-licher Grundwasserschwankungen. Zeitschrift fürGeomorphologie 6, 148-82.

André, M.-F. 1991: L’empreinte glaciaire dans lesVosges. Presses Universitaires de Nancy, 119 p.

Baker, V.R. 1973: Paleohydrology and sedimentologyof Lake Missoula flooding in eastern Washington.Geological Society of America Special Paper, 144, 79 p.

Barrère, P. 1968: Le relief des Pyrénées centrales

occidentales. Journal d’Etudes Pau-Biarritz 194,31-52.

Barton, D.C. 1916: Notes on the disintegration ofgranite in Egypt. Journal of Geology 24, 382-93.

Birot, P. 1950: Notes sur le problème de la désagréga-tion des roches cristallines. Revue de GéomorphologiesDynamique 1, 271-76.

— 1952: Le relief granitique dans le nord-ouest de laPéninsule Ibérique. Proceedings, 17th International

Geographical Union (Washington, DC), 301-303.Bowler, J.M. 1973: Clay dunes: their occurrence,

formation and environmental significance. Earth Sci-ence Reviews 9, 315-38.

Bowling, A.J. and Woodward, R.C. 1979: An inves-tigation of near surface rock stresses at CopetonDamsite in New South Wales. Australian Geom-

echanics Journal G9, 5-13.Boyé, M. 1950: Glaciaire et périglaciaire de l’Ata Sund,

Nord-oriental Groenland. Paris: Herrmann.

Boyé, M. and Fritsch, P. 1973. Dégagement artificield’un dôme cristallin au Sud Cameroun. Travaux et

Documents de Géographie Tropicale 8, 69-94.Bradley, W.C., Hutton, J.T. and Twidale, C.R.

1978: Role of salts in development of granitic tafoni,South Australia. Journal of Geology 86, 647-54.

Bretz, J.H., Smith, H.T.U. and Neff, G. 1956:

Channeled scablands of Washington: new data andinterpretations. Geological Society of America Bulletin67,957-1049.

Brock, E. J. and Twidale, C.R. 1984: J.T. Jutson’scontributions to geomorphology. Australian Journalof Earth Sciences 31, 107-21.

Brook, G.A. and Ford, D.C. 1976; The NahanniNorth karst: a question mark on the validity of themorphoclimatic concept of karst development. Pro-ceedings of the 6th International Congress on Speleology2,43-57.

— 1978: The origin of labyrinth and tower karst andthe climatic conditions necessary for their develop-ment. Nature 275, 493-96.

Büdel, J. 1961: Morphogenese der Festlandes imAbhangigkeit von den Klimazonen. Die Naturwis-senschaften 48, 313-18.

— 1963: Klimagenetische Geomorphologie. Geogra-phische Rundschau 7, 269-86.

— 1977: Klima Geomorphologie. Stuttgart:Borntraeger.

Calkin, P. and Cailleux, A. 1962: A quantitativestudy of cavernous weathering (tafonis) and its appli-cation to glacial chronology in Victoria Valley, Ant-arctica. Zeitschrift für Geomorphologie 6, 317-24.

Campbell, E.M. and Twidale, C.R. 1991: The evo-lution of bornhardts in silicic volcanic rocks, Gawler

Ranges, South Australia. Australian Journal of EarthSciences 38, 79-93.

Centeno, J.D. 1989: Evolution cuatenaria del relieveen la Vertiente sur del Sistema Central Español. Lasformas residuales como indicadoras morfologicas.Cuadernos de Laboratoris Xeoloxico de Laxe 13,79-88.

Coates, D.R. 1964: Some cases of residual stress

effects in engineering works. In Judd, W.R., editor,The state of stress in the Earth’s crust. Amsterdam:

Elsevier, 679-88.Cotton, C.A. 1948: Climatic accidents. Christchurch:Whitcombe & Tombs.

Darwin, C.R. 1846: Geological observations on SouthAmerica. London: Smith, Elder.

Davies, J.L. 1964: A morphogenetic approach to

world shorelines. Zeitschrift für Geomorphologie 8,127-44.

Davis, W.M. 1899: The geographical cycle. Geo-

graphical Journal 14, 481-504.— 1905: The geographical cycle in an arid climate.

Journal of Geology 13, 381-407.— 1906: The sculpture of mountains by glaciers.

Scottish Geographical Magazine 22, 273-322.Demangeot, J. 1985: Montagnes et cascades de

Haute-Guyane vénézuelienne. Bulletin de l’Associa-

tion de Géographes Français 4, 243-54.Demek, J. 1964: Castle koppies and tors in the Bohe-

mian Highland (Czechoslovakia). Biuletin Peryglac-jalny 14, 195-216.

Derbyshire, E., editor, 1973: Climatic geomorphology.London: Macmillan.

Dulhunty, J.A. 1983: Lunettes of Lake Eyre North,South Australia. Transactions of the Royal Society ofSouth Australia 107, 219-22.

Dumanowski, B. 1968: Influence of petrological dif-ferentiation of granitoids on landforms. GeographicaPolonica 7, 93-98.

Duncan, R.A. 1991: Ocean drilling and the volcanicrecord of hotspots. Geology Society of America Today11,213-15.

Eckert, M. 1902: Das Gottesackerplateau. ZeitschriftDeutscher Osterreichen Alpenvereinsheft 31, 52-60.

Falconer, J.D. 1911: Geology and geography of northern



332

Nigeria. London: Macmillan.Faniran, A. and Jeje, L.K. 1983: Humid tropical

geomorphology. London: Longman.

Gerrard, A.J. 1988: Rocks and landforms. London:Unwin Hyman.

Gilewska, S. 1964: Fossil karst in Poland. Erdkunde18, 124-35.

Godard, A. 1966: Les ’tors’ et le problème de leurorigine. Revue Géographique de l’Est 6, 153-70.

— 1977: Pays et paysages du granite. Introduction à une

géographie des domaines granitiques. Paris: PUF.Gostin, V.A., Haines, P.W., Jenkins, R.J.F., Com-

pston, W. and Williams, I.S. 1986: Impact ejectahorizon within late Precambrian shales, AdelaideGeosyncline, South Australia. Science 233, 198-200.

Grove, A.T. 1958: The ancient erg of Hausaland.

Geographical Journal 124, 528-33.

Hallsworth, E.G. 1968: The gilgai phenomenon. In Ahandbook of Australian soils. Glenside, South Aus-tralia : Rellim, 415-20.

Hassenfratz, J.-H. 1791: Sur l’arrangement de plu-sieurs gros blocs de différentes pierres que l’onobserve dans les montagnes. Annales de Chimie 11,95-107.

Hills, E.S. 1946: Some aspects of the tectonics ofAustralia. Journal and Proceedings of the Royal Societyof New South Wales 79, 67-91.

— 1955: Die Landoberfläche Australiens. Die Erde 7,195-205.

— 1956: A contribution to the morphotectonics ofAustralia. Journal of the Geological Society of Australia3, 1-15.

— 1961: Morphotectonics and the geomorphologicalsciences with special reference to Australia. QuarterlyJournal of the Geological Society of London 117,77-89.

Hubble, G.D., Isbell, R.F. and Northcote, K.R.1983: Features of Austalian soils. In Soils, an Aus-tralian viewpoint. London: Commonwealth Scientificand Industrial Research Organization, MelbourneAcademic Press, 17-47.

Hurault, J. 1963: Recherches sur les inselbergs grani-tiques nus en Guyane Française. Revue de Géomor-

phologie Dynamique 14, 49-61.Hutton, J.T., Lindsay D.S. and Twidale, C.R.

1977: The weathering of norite at Black Hill, SouthAustralia. Journal of the Geological Society of Australia24, 37-50.

Isherwood, D. and Street, A. 1976: Biotite-inducedgrussification of the Boulder Creek Granodiorite,Boulder County, Colorado. Geological Society ofAmerica Bulletin 87, 366-70.

Jennings, J.N. 1976: A test of the importance of cliff-foot caves in tower karst development. Zeitschrift fürGeomorphologie Supplement-Band 26, 92-97.

— 1979: Arnhemland city that never was. Geo-

graphical Magazine 60, 822-27.Jennings, J.N. and Sweeting, M.M. 1963: The lime-

stone ranges of the Fitzroy Basin, Western Australia.Bonner Geographische Abhandlung, 32.

Jennings, J.N. and Twidale, C.R. 1971: Origin andimplications of the A-tent, a minor granite landform.Australian Geographical Studies 9, 41-53.

Jutson, J.T. 1914: An outline of the physiographicalgeology (physiography) of Western Australia. Geo-logical Suruey of Western Australia Bulletin, 61, 240 p.

Kiewiet de Jonge, C.J. 1984: Büdel’s geomorphology.Progress in Physical Geography 8, 218-48 and 8,365-97.

King, L.C. 1942: South African scenery. Edinburgh:Oliver & Boyd.

— 1953: Canons of landscape evolution. GeologicalSociety of America Bulletin 64, 721-52.

Klaer, W. 1956: Verwitterungsformen in Granit aufKorsika. Petermanns Geographisches MitteilungenErgänzungsheft, 261, 1-146.

Lagasquie, J.J. 1984: Géomorphologie des granites - lesmassifs granitiques de la moitié orientale des Pyrénéesfrançaises. Paris: Editions du CNRS.

Lageat, Y. 1989: Le relief du Bushveld. Une géomorpholo-gie des roches basiques et ultrabasiques. Clermont-Ferrand : Association des Publications, Faculté desLettres et Sciences Humaines de l’Université Blaise

Pascal, nouvelle série, fascicule 30.Lamego, A.R. 1938: Escarpas do Rio de Janeiro.

Ministero da Agriculte Departamento Nacional da Pro-ducao Mineral Servico Geologico e Mineralogico Boletim,93, 72 p.

Lehmann, H. 1954: Der tropische Kegelkarst auf denGrossen Antillen. Erdkunde 8, 130-39.

Lehmann, H., Roglic, J., Rathjens, C., Lasserre,G., Harrassowitz, H., Corbel, J. and Birot, P.1954: Das Karstphänomen in den verschiedenenKlimazonen. Erdkunde 8, 112-22.

Leopold, L.B., Wolman, M.G. and Miller, J.P.1964: Fluvial processes in geomorphology. San

Francisco, CA: Freeman.Lindner, H. 1930: Das Karrenphänomen. Petermanns

Mitteilungen Ergänzungsheft 208, 83 (also Gotha:Perthes).

Linton, D.L. 1955: The problem of tors. GeographicalJournal 121, 470-87.

— 1964: The origin of the Pennine tors - an essay inanalysis. Zeitschrift für Geomorphologie 8, 5-24.

Logan, J.R. 1849: The rocks of Palo Ubin. Verhan-dlung Genootschap van Kunsten en Wetenschappen(Batavia) 22, 3-43.

— 1851: Notices of the geology of the Straits of

Singapore. Quarterly Journal of the Geological Societyof London 7, 310-44.

Lowry, D.C. 1970: The geology of the Western Aus-



333

tralian part of the Eucla Basin. Geological Survey ofWestern Australia Bulletin, 122, 201 p.

Mabbutt, J.A. 1961 a: ’Basal surface’ or ’weatheringfront’. Proceedings of the Geologists’ Association (Lon-don) 72, 357-58.

— 1961b: A stripped land surface in Western Aus-tralia. Transactions and Papers of the Institute of BritishGeographers 29, 101-14.

MacCulloch, J. 1814: On the granite tors of Cornwall.Transactions of the Geological Society 2, 66-78.

Martini, I.P. 1978: Tafoni weathering with examplesfrom Tuscany. Zeitschrift für Geomorphologie 22,44-67.

Martonne, E. de 1913: Le climat, facteur de relief.Scientie, 339-55.

Meinesz, F.A.V. 1947: Shear patterns of the Earth’scrust. Transactions of the American Geophysical Union28, 1-61.

Meyerhoff, H.A. and Olmstead, E.W. 1936: Theorigins of Appalachian drainage. American Journal ofScience 36, 21-42.

Milton, D.J. and Sutter, J.P. 1987: Revised age forthe Gosses Bluff impact structure, Northern Terri-tory, Australia, based on 40Ar/39Ar dating. Mete-oritics 22, 281-89.

Miotke, F.-D. 1973: The subsidence of the surfacebetween mogotes in Puerto Rico east of Arecibo

(trans. W.H. Monroe). Caves and Karst 15, 1-12.Monroe, W.H. 1966: Formation of tropical karst

topography by limestone solution and reprecipita-tion. Caribbean Journal of Science 6, 1-7.

Morton, D.M. 1971: Seismically triggered landslidesin the area above the San Fernando Valley. In TheSan Fernando, California, earthquake of February 9,1971. United States Geological Survey ProfessionalPaper 733, 99-104.

Mueller, J.E. and Twidale, C.R. 1988: Geomorphicdevelopment of City of Rocks, Grant County, NewMexico. New Mexico Geology 10, 74-79.

Nance, R.D., Worsley, T.R. and Moody, J.B. 1988:The supercontinent cycle. Scientific American 259,44-51.

Nanson, G.C. 1986: Episodes of vertical accretion andcatastrophic stripping. A model of disequilibriumfloodplain development. Geological Society of AmericaBulletin 97, 1467-75.

Oberlander, T.M. 1965: The Zagros Streams. Syr-acuse Geographical Series, 1, 168 p.

— 1972: Morphogenesis of granitic boulder slopes inthe Mojave Desert, California. Journal of Geology 80,1-20.

Palmer, A.N. 1984: Geomorphic interpretation ofkarst features. In LaFleur, R.G., editor, Groundwateras a geomorphic agent. London: Allen & Unwin,173-209.

Partridge, T.C. and Maud, R.R. 1987: Geomorpho-logical evolution of southern Africa since the Meso-zoic. Transactions of the Geological Society of SouthAfrica 90, 179-208.

Passarge, S. 1926: Morphologie der Klimazonen oderMorphologie der Landsehaftgütel. Petermanns Geo-graphische Mitteilungen 72, 173-75.

Peel, R.F. 1941: Denudation landforms of the centralLibyan Desert. Journal of Geomorphology 4, 3-23.

Peltier, L.C. 1950: The geographic cycle in periglacialregions as it is related to climatic geomorphology.Annals of the Association of American Geographers 40,214-36.

Peterson, J.A. 1975: An A-tent from plateau Labra-dor. Australian Geographical Studies 13, 195-99.

Petit, M. 1971: Contribution à l’étude morphologique desreliefs granitiques à Madagascar. Tananarive: Imprim-erie Centrale.

Pissart, A. 1963: Les traces de ’pingos" du Pays deGalles (Grande Bretagne) et du Plateau des HautesFagnes (Belgique). Zeitschrift für Geomorphologie 7,147-65.

Rognon, P. 1967: Le Massif de l’Akator et ses bordures(Sahara central). Etude géomorphologique. Paris: Cen-tre National de la Recherches Scientifique.

Sapper, K. 1935: Geomorphologie der Feuchten Tropen.Leipzig: Teubner.

Schrepfer, H. 1933: Inselberge in Lappland undNeufundland. Geologische Rundschau 24, 137-43.

Schubert, C. and Huber, J. 1990: The Gran Sabana.Panorama of a region. Caracas: Lagover.

Selby, M.J. 1977: Bornhardts of the Namib Desert.Zeitschrift für Geomorphologie 21, 1-13.

Seppala, M. 1972: Location, morphology and orienta-tion of inland dunes in northern Sweden. GeografiskaAnnaler 54A (2), 85-104.

Simonett, D.S. 1967: Landslide distribution and

earthquakes in the Bewani and Torricelli Mountains,New Guinea. In Jennings, J.N. and Mabbutt, J.A.,editors, Landform studies from Australia and NewGuinea. Canberra: Australian National UniversityPress, 64-84.

Sparks, B.W. 1971: Rocks and relief. London:

Longman.Springer, M.E. 1958: Desert pavement and vesicular

layer of some soils of the Lahontan Basin, Nevada.Proceedings of the Soil Science Society of America 22,63-66.

Stoddart, D.R. 1969: Climatic geomorphology:review and re-assessment. Prog. Phys. Geog 1,159-222.

Sweeting, M.M. 1976: Present problems in karst

geomorphology. Zeitschrift für GeomorphologieSupplement-Band 26, 1-15.



334

Thomas, M.F. 1974: Tropical geomorphology. London:Macmillan.

Thomas, M.F. and Thorp, M.B. 1983: Environmen-tal change and episodic etch planation in the humidtropics of Sierra Leone: the Koidu etch plain. InDouglas, I. and Spencer, T., editors, Environmentalchange and tropical geomorphology. London: Allen &

Unwin, 239-67.Thorbecke, F. 1927: Der Formenschatzun periodisch

trochnen Tropenklima mit Uberwiegender Trock-enzeit. Düsseldorfer Geographischger Vorträge und Erör-tung 3, 10-17.

Thorp, M.B. 1969: Some aspects of the geomorphol-ogy of the Air Mountains, southern Sahara. Transac-tions, Institute of British Geographers, 47, 25-46.

Tricart, J. and Cailleux, A. 1962-69: Traité de Géom-

orphologie. Introduction à la géomorphologie climatique(1965); Le modelé des régions périglaciaires (1967); Lemodelé de régions glaciaires et nivales (1962); Le modelédes régions sèches (1969); Le modelé des régions chaudes,forêts et savanes (1965). Paris: Société d’Editions

d’Enseignement Supérieur.— 1972: An introduction to climatic geomoyphology

(trans. C.J. Kiewiet de Jonge). London: Longman.Turner, F.J. 1952: Gefiigerelief illustrated by ’schist

tor’ topography in central Otago, New Zealand.American Journal of Science 250, 802-807.

Twidale, C.R. 1962: Steepened margins of inselbergsfrom north-western Eyre Peninsula, South Australia.Zeitschrift für Geomorphologie 6, 51-69.

— 1966: Late Cainozoic activity on the SelwynUpwarp. Journal of the Geological Society of Australia13,491-94.

— 1967: Origin of the piedmont angle, as evidencedin South Austalia. Journal of Geology 75, 393-411.

— 1972: The neglected third dimension. Zeitschriftfür Geomorphologie 16, 283-300.

— 1978: Early explanations of granite boulders.Revue de Geomorphologic Dynamique 27, 133-42.

— 1981: Origins and environments of pediments.Journal of the Geological Society of Australia 28,423-34.

— 1982: Granite landforms. Amsterdam: Elsevier.— 1986: A recently formed A-tent on Mt Wudinna,

Eyre Peninsula, South Australia. Revue de Gémorpho-logie Dynamique 35, 21-24.

— 1987: A comparison of inselbergs developed onvarious massive rocks. Ilmu Alam 16, 23-49.

— 1988: Granite landscapes. In Moon, B.P. andDardis, G.F., editors, Geomorphology of southernAfrica. Johannesburg: Southern Book Publishers,198-230.

— 1990a: La corrosion chimique et sa significationdans l’évolution des paysages (trans. Y. Lageat). InLa terre et les hommes. Mélanges offerts à Max Derruau.Clermont-Ferrand: Association des Publications,Faculté des Lettres de l’Université Blaise Pascal,

nouvelle série, fascicule 32, 317-34.— 1990b: The origin and implications of some

erosional landforms. Journal of Geology 98, 343-64.Twidale, C.R. and Bourne, J.A. 1978: Bornhardts

developed in sedimentary rocks, central Australia.South African Geographer 6, 35-51.

Twidale, C.R. and Campbell, E.M. 1993: Fractures:a double-edged sword. Zeitschrift für Geomorphologie,37,459-75.

Twidale, C.R. and Centeno, J.D. 1993: Landformdevelopment at the Ciudad Encantada, near Cuenca,Spain. Cuadernos de Laborotorio Xeoloxico de Laxe 18,257-69.

Twidale, C.R. and Sved, G. 1978: Minor granite-landforms associated with the release of compressivestress. Australian Geographical Studies 16, 161-74.

Twidale, C.R. and Vidal Romani, J.R. 1994: On themultistage development of etch forms. Geomorphol-ogy, in press.

Verstappen, H.Th. 1960: Some observations on karstdevelopment in the Malay Archipelago. Journal ofTropical Geography 14, 1-10.

Vogt, J. 1953: Erosion des sols et techniques de cultureen climat tempéré maritime et de transition (Franceet Allemagne). Revue de Géomorphologie Dynamique 4,157-83.

Wayland, E.J. 1934: Peneplains and some erosionallandforms. Geological Survey of Uganda, AnnualReport and Bulletin 1, 77-79.

Wilford, G.E. and Wall, J.R.D. 1965: Karst topog-raphy in Sarawak. Journal of Tropical Geography 21,44-70.

Wilhelmy, H. 1958: Klimamorphologie der Massenges-teine. Braunschweig: Westermann.

Williams, G.E. 1986: The Acraman impact structure:source or ejecta in Late Precambrian shales, SouthAustralia. Science 233, 200-203.

Willis, B. 1936: East African plateaus and rift valleys.Publication 470, Studies in Comparative Seismology.Washington, DC: Carnegie Institute.

Wopfner, H. and Twidale, C.R. 1988: Formationand age of desert dunes in the Lake Eyre depocentresin central Australia. Geologische Rundschau 77,815-34.

Yatsu, E. 1966: Rock control in geomorphology. Tokyo:Sozosha.

Young, R.W. and Bryant, E.A. 1992: Catastrophicwave erosion on the southeastern coast of Australia.

Impact of the Lahai tsunamis ca 105 ka? Geology 20,199-202.

Zernitz, E.R. 1931: Drainage patterns and their sig-nificance. Journal of Geology 40, 498-521.

Zwittkovits, F. 1966: Klimabedingte Karstformen inden Alpen, den Dinariden und in Taurus. Osterrei-chische Geographische Gesellschaft 108, 72-97.



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