Climatic change and early population dynamics in the Southwestern United States

QUATERNARY

RESEARCH

1,

59-71

Climatic

CYNTHIA

(1970)

Change and Early in the Southwestern IRWIN-WILLIAMS Received

r AND April

13,

Population Dynamics United States

C.

VANCE

HAYNES

’

1970

It is becoming increasingly apparent that the pattern of early human occupation of the Southwestern United States was strongly influenced by the major paleoclimatic events of the period 9500 B.C. to A.D. 700. The size of human populations and the distribution of human settlement at both the regional-topographic and large-scale area1 level, known from archaeological research, are directly correlated to climatic change documented by the evidence of geology and palynology. The effect of climatic change is felt through the actions and reactions of the economic subsystem and its linkages with other subsystems. These reactions reflect not only the character of the climatic stimulus but also the existing state of the cultural system. Alternate reactions include direct systemic readaptation to the changed environment (through changed technologies, methods of population control, etc.) ; or small scale or large scale relocation of populations in different local niches, regions, or areas whose character most closely approximates the conditions to which the cultural system was initially adapted.

preceramic Southwest, taken in conjunction with the rapidly accumulating contextual data from geology and paleobotany, suggests the skeleton framework of certain long-term cultural patterns. In the present discussion, attention is focused on certain preliminary indications concerning the long-term relation between human and natural ecology as reflected in large-scale (and therefore somewhat sketchy) demographic patterning. Its purpose is to point up the crude but remarkably close coincidence between certain major ecologic-climatic events, indicated by geology and paleobotany, and demographic events suggested by the nature and distribution of archaeological remains. It had its origin in preliminary attempts to plot distribution of certain published and unpublished preceramic materials in the Southwest, and in discussions between C. Irwin-Williams, C. V. Haynes, and P. J. Mehringer, whose re-

EARLY CULTURES AND CLIMATIC CONTEXT

The Southwestern United States is one of the richest and best known archaeological areas in North America. However, research to date has focused on the remains belonging for the most part to the periods after the birth of Christ. Data on the long period of cultural development before that time are relatively sparse, leaving enormous rents in the fabric of our knowledge. Existing information comes largely from incidental studies such as surface collections and excavations at single sites, although a few regions have received more systematic research. Despite its sparse quantity and variable quality, the available information on the 1 Eastern New Mexico University, Mexico 88130. 2 Southern Methodist University,

Portales, New Dallas, Texas

75200.

59

60

IRWIN-WILLIAMS

AND

search and syntheses provided information on the geochronologic and paleoclimatic context (Fig. 1). In this connection, it should be noted that since it is recognized that an archaeological culture, as a representative of a preexisting social reality, emphatically cannot be identified with or by a single class of artifacts (e.g., projectile points), every effort was made to acquire whole cultural information. Given the variable state of preceramic research, the quality of the available data was equally variable. Accordingly the reliability of information is highest in areas which have been intensively studied (e.g., north-

HAYNES

western New Mexico, southern and eastern Arizona, portions of southern California) and lowest in areas which have received little attention (e.g., central and western Arizona, southern Utah). It is hoped that the hypotheses presented here will stimulate new interest in these little-known regions. PALEO-INDIAN

ECONOMY

Before examining the character of the potential effects of climatic change on human popufations, a few comments are appropriate concerning the reconstruction of Paleo-Indian economy and the significance

TERN )RY 1 south

\

I’\ 7000

8000

FIG. 1. Schematic correlation between principal geologic units, climatic change in terms of effective moisture, and archaeological cultures in the Southwest, 9500 B.C. to A.D. 700. Right-left hatchure: Plains-based Paleo-Indian cultures ; Left-right hatchure : Southwestern Archaic cultures.

CLIMATIC

CHANGE

AND

of the distribution of certain large, now-extinct fauna1 species to the patterning of the earliest Southwestern cultures. Reacting against an earlier tendency to oversimplify such reconstruction and to over-emphasize the hunting aspects of Paleo-Indian economy, some scholars have underlined the probable role of small game and plant foods in Paleo-Indian subsistence and have minimized that of the larger species. While foraging activities doubtless did play an important part, it is felt that reaction against oversimplification may be carried too far and that excessive preoccupation with these aspects may result in losing sight of the essential orientation of many (not all) PaleoIndian cultures. The available evidence may or may not be a representative sample, but there is at present no justification for an a priori assumption that it is not, and for appealing to “hidden data.” In point of fact this evidence (in common with that for certain Upper Paleolithic cultures of western Europe) strongly suggests that the late Pleistocene and early post-Pleistocene populations of the American High PlainsSouthwest were strongly oriented toward hunting large game. Viewed systemically it suggests relatively well-integrated cultural systems whose economic structures were hased on a restricted mapping of the environment and on a selective exploitation of a relatively narrow spectrum of potential resources. Accordingly, these cultures were probably centralized around “lead-point” activities concerned with the exploitation of specific (often migratory) large game animals (Irwin, 1968; Irwin-Williams, 1970 ; Irwin-Williams et al., 1970). Basic to a consideration of the relation of human and natural ecology is the reconstruction, insofar as possible, of the environmental context for human development. Of critical concern for such studies of early human populations in the Southwest are indications in the paleobotanical record of fluctuations in amount of effective moisture,

POPULATION

61

DYiYAMICS

and in the geologic record of major episodes of erosion and deposition, fluctuations in available soil moisture, periods of soil formation, and climatic implications derived from this data. Employing data from geology, paleobotany, and archaeology (Haynes, 1968 ; Mehringer, 1967 ; Irwin-Williams, 1966, 1968a,c), it is possible to construct a diagram illustrating the principal correspondences between climatic events and the major archaeological units on a single exact-chronologic time scale (Fig. 1). With this background, it is possible to examine more closely these relationships. CLOVIS

CULTURE

The earliest well-documented assemblages in the Southwest belong to the widespread Clovis Complex. That no incontrovertible earlier remains have come to light in the Southwest certainly poses one of the most pressing unsolved problems in American prehistory. Haynes (1966) has suggested deep burial and rapid depositional buildup as two possible (but not sufficient) reasons for the paucity of early finds. Population size differential is also probably an important factor. However far back the inhabitants of this or other comparable areas may ultimately be traced, it seems probable that the sudden widespread appearance and short time span (about 9000-9500 B.C.) of the Clovis material in the western United States represents a considerable, perhaps a dramatic, increase in population over preceding periods and may have involved the penetration of regions never previously occupied by human beings. On the basis of the available archaeological and paleontological evidence, it seems possible that this population expansion reflects a successful centralized systemic adaptation toward the exploitation of a latePleistocene fauna1 assemblage, possibly centered around the mammoth but also including bison and possibly horse, sloth, camel, etc. It probably represents a departure

62

IRWIN-\VILLIAMS

from preexisting subsistence patterns (where present), which may have been less specialized and certainly less successful. Clovis materials occur in the geologic context of Deposition Unit B-l, and the evidence of pollen analysis indicates a somewhat more mesic environment characterized by more effective moisture than the present (Fig. 1). Evidently, a late-Pleistocene environment capable of supporting key economic fauna1 species existed over much of the Southwest. Southwestern Clovis materials and occasionally mammoth and bison

AND

HAYNES

remains have been recovered throughout New Mexico and Arizona and in smaller numbers well into California and the southern portion of the Great Basin (Fig. 2; Warren and Ranere, 1968; Tuohy, 1968; Agenbroad, 1967). While relatively few excavated materials with good fauna1 association exist, most of those available fall into the mammoth-dominated pattern. One site (Murray Springs), however, has produced Clovis materials in association with extinct bison (Hemmings, 1969). The relative sparsity of this material in certain areas (e.g.,

FIG. 2. Suggested distribution of Southwestern Cultures, . 9500 B.C. Pattern A: Plains-based PaleoIndian cultures ; pattern B : western-based Archaic cultures ; pattern C . Southern-based Archaic cultures ; pattern D : Great Basin Archaic cultures.

BC FIG. 3. Suggested

distribution

of Southwestern

cultures;

8500 B.C., (A-D,

see Fk

21.

CLIiV.\TIC

CII.\EGE

,\ND

California) may reflect a situation of marginal or temporary penetration, or the state of archaeological research, or both. LATER

PALEO-INDIAN

CULTURES

The break between Units B-l and B-Z, corresponding to a shift toward conditions of somewhat less effective moisture indicated by the paleobotanical evidence (Fig. l), apparently corresponds to a period of change, area1 shrinkage, and economic readaptation for the Paleo-Indians of the Southwest. The succeeding Paleo-Indian (Folsom and Piano) materials fall within the period of about 8500 to about 5500 B.C. and occur within deposition unit B-2, a pedalogical context which seems to indicate conditions of generally decreasing soil moisture. Pollen data for this period suggest a series of fluctuations in available effective moisture : ( 1) a cooler or more moist interval, or both (centered about 8500 to about 8000 B.C.), (2) a period of relatively less effective moisture (from about 8000 to about 6500 B.C.) ; (3) a brief return to more effective moisture conditions centered between about 6500 and 6000 B.C. ; and (4) finally, a long-term continuing trend toward decreasing moisture (though with possible internal fluctuations) after about 6000 B.C. The coincidence of these events and the suggested concurrent demographic fluctuations is very close indeed. The period of Folsom occupation from about 8800 to about 8300 B.C. falls largely within the period of increased effective moisture in Mehringer’s terms (Mehringer, 1967). Mammoth and several other members of the Clovis economic fauna1 assemblage had declined drastically or became extinct by the beginning of this period (ca. 8700 B.C.). Conditions were evidently very favorable to large herds of now-extinct bison. The evidence from both kill-sites and camp-sites suggests that the dependence of these later Paleo-Indian cultures on bison hunting was very great, though not exclusive, and that

POPVLATION

DYN.\MICS

63

the subsistence system may well have been strongly centered around bison ecology (,Irwin, 1968). Certainly the fluorescence and relative abundance of remains indicate a successful, probably specialized, economy tied to a relatively reliable food source. Remains of extinct bison in this period are rare or absent west of central Arizona. It is probably significant, then, that the area in which Folsom materials are found seems to extend no farther west than central Arizona at most (Agenbroad, 1967)) representing a considerable shrinkage over the preceding period in terms of area occupied by hunting-oriented Paleo-Indian cultures (Fig. 3). During the subsequent period, characterized by a trend toward relatively less effective moisture (from about 8200 to 6700 B.C.), the distribution of archaeological remains is instructive. At the beginning of this period, a further shrinkage in the area occupied by Plains-hunting cultures is evident. Agate Basin materials (from about 8300 to 8000 B.C.) overlap Folsom slightly in time but occur only rarely as far west as western New Mexico. The trend toward conditions of decreasing effective moisture continued during the Hell Gap and Alberta period occupations of the High Plains (IrwinWilliams et al., 1970). Materials of these complexes are absent entirely from western New Mexico and are rare or absent in the eastern portion of the state (Fig. 4). Their distribution is focused further north on the short grass High Plains of the northern United States and southern Canada (Irwin, 1968). In this connection it should be noted that certain western archaeological remains, probably belonging to the Lake Mohave or Jay complexes. have been identified mistakenly as “Hell Gap,” and have resulted in a spurious impression of Hell Gap distribution (Agogino, 1961 : Irwin-\;l’illiams, 1968~). Finally, the brief return to conditions of relatively greater effective moisture, which may have begun about 6700 B.C., is re-

64

IRWIN-WILLIAMS

AND

HAYNES

of Southwestern cultures, 7000 B.C. Pattern A: Plains-based PaleoFIG. 4. Suggested distribution Indian cultures ; pattern B : western-based Archaic cultures ; pattern C : southern-based Archaic cultures ; pattern D : Great Basin Archaic cultures.

FIG.

5. Suggested

distribution

of Southwestern

fleeted by concomitant responsive shifts in the pattern of human occupation. Remains of the Cody Complex occur over much of western New Mexico and evidently represent rather sparse reoccupation or frequent penetration of the area (Fig. 5). Subsequently, terminal Paleo-Indian cultures (for example, the Frederick Complex, IrwinWilliams et al., 1970) were confined entirely to regions east of the Rio Grande Valley. In summary, the fluctuating distribution of the later Paleo-Indian materials in the south-

cultures, 6500 B.C. (A-D,

see Fig.

BC 3).

western United States exhibits a pattern which corresponds remarkably closely to that for available effective moisture as indicated by geologic and paleobotanical evidence. It may be suggested that the most direct mechanism through which climatic conditions could have effected human demography at this period was the distribution of water sources and of large maximal herds of bison (not simply small groups or isolated animals) which played a basic role in the structuring of the subsistence system. The

CLIMATIC

CHANGE

AND

bison is not as sensitive a climatic indicator as certain microfaunal forms, and its total range during these climatic fluctuations may have been little effected. However, the areas of optimum conditions and the distribution of the large reliable herds upon which late Paleo-Indian economy may have been centered, may well have responded to the climatic shifts. If so, because of the high degree of systemic integration and centralization characteristic of late Paleo-Indian cultures, it may have been particularly difficult for these groups to adapt. Systemic mapping of the new diminished environment would have involved not only radical changes in the perception of the relevant environment and correlated economic system but also probably in the social and value systems as well. It seems probable that during the period of climatic change which characterized late Paleo-Indian and post Paleo-Indian times that these hunting-oriented Plainsbased groups were largely unable or unwilling to adapt to a mixed-foraging subsistence pattern in a marginal environment and withdrew to concentrate in areas where optimal conditions still existed. EARLY

ARCHAIC

CULTURES

Having indicated the broad outlines of the eastward shrinkage of the Plains-based hunting cultures during late-glacial and early postglacial times, it is now possible to consider contemporary events in the western Southwest. Early western cultures characterized by an eclectic, or at least less centralized and more adaptable economy, may be as early as the Clovis, Folsom, and Plano Complex in certain portions of the Southwest (Fig. 2-6). There is at present no acceptable evidence of any direct relation whatever between these early Archaic cultures and the Plains Paleo-Indian cultures, nor of their derivation from the latter (IrwinWilliams, 1968a). The coarse choppers and chopping tools from the Volcanic Debris level of Ventana Cave (Haury, 19.50) may date

POPULATION

DYii-AMICS

65

about 9000 B.C. ; the San Dieguito type site has now been dated as early as about 7000 B.C. (\\.arren, 1967, 196s) ; and the seedgrinding implements of the Sulphur Springs Cochise may date about the same period. Early centers for these developments may have been in southern California and northern Mexico. In California, the Lake Mohave-Silver Lake Complexes may be derived from a San Dieguito base or may be partly contemporary. Accumulating evidence now suggests a continuum of related materials of the Lake Mohave-Silver Lake and Jay (or Rio Grande) compleses extending from southern California north and east to north-central New Mesico. The Jay Phase of the Oshara Culture in the northern Southwest ( Irwin-l\“illiams, 1968a) evidently reached its eastern limit of distribution in northern New Mexico sometime between 5000 and 6000 B.C. (Fig. 6). The complexion of the Lake Mohave-Jay continuum and its chronology suggests the eastward penetration of the northern Southwest by western-based groups sometime after the abandonment of the area by the Plains-based Paleo-Indian cultures. The character of the San Dieguito, Lake Mohave, and Jay artifact inventories, site locations, etc., suggests that these groups may also have been dependent to some considerable degree on hunting. However, the subsistence pattern was evidently sufficiently flexible to adapt to changing conditions. Evidence is now available from northern New ;1Iexico (Irwin\Villiams. 196Sa) to suggest the slow shift to a mixed-foraging and ultimately, to a plant resource-oriented economy. In brief, although evidence is still inadequate for any firm conclusions, there are indications of the existence in the western and southern Southwest during this period of 6000-9000 B.C. of cultures distinct from the Plains-based Paleo-Indians (Fig. 2-6). These cultures, whether initially hunting- or gathering-oriented, were evidently economically flexible and capable of esploiting

66

BC FIG. Indian tures; Archaic

6. Suggested distribution of Southwestern cultures, 5500 B.C. Pattern A : Plains-based Paleocultures : pattern B : western-based Archaic cultures ; pattern C : southern-based Archaic culpattern D : Great Basin Archaic cultures; pattern E : poorly known north-Mexican-based culture ; distinct from C.

FIG.

7.

Suggested

distribution

of

Southwestern

the environmental niche abandoned by the Plains-based groups during this long-term trend toward conditions of decreasing effective moisture. The period of about 5500 B.C. to 30003500 B.C. is represented geologically by the erosional surface separating geologic Units B and C and by the deposition of Unit C. Paleoclimatic evidence for this, the Altithermal Period of Antevs (1955), is accumulating to suggest conditions of considerably less effective moisture (Mehringer, 1967; Haynes, 1968; Malde, 1964) than the

cultures,

4500

B.C.

(A-E,

see Fig.

6).

present. Archaeologically, this is the least well known of all periods in the prehistory of the Southwest (Fig. 6 and 7j. Indeed, many areas present an essential blank for this time period. Limited evidence suggests that total abandonment of the area did not take place. Indeed, in relatively favorable areas, such as northwestern Kew Mexico, the continuity of occupation is maintained throughout : The Bajada Phase (4800-3300 B.C.) succeeds the Jay Phase (ca. 75004800 B.C.) in Oshara development, and presents indications of economic readaptation

CLIMATIC

CHANGE

.\ND

toward a more eclectic economy (IrwintVilliams, 1968a,b,c). In the western Southwest, some portion of the Lake MohaveSilver Lake material day date from this period. However. in some areas, particularly in the southern Southwest, even when relatively well known archaeologically, reliable evidence dating from this period is very rare, and the circumstances may reflect a very sparse population indeed. For example, to date there is no completely acceptable evidence of the Cochise Culture between 3500 and 5500 B.C. (IrwinWilliams, 1968~). It is possible that in marginal areas the human population became increasingly concentrated around the principal remaining resources, leaving large areas subject to only marginal or temporary occupation. LATER

ARCHAIC

CULTURES

The period between 2500 and 3500 B.C is represented in the geologic record by the formation of the soil on deposition Unit C, and by palynologic evidence suggesting a marked trend toward conditions of greater effective moisture (Fig. 1). At the same time there are considerable indications of a rather dramatic population increase all over the Southwest (Fig, 8). This is represented by assemblages such as the early Chiricahua Cochise, early Pinto Basin, and early San Jose. It seems possible that the existing economically eclectic Southwestern cultures, conditioned to maximum exploitation of an environment of scarcity, underwent important expansions with the amelioration of resources brought about by increased effective moisture. For the succeeding period from about 3000 B.C. to A.D. 1 the archaeological evidence is sufficiently abundant that derivative hypotheses are on much firmer ground than those presented for earlier developments. This period, corresponding to the formation of a soil on Unit C and the deposition of Unit D-l, was one of generally greater effec-

POPULATION

DYiVAMICS

67

tive moisture, declining, however, in the centuries just before the birth of Christ. During the period represented by deposition Unit D-2, there is now good archaeological evidence for the occupation of the entire Southwest by a broad continuum of related cultures which has been termed elsewhere the Picosa or Elementary Southwestern Culture (Irwin-Williams, 1967). This is certainly the first time in prehistory in which the Southwest may be considered a distinct culture area. 1Vithin this culture area, three distinct but closely related subdivisions have been recognized : the western or Pinto sector of southern California and adjacent Arizona and southern Nevada ; the closely related and continuously distributed northern, San Jose ( Oshara) sector of southeastern Utah, northeastern Arizona, northwestern New Xlexico, and southwestern and parts of central Colorado ; and the distinctive southern Cochise sector of southeastern Arizona and southwestern and west central New Mexico. Of considerable interest is the apparent continuing northward expansion of the Cochise culture, first into east central Arizona and west central NewMexico (about 2000 B.C.), and subseqently (with the addition of certain hlogollon characteristics) into the northern Rio Grande and its tributaries shortly after A.D. 1 (Fig. 9 and 10). The available data suggest that the basic economy throughout the area was one based on plant gathering and foraging with incipient horticulture present in the Cochise and San Jose ( Oshara) areas by ISOO2000 B.C. In the Oshara area the inception of agriculture, possibly correlated with another trend toward increased moisture, as yet incompletely known, is accompanied by notable shifting in local settlement patterns, trending toward economic seasonality and generally increased population. In all three areas an internal temporal cultural division falling at about SOO-SO0B.C. can be recognized. At about this time, the San Pedro

IRWIN-WILLIAMS

GS

AND

HAYNES

BC nf Southwestern cultures, 3000 B.C. Pattern A: Plains-based PaleovYy,,,
0 o.

r .._--__ ~uggc>~cu

r.3

,l:,+r;h..+;nn ULJLALVUL~~,,

BC J+.. 9. suggested

distribution

of Southwestern

phase of the Cochise evolved from the preceding Chiricahua in the south; the Rose Spring phase from the late Pinto in the west; and the En Medio phase from the preceding late San Jose or Armijo phase of the Oshara Culture in the north. SubseNew Mexico, quently, in northwestern during the late En Medio phase (about 300 B.C. to A.D. 400., including those remains

cultures,

l-2000 B.C. CAPE) see Fig

. 8).

frequently termed Basketmaker 11 j there are indications of a continuous local shift in settlement pattern, of considerable populaand of a greater reliance on tion expansion, horticulture. Whether this pattern is paralleled in the western sector is not known. However, it seems probable that the numerous remains of the late San Pedro Cochise and early Mogollon cultures in the south

CLIMATIC

CHANGE

AND

POPULATION

69

DYNAMICS

AD FIti. IO. Suggested distribution of Southwestern cultures, AD. UilOO. Pattern ‘4: P ains-based PaleoIndian cultures : absent; pattern B : western-northern Archaic cultures ; pattern C : southern-based Archai c and derivative early ceramic cultures; pattern D : Great Basin Archaic cultures; pattern E: poorly known north-Mexican-based Archaic culture and derivative early ceramic cultures ; distinct from C.

reflect similar events. It is significant, then, to note that this population expansion corresponds closely to a brief return to conditions of more effective moisture, which evidently followed the climatic event termed the Fairbank Drought (Antevs, 1955). A final local shift in settlement pattern in northwestern New Mexico which falls in the time range under discussion evidently occurred near the end of the Basketmaker III period (about A.D. 700). The shift is evidently closely related to a brief period of conditions of rather drastically decreased effective moisture which may correspond to -4ntevs’s White-water Drought (Antevs, 1955), and to the stratigraphic unconformity separating geologic Units D and E. In the northern Southwest, this was a period of disastrous arroyo cutting which apparently utterly destroyed the available alluvial farmland in many of the narrower drainages and probably resulted in a lowered water table in many others. It saw abandonment of localities which had been more or less continuously occupied since San Jose times and .a reconcentration of population in broad

alluvial valleys especially favorable to an economy increasingly centralized around agriculture. Research on the later ceramic periods of the prehistory of the northern Southwest has shown a continued close relation between climatic change and human demography (Schoenwetter and Dittert, 1968). Although information is lacking on parallel population movements elsewhere in the Southwest, this probably represents an absence of research rather than an absence of evidence. SUMMARY In summary, then, although data are still very scarce and, accordingly, derivative hypotheses still speculative in the extreme, it is becoming increasingly apparent that the pattern of early human occupation of the southwestern United States was strongly influenced by the major paleoclimatic events of the period 9500 B.C. to A.D. 700. The principal parallels which are recognized at this time are as follows: (1) The maximum area of the Southwest occupied by putatively Plains-based, hunting-oriented cultures oc-

IRWIiX-WILLIAMS

70

curred during a period (9000-9500 B. C.) of relatively greater effective moisture than any period since that time. (2) The general fluctuating trend toward decreased effective moisture between 9000 and 6000 B.C. is reflected in an eastward shrinkage of Plainsbased hunters. Two fluctuations toward more effective moisture within that trend at about 8500 B.C. and about 6500 B.C., are mirrored respectively by the area1 extent and relative density of the Folsom Complex and the brief expansion of the Cody Complex. (3) Following the withdrawal of Plains-based hunting cultures (about 8500-5500 B.C.) the Southwest was occupied by Archaic cultures expanding from probable early bases in the west and south. (4) Subsequently, the period of climatic stress termed the Altithermal (about 5500-3000 B.C.), although not well

AND HAYNES

known, may have been paralleled by a shrinkage in human population, with concentration around remaining available resources. c.5) A return to conditions of relatively more abundant effective moisture about 3000-300 B.C. was correlated to a dramatic increase in human population, and the development of the Southwest as a recognizable culture area comprising a continuum of related cultures. The introduction of the knowledge of horticulture into the southern and northeastern Southwest resulted ultimately in the development of sedentary culture. (6) A final period of erosion and decreased effective moisture about A.D. 700 evidently caused widespread regional dislocation in the northern Southwest and probably in other areas.

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the

Arizona

Academy

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3.

IRWIN, HENRY (1968). “The Itama: Early Late Pleistocene Inhabitants of the United States and Canada and the American Southwest.” Doctoral Dissertation, Harvard University, Cambridge.

IRMN-WILLIAMS,

C. (1966). “Natural Ecology

and Population Dynamics in the Southwestern United States.” Paper presented at the Meeting of the Society for American Archaeology. IRWIN-WILLIAMS, C. (1967). Picosa : The elementary southwestern culture. American Antiquity 32, 441-457. IRWIN-WILLIAMS, C. (1968a). “The Oshara Tradition: Origins of Anasazi Culture.” Paper presented at the 1968 Meeting of the Society of American Archaeology. IRWIN-WILLIAMS, C. (196813). The reconstruction of archaic culture history in the southwestern United States. Symposium of the Society for American Archaeology. Eastern New Mexico Ulkersity Contributions in Axthropology 1, 19-23. IRWIN-WILLIAMS, C. (1968~). Archaic culture history in the southwestern United States. 1+k “Early Man in Western North America,” Symposium of the Southwestern Anthropological Association. Eastern New Mexico University Corctributions

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IRWIN-WILIAMS, C., IRWIN, HENRY, AGOGINO, GEORGE,and HAYNES, C. VANCE. (1970) “The Succession of Paleo-Indian Cultures in the Hell Gap Valley, Wyoming.” In Press. MALDE, HAROLD. (1964). Environment and man in arid America. Science 145, 123-129. MEHRINGER, P. J. (1967). Pollen analysis and the alluvial chronology. The Kiva 32, 96-101.

CLIMLIATIC

CHANGE

AND

JAMES, and DITTERT, A. E. (1968). .4n ecological interpretation of Anasazi settlement patterns. Zfz “Anthropological Archaeology in the Americas,” The Anthropological Society of Washington, Washington, D.C. pp. 41-66. TUOHY. DONALD R. (1968). Some early lithic sites in western Nevada. ZH “Early Man in Western North America,” Symposium of the Southwestern Anthropological Association. Eastern LVe-~ Mercico Unizlel-sity Contributions in Anthro~ology I, No. 4, 27-38. Wz\RREP;. CLAUDE (1967). The San Dieguito Complex : A review and hypothesis. American dntiqflit? 32, 168-185.

S(:HOEN\VETTER,

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CL.?UDE (1968). Cultural tradition and ecological adaptation on the southern California coast. Ix “ilrchaic Prehistory in the Western United States,” Symposium of the Society for American Archaeology. Eastern New Mexico Uuizversity Colltributiom in Anthropology 1, So. 3, l-14. WARREN, CLAUDE E., and RANERE, ANTHONY J. (1568). Outside Danger Cave: A view of Early Man in the Great Basin. In “Early Man in Ll’estern iYorth America,” Symposium of the Southwestern Anthropological Association. Easter?, Nczw Mexico C’rtiwrsity Contributions in

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1. x0.

3, 6-H