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BIOGEOGRAPH Y

BIOLOG Y COLLOQUIUM 1947

OREGON STATE CHAPTER OF PHI KAPPA PH I OREGON STATE COLLEGE + CORVALLIS i 1947 Eighth Annual Biology Colloquium Saturday, April19, 1947

BIOGEOGRAPH Y

OREGON STATE CHAPTER OF PHI KAPPA PH I OREGON STATE COLLEGE i CORVALLIS s 1947

TABLE OF CONTENTS

Page Foreword . 3 Colloquium Committees 3 Discussion Leaders 5 Chairmen of Sessions . 5 Opening of the Colloquium 5 Biogeographical Principles, Ernst Antevs 7

Paleobiology of North America, E . L. Packard 10 Origin and Distribution of North American Plant Formations , R. F. Daubenmire 17 The Phytogeography of the Northwestern States, Morton E . Peck 22 The Origin and Distribution of Living North American Mammals , Kenneth L. Gordon 25 Pleistocene and Postglacial Climate and Chronology, Ira S . Allison 32

Early Man in the Pacific Northwest, Erna Gunther . 39 Biogeographical Problems in North America, Ernst Antevs . 43

FOREWOR D

The Biology Colloquium is conducted in a ers ant themes of succeeding colloquia have been : spirit of informal discussion and provides oppor- 1940, Dr. Homer LeRoy Shantz, chief of the Di - tunity for participation from the floor . The col- vision of Wildlife Management 'Of the United loquium is sponsored by the Oregon State Chapter States Forest Service, theme "Ecology" ; 1941, of Phi Kappa Phi with the collaboration of Sigm a Dr. Cornelius Bernardus van Niel, Professor of Xi, Phi Sigma, and Omicron Nu. Sigma Xi as- Microbiology, Hopkins Marine Station, Stanford sumes special responsibility for the colloquiu m University, in collaboration with Dr. Henrik l inch on. Phi Sigma and Omicron Nu provid e Dam, Biochemical Institute, University of Copen - Jf!ternoon tea . The College Library arrange s hagen, theme "Growth and Metabolism " ; 1942, special displays of the writings of colloquiu m Dr. William Brodbeck Herms, Professor of Para- leaders and notable works on the colloquium sitology and Head of the Division of Entomology theme. and Parasitology, University of California , Grateful acknowledgment is made of the co - theme "The Biologist in a World at War " ; 1943, operation and interest of the several faculties o f Dr. August Leroy Strand, Biologist and Presiden t Oregon State College that are concerned wit h of Oregon State College, theme "Contributions o f biology, of those biologists contributing to th e Biological Sciences to Victory" ; 1944, Dr. George program, of Chancellor Paul C Packer, Presiden t Wells Beadle, Geneticist and Professor of Bi- A. L. Si*,'matother- executives of Oregon ology, Stanford University, thkme "Genetics and State College . the Integration of Biological Sciences " ; 1946, The first Biology Colloquium was held Marc h Dr. Robert C. Miller, Director of the Californi a 4, 1939, with Dr. Charles Atwood Kofoid of the Academy of Sciences, theme "Aquatic Biology ." University of California as leader, on the them e Because of wartime travel conditions, the 194 5 "Recent Advances in Biological Science ." Lead- Biology Colloquium was omitted.

COLLOQUIUM COMMITTEES EIGHTH ANNUA L BIOLOGY COLLOQUIU M COLLOQUIUM COMMITTE E SIGMA XI EXECUTIVE COMMITTEE HENRY P . HANSEN 'E. L. PACKAR D (chairman ) (president) W. E. LAWRENCE E. A. YUNKER (deitased ) (vice president ) i- IG •, - I . S . ALLISON FRANK H. SMITH DELMER M. GOODE (secretary ) K. L. GORDON W. H. IPAUL H. A. SCULLEN (treasurer ) DOROTHY DURS T VIRGINIA WEIMAR LEANOR LOCHER JW.,ILJEBERG PHI SIGMA EXECUTIVE COMMITTE E DOROTHY MITCHELL ALVIN R. Aura PHYLLIS THORN E (president) MARIAN OTT H. A. SCULLE N (vice president ) PHI KAPPA PHI EXECUTIVE COMMITTE E MARGUERITE COOK (secretary-treasurer ) -; - DAN W. POLING (president ) DOROTHY STEWART (secretaiy7r OMICRON NU EXECUTIVE COMMITTE E JUNE JARMIX JANET JOHNSO N (assistant secretary) (president) KATHERINE HUGHES CORINNE HANSO N (journal correspondent ) (secretary ) EDWARD VIETTI DOLORES BRACKEN (piesildEnLe!'ent I) , , ` 1'II MAyBEL .W.' OIsT.S1011sr' ter! ' .+ Jam=-1 ■~ ..r '(past president . ` ''''J - 1 . ERNST ANTEVS, Ph.D . Leader of Eighth Annual Biology Colloquium

Eighth Annual Biology Col1oqui m Theme: BIOGEOGRAPHY

Leader : ERNST ANTEVS, Ph.D., Research Associate, Carnegie Institution of Washington

Discussion Leaders : Chairmen of Sessions :

z SHIMMIN ALLISON, Ph .D., Professor of Geol- HENRY P . HANSEN, Ph .D. ogy, Oregon State College. Professor of General Science, Oregon State• ,C.l- lege (opening session) . REXFORD F. DAUBENMIRE, Ph .D., Associate Profes - sor of Botany, State College of Washington. JOHN GRANVILL.E JENSEN, Ph .D. Professor of Geography, Oregon State Colleg e KENNETH LLEW.ELLYN GORDON, Ph.D., Professor o f (second morning session) . Zoology, Chairman of Department, Orego n IVAN PRATT, Ph.D. State College . Associate Professor of Zoology, Oregon State College (luncheon session) . ERNA GUNTHER, Ph.D., Professor of Anthropology, Director of Museum, Executive Officer, Depart- JOHN R . ROBERTS, Ph .D. . ment of Anthropology, University of Washing- Professor of Biology, Pacific University ton. (first afternoon sessions) . LUTHER S . CRESSMAN, Ph.D. EARL LEROY PACKARD, Ph.D., Professor of Paleon- Professor of Anthropology, University of Ore- tology, Head ar Department of Geology, Oregon gon (second afternoon session) . State College. . DAN WILLIAMS POLING, M .S . MORTON E. PECK, Sc.D., Curator of Herbarium , President of Oregon State Chapter of Phi Kap-- Willamette University : pa Phi (evening session) . }

. DR. HANSEN : On behalf of Phi Kappa Phi, and I think it has been liberalized here at the I welcome all of you to the 1947 Biology Col- College so that the speakers can expect those in loquium. A welcome to you on behalf of Orego n the room to break in with a pertinent question State College will be extended by President A. L. any time they wish. Strand. So, I am happy on the part of the institution to welcome all of you here. It seems that most PRESIDENT STRAND : Dr. Hansen, ladies and times at this meeting, we have very nice weather. gentlemen, visiting speakers, .:and guests : The It was a little cool this morning, but I see the sun Biology Colloquium has been from the very start has come out. At one of the recent colloquium s a rather important part of the activities at Ore- with such beautiful weather, we found that- it was gon State College, and has proved its worth . I claimed by the speaker from California . But dont doubt that any speaker from afar who is were glad to have all of you here, and I am sur e invited. to take part in the Oregon State College that those in charge for Phi Kappa Phi, Sigma Biology Colloquium-unlesk it is immediately ex- Xi, and Omicron Nu have arranged a very worth- pllained. to him-runs to a dictionary to find out while program. what .difficulties he is getting into, because it cer- I suppose it is up to me to say some kiei!l of tainly affected me that way the first time I heard a word in regard to things in general. The. : the word. But evidently it is a very good Lat - thought occurred to me, in relation to the Chief word, and it means an open - discussion or an eV. motive of this meeting, that there hasalway :s been change of views-sort of a semiformal discourse, an unbalance between the world of things and "

6 BIOGEOGRAPHY Morning Session the world of thought. That is, our understandin g about them. Certainly nothing has set huma n of things never quite catches up with the truth . beings back on their heels more and started them It doesn't make any difference what field you g o to thinking than the work on this time scale for into, the scientists have long been at it, but th e the world that has been developed in about the social scientists are coming to it. last hundred years . We're struck today by the recognition, th e I believe our chief guest at this session o f general recognition of the interrelatedness o f the Colloquium is primarily interested in this tim e all things. If you attend a meeting of the Unite d scale as it can be recognized from things that we States Chamber of Commerce, you will run int o can see now in relation to what has transpired i n it. If you attend a meeting of agricultural lead- the Last 40 to `7'S'# iousand years. Our own Dr. ers, you will hear'someone talking about the inter - Hansen here has made some great contributions relatedness of all things . For instance, agricul- to that field, relative to forest succession in this ture, industry, and labor are so closely related region, and no doubt it is his primary interest i n that they must have regard for the other . This t that set the motive for this Biology Collo -

unbalance between things, the world of things " A IL! 6 and the world of thought, I suppose was eve r thus. No doubt the great contribution that bi- ologists, geologists, chemists, and physicists have. made in the last hundred years is to set up a nevn time t comes closer boll 4ruth~Uit$$ee the 1 things as they are a'ud omrc Teas = BIOGEOGRAPHICAL PRINCIPLE S ERNST ANTEVS

The modern geographical distribution o f quires appropriate food, water, and shelter . Other plants and animals is the result of many past and causes of spread are climatic changes, growth and present conditions and factors . Each plant or disappearance of ice sheets, rise of mountains , animal species had one or more areas of origin, submergence of land under water, and emergenc e from which it spread in all- directions as far as of land . A rise in temperature causes a pole- time and conditions permitted. The species o r ward migration of the life belts. It may open th e family originated within its modern area of oc- Bering Strait region to exchange of temperat e currence or reached it when one or more of the biota between America and Asia. Growing ice distributional conditions were different and per- sheets enforce migration. Submergence of land mitted it to do so. The present geographic rang e bridges, as the Panama region, causes mixing of may or may not coincide with the natural boun- marine life, and blocks spread of most land biota . daries of the species which may be expanding Rising of land bridges has the opposite effect (frequently at the same time retreating on on e and permits land dispersal . front), stationary, or retreating-on the road to The principal barriers or obstacles to spread extinction. of biota are of four main kinds : geographic, cli- Plants spread mainly by spores, seeds, an d matic, edaphic, and biotic. Among geographic fruits ; animals by eggs, larvae, and develope d barriers are ocean for land biota, continent o r animals. With few exceptions plants are passive isthmus for marine biota, and broad swift river s and depend on wind, water, and animals, es- for many animals. A strait that is occasionally pecially birds, mammals, and man for dispersal . frozen over is no barrier to some land animals ; Many animals, particularly insects and aquati c for instance, reindeer cross the 600 miles wide se a larvae, are spread passively. Occasionally many between Novaya Zemlya and Spitsbergen . Among kinds of animals are dispersed by wind, water , climatic barriers are temperature, precipitation, or on rafts of trees, sod or ice . Ordinarily, how- and duration and strength of sunlight . Obstacles ever, free-moving animals spread through activ e may be too high or too low temperature, too efforts by swimming, creeping, running or flying . much or too little precipitation, too much snow . The rate of spread varies greatly. Upon the Several barriers are neither distinctly geographi c melting away of the last ice sheet, the vegetationa l nor climatic but a combination of both . Among zones spread over Sweden as fast as the tempera- these are ice sheets, mountain ranges, plateaus, ture rise permitted, and they covered the country and the Grand Canyon in Arizona. Since tem- up to Lat. 61°, a distance of 400 miles, in about perature drops regularly with altitude a mountai n 3,000 years . The spread of many plants did not shows a vertical zoning of plant and animal lif e proceed step by step, but widely scattered outpost s comparable to the normal zoning with latitude. were established in favorable sites from which Therefore mountain ranges and plateaus are, be- explosive mass dispersal took place when the sides barriers, also peninsulas and islands of col d climatic conditions became favorable . The Neb- and temperate biota, frequently far equatorwards raska cottontail rabbit spread northward acros s of their general ranges. Conversely, the Gran d North Dakota between 1887 and 1915 and by 193 5 Canyon extends the desert far into a region o f was a nuisance in southern Manitoba . The Eng- juniper, pine, and fir . Edaphic, or soil, barrier s lish sparrow, introduced at New York City and are especially important for plants that are fa- in Nova Scotia, covered the entire settled Nort h vored by or dependent on particular soils, a s America in some 50 years . Weeds and insect those formed from limestone. Biotic barriers pests may also disperse over large parts of a con- include too stiff competition for a place to gro w tinent in a few decades . The Russian thistle has or for food, absence of suitable food in the form spread widely over the western United States and of vegetation or prey, lack of shelter and breed- Canada since its accidental introduction in 1886 . ing places, and presence of effective enemies , The first causes of spread or migration are parasites, and diseases. A very important facto r rapid multiplication and consequent competition is man, especially white man_ Since climatic con- for the means of subsistence . There is produced ditions influence or determine the vegetation , an abundance of seeds and offspring, and a plant some barriers are combined climatic-biotic . Such needs a suitable place to grow ; an animal re- are tundras, deserts, and some forests . 7

BIOGEOGRAPHY Morning Session Actual dispersal means not only physical time a Bering land bridge was established lietwee n spread of seeds or of animals, but developmen t America and Asia and has formed a highway fo r of offspring in the new territory that is estab- interchange of biota during most of the subse- lished. . quent ten million years. At times there has been . Thanks to their vitality plant% and anbials a shallow and narrow Bering Strait as exists to - have a certain specific tolerance and ada:ptiveness. --day. In the late Pliocene the rise of the Isthmu s Both can acquire ability to get along with littl e of Panama united North and-Sou h America after water. Kangaroo rat-s and prairie dogs are able separation throughout the earlier .Ce tozoic. This, to exist without even drinking. Both plants and separation and junction greatly. affected the iiiota animals store up food supplies. Both may be- of land and sea. come dormant during cold or hot-and-dry =am. . both the Rocky Mountains and- kb r Siierra Hibernating higher animals include amphibians , Iibada were peneplaned diuriig Ole: Miocene. In reptiles, some bats, ground squirrels, and bears . the Plio-Pleistocene the Rockies. worms upwarped In relation to physical environment most plants in a low arch to their modern lht. The Sierra and animals differ• inthe important respect that Nevada was in the late Upper l to ne, raise plants are fixed and have to endure or regulat e sufficiently to make the climate- in Nevada ar• i themselves to the extreme carnations of the site ; and after a. long quiet it was further uptilted sevA animals are mobile and j went eral thousand feet to near . its jresent height % them to a certain extetifirt. roe must Since t last great rise probably was assciat be more nearly adjusted to their environment, an d wiffi -the down warping of the Ttt+l_ar e they reflect it more accurately than do animals. in the southern San Joaquin Valley- arntd ,itch• Many animals escape the extreme weather condi- last climax of the Coast Range orogeny, it may tions in warm burrows or sheltered caves . Deer have occurred in the mid-Pleistocene . migrate in winter to lower altitudes for food an d The Cascades, according to Ralph Chaney, shelter. Caribou wander long distances . Birds, began to rise in the middle Miocene and were at especially insectivores and water birds, migrate the end of the Miocene high enough to have a seasonally thousands of miles ; many other birds, marked influence on the climate . They continued shorter distances . Reptiles stay in shady and coo l to rise throughout the Plio-Pleistocene. places when the sun is hot. Also the formation of the other main geomor- The order of importance of the natural bar- phic features of the West-the lava flows of th e riers to spread varies with the means and methods Columbia Plateau and their trenching, the fault- of dispersal and with the tolerance and adapt - ing and tilting in the Basin-and-Range province , ability of the plant or the animal to the different the uplift of the Colorado Plateau and the cuttin g barriers. For plants climatic barriers come first, of the Grand Canyon-began in the Miocene an d then edaphic, biotic, and geographic obstacles . has proceeded ever since. Temperature is on the whole more important tha n The Tertiary history of the climate in the precipitation. The plant associations have a zona l West is well known through the excellent studie s and regional distribution determined by climate . by Professor Chaney and his pupils . During the In case of mammals the order of the barriers is : Eocene the climate was warm temperate to sub - geographic, climatic, and biotic or environmental . tropical in Oregon, temperate in Alaska . It A few miles of salt water effectively bars mos t underwent a slow cooling, and by the Miocene mammals. Temperature is a close second renage was temperate in Oregon and most of California. factor. It determines the general distribution Upon the rise of the Cascades and the Sierra within a continent, while humidity influences th e Nevada the climatic conditions at the end of th e presence or absence in particular regions withi n Miocene also grew diversified with rainy west the temperature zones. slopes and dry east flanks and inlands . During All factors and conditions of distribution, al l the Pliocene the climate in west-central California , the barriers to spread, have undergone changes according to Daniel Axelrod, was first humid an d in the past, and these alterations h+a+sge s'et' 1'hrl r cooler than today, then drier and warmer, and mark on the modern ranges of the biota. Among finally cooler and moister than at present. past geographical changes are junctions and sepa- Since the Ice Age in the Sierra Nevada could rations of continents and oceans, upheaval o f have begun first after the large mid-Pleistocen e mountain ranges, wearing down of mountains , rise of the range, and since it seems comparabl e and emergence or submergence of low coastal to that of the northern half of the continent, there re io{ias awl eoat erntal shelves . In late Miocene may have been a long pre-glacial Pleistocene age L. -sue

Morning Session ANTEVS-BIOGEOGRAPHICAL PRINCIPLES 9 which in climatic respects perhaps fairly resem- In America no postglacial varved clay of an y bled the present. consequence is known ; but in northern Swede n The Pleistocene Ice Age was composed o f there is a varved Baltic bay silt which records alternating cold and mt} ages, each comprisin g the approximately 8,800 years that have elapsed several tens of thousands of years. The col d since the region became ice-free . In this sedi- 'ones had ice sheets _ io moderately high latitude s ment coarse silt marks the spring flood, fine sil t and glaciers in high nDuntains all the way to the the summer flow. Equator. They also had s .c. pluvial- or Pleisto- Assuming that major temperature variation s cene lakes in now arid regions . The mild age s -fluctuations comprising several hundred to a -the interglacials, interpluvials, and the Post- few thousand years-took place simultaneousl y glacial-were about as the present . These gen- in Europe and in North America, I have tried erally cold and mild ages were not uniform bu t to correlate stages and events in America with had many climatic variations ranging in duration their dated counterparts in Sweden and to con- from a few years to thousands of years . nect the partial American late glacial chronology The glaciations brought about several changes . with the modern time by means of the Swedish The glaciers and ice sheets grew relentlessly an d postglacial clay .,chronology . This i1 the origin drove away or exterminated all life in their path . of chronologies and time estimates I have pub- They immobilized so much moisture that the lished at various times . ocean level was lowered some 300 feet. By their Among important biogeographical change s weight they pressed down the earth's crust i n wrought by the glaciations were greatly changed amounts ranging from many hundred feet below edaphic conditions . The ice sheets mixed the old the large ice centers to zero just outside the ex- soils, the old debris mantle, and the newly forme d treme ice border. Among consequences of par- debris and deposited the mixtures, one part un- ticular biogeographical interest were submergenc e assorted and another assorted as to grain-size, o n of low glaciated land bordering on the sea, and land and in water . emergence of a string of islands off Massachu- During the terminal stage of the last Glacial , setts, Nova Scotia, and Newfoundland . As the man arrived in North America and became a n ice sheets melted, the depressed land gradually re- important biotic factor. During the past hundred coiled, the sea level rose, and the continental shel f years, particularly, the white man has severely islands were drowned . or completely upset the biotic balance by hunting, The waning ice sheets were bordered by many trapping, clearing of land, drainage, cultivation, lakes in which the fine outwash was widely dis- overgrazing, pollution of streams, and introduc- persed and settled6las glacial varved clay . Each tion of foreign plants and animals . summer a light colored layer of silt accumulated, Thus, during the Pleistocene glaciations and and every winter a dark colored clay lamina . The in historic time there have been exceptional letter was the fine fraction of the debris flushed changes with profound effects on the distributio n into the lake during the summer anelting, the par t of the biota . which settled so slowly that it came to rest o n the lake bottom first after several months . The SELECTED REFERENCE S silt layer and the clay lamina together forme d Cain, S . A. Foundations of plant geography. Harper & the annual deposit-a varve . In cross-sectio n Bros., New York, 1944 . varved clay resembles wood, only varves ar e Chaney, R. W., Carlton Condit, and Daniel Axelrod . usually from one-quarter of an inch to two inche s Pliocene floras of California and Oregon . Carnegi e Instn. of Washington Publ . 553, 1944. thick. The glacial varved clays have supplied data Scott, W. B. A history of the land mammals in th e for partial chronologies of the retreat of the las t Western Hemisphere. Macmillan Co., New York, ices in Europe and in North America . 1937. PALEOBIOLOGY OF NORTH AMERIC A E. L. PACKARD

A knowledge of the pal.ograp of , the Gent cannot usually be detected . A migration o f past not only contributes to a more complete the Proboscidia, for instance, from Alaska to understanding of ancient life but also assists in Florida, at the rate of only one mile a year, could interpreting the present day distribution of ani- have been accomplished in the Pleistocene in les s mals and plants: The task of picturing the world than ten thousand years . Beds containing the and its, life during past geologic ages falls to the same proboscidian species in Alaska and Florida, geologist, paleontologist, and paleogeographer. however, would probably be declared contempor- What group of scientists, perhaps better than aneous. others, recognizes that geologic time is exceed- Although events of the Pleistocene might pos- ingly long, and that almost inconceivably slow sibly be dated within ten thousand years, thos e geologic processes may in time produce stupen- of the Tertiary can seldom be arranged in chron- dous results. Slowly shifting seas, the imper- ological order unless separated by,, a million or ceptible rise of mountains, the slow reduction o f more years of time. In fact, the paleontologis t a continent by erosion are but a few processe s at present usually divides the seventy-five million s present in an ever changing world. These shift- of years of the Cenozoic time into intervals o f ing conditions necessitated changes in the living four or five millions and can thus present only organisms, individuals of which to varying de- about a dozen glimpses of the world and its lif e grees became adapted to a particular environment, during the Age of Mammals. were forced to migrate to more favorable locali- These pictures of the mammalian life of th e ties, or to suffer extinction. world have been greatly enriched by a paper by The paleobiologist has certain advantages ove r Dr. G. G. Simpson that appeared shortly afte r the student of modern life in the solution of some this paper was presented orally before the Col- of the distributional problems of a modern faun a loquium. The writer has, therefore, incorporated or flora. He often, through a study of a long below many data from that paper and is greatl y stratigraphic succession of sedimentary beds, is indebted to that author for his most significant able to recognize a sequence of changes in the study. physical environment of a . specific region extend- Since the emphasis of this Colloquium is o n ing, through a period of geologic time measured e f distribution of animals and plants, we shall b in hundreds of thousands, or even millions, o Concerned only with the land mammals, in rela- years. Wherever such sections of strata are fos- tion to their Cenozoienvironments . siliferous, he may detect progressive changes in the complexion of the biota ; evidences of increas- North America in early Tertiary had much ing adaptations ; suggestions as to phylogeneti c the general outline of today . Marginal seas cov- relationships or the evidences of migrations . ered the eastern portion of the southern Atlanti c Since the geologic record is nowhere com- states and northern Florida . An enlarged gulf plete, the geologist develops a composite geologic reached northward to the mouth of the Ohio . column in which each known section is repre- That sea spread westward into central Texas . sented in its appropriate chronological position . Paleocene and Eocene embayments from the Pa- The identification and correlation of strata from cific developed in California, Oregon, Washing- widely separated regions is ilgeelutwat rely ton, and southern British Columbia . upon their fossil content. It is now general'ly North -America was connected with Sout h recognized that life has slowly evolved throug h America, Asia, and possibly Europe during part more than a billion years, consequently the fauna of the Cenozoic . A land bridge connected North and flora of two widely separated geologic forma- America with the land mass to the south briefly tions could not approach identity of species un- during earlymost Tertiary, but it soon floundered less they were both living during the same geo- and left that continent long isrola:ttd frpmA . , • i logic moment of time . northern one. Alaska was apparent!y' br.wal, These geologic moments are exceedingly long connected with Asia, at - least at 4i -1es, sdt i in terms of human experiences . Even the time Paleocene and Eocene and later epees .- Coil c necessary for the slow peripheral expansion o f " Simpson, G. G ., Holarctic Mammalian Eauuas and Continent Relationships During the Cenozoic, Bul. Geol . Soc . Am ., Vol. 5 a mammal as it extends its range across a conti - pp. 613-688, July 1947 .

Morning Session PACKARD-PALEOBIOLOGY OF NORTH AMERICA 1 1 tion of northeastern North America with.-E trope study of the known faunas and floras preserve d has been postulated, but the evidence for itsrexist- in Paleocene and Eocene rocks . The absence of ence is not conclusive . mountain barriers west of t!ie Rockies, which The Central American and Bering region s could intercept the moist westerlies sweeping i n have long been recognized as unstable. James Paleocene and Eocene time across the western Perrin Smith in studies of the Triassic marin e portion of the continent, assured a more uniform faunas referred to them as portals, which fro m distribution of rainfall west of the a Cordilleran tine to time during the Mesozoic were open t o region. The absence of high bordering ranges, marine migrations and at other times were corri- and the deep Gulf embayment must have favore d dors available for migrations.- of land plants an d an equable rainfall and climate at least over the animals. The Cenozoic record of those portal s region of the Central and Atlantic coastal states . is, most significant since they were crossed by The prevailing oceanic currents were also mark- group after group of mammals. This is especially edly influenced by the configuration of the shor e true for the northern bridge . The southern one lines. Thus a land bridge to Asia would shut off remained closed to land types from early Paleo- arctic currents from the North Pacific and modif y cene until the early Pliocene, an interval of time the climate of the western margin of North covering a period of over fifty millions of years . America. - That Pliocene event initiated striking changes i n An estimate of an ancient climate based upon the mammalian fauna of the southern ntinent . fossil evidence rests upon the determination o f A north Atlantic connection during e early the optimum climatic subtype , now occupied , by Tertiary has been postulated largely... on the modern species or genera that are most closel y evidence of similar genera in Europe a North elated to the fossil forms, and the belief tll America. Simpson has recently shown that the the majority of the members of a well know n similarities in those early Eocene faunas might flora or .fauna have not markedly changed thei r be explained by migration roumrs across f'rAsia. climatic tolerances during the Tertiary. Paleo- Such relationships of North America with Europe botanists, therefore, confidently analyze a fossil and Asia are not in accord with the Wegener flora, and some, following Koppen, express th e hypothesis of drifting continents, which postu- postulated climate in formulas which indicate th e lates the separation of North America from minimum annual temperature, total precipitation , Europe by a westward drift which continued humidity, and distribution of rainfall, throughout during the Age of Mammals . This hypothesis i s the year. Such data, combined . with that from not yet fully accepted. various other sources, justify genlerali-zation cov- North America in the early Tertiary wa s ering the climate of the several epochs of the dominated by the _roughly parallel folds devel- Age of Mammals . Immediately following th e oped along the cor~illeran region during the Lara- rise of the Rockies in late Cretaceous, the climat e mide orogeny. East +f those ancestral Rockies appears to have been cooler than during the pre- d lay a region of lower relief, which extended east- ceding period ; however, evidence indicates a sub- ward to merge with the then but recently pene- tropical to warm temperate climate before the plained surface of the former Appalachian Moun- close of the Paleocene in the middle latitudes o f tains. West of the Laramide ranges were the this continent, which persisted - throughout th e lower lands of the Colorado Plateau, Great asin, Eocene. The presence of fossil magnolia, palms, and Coastal regions. Many local down arps and figs as far north as Alaska, palms and croco- developed within the western part of the conti- diles in Montana, and many other occurrences of nent ,gnd became the site of terrestrial, or farther subtropical or warm temperate animals and plants west, of marine sediments, which in some in - whose nearest modern relatives live far to the stances have preserved the record of those early south of their fossil occurrences, support_ such- a times. Many of the early Tertiary basins of the conclusion. Even parts of Greenland during the West contain much volcanic ash, or more often , Eocene were covered with plants having at least fluvatile sediments, and some were sealed by lav a temperate affinities. During the first two or three flows from the many volcanoes then bordering epochs of the Tertiary, the known faunas and the Pacific. floras do not show evidence of zonation. The climatic conditions of North America The record of the mammalian life during the during the first two epochs of the Tertiary can Paleocene is -largely confined to that preserved .in be determined by, consideration of the topo- the various sedimentary basins of the Cordilleran graphical and geographical features and by a region, especially within the states of Montana,

. rr 12 BIOGEOGRAPH Y Moritung ~` simm4, ,-.d : - IL~ v Wyoming, Utah, and parts of New Mexico an d known on this continent, but by the Eocene tYny~,-:~ s. Colorado. Local deposits derived from the the n were living in Europe . At least two irngortant newly uplifted ranges have yielded a wealth o f families of these small primates van-O. widely mammalian fossils exceeded nowhere else in th e over the northern land masses . 4 Wherever-that.. world. order to which man belongs originated, -their ea.t.l Early Eocene mammalian faunas are know n history shows that the North American rep-rg from Europe, but the early history of that con- sentatives occupied an important place in the- evo- tinent is largely recorded in marine sediments an d lutionary development of the groelk Thy ,present consequently pre-Oligocene land deposits are rare . record fails to show evidence of a rrnemhr4f the At that early date, the ancestral Mediterranea n Primates living on this continent during la Eo- extended across southern Europe, through th e cene and the coming of man a few thcrosand near east and across southern Asia, including th e years ago. Some members of the taroid group, Himalayan region, and reached to the Pacific . however, must have found haven- in the trogica~ l Embayments reached northward from that sea forests of Central America until the opening of - into central Europe as well as southeastward fro m the Panaman Bridge afforded them access :Ea! the Atlantic. In late Eocene a narrow Ural sea South America, where they gave rise to. the Mapa- - advancing from the Arctic apparently serve d lidae and the Cebidae, the two modern families , for a short time, at least, as an effective barrier , of South American monkeys . - - ► preventing or hindering migrations of land form s Preying upon these early forest dwellers . were between Asia and Europe. members of several families of primitive car• The rise of the Pyrenees in Oligocene, th e nivores not far removed from their insectivorous Alps and related ranges a little later, and th e Cretaceous ancestors. These small-brained, ill- Himalayans in the Miocene, inaugurated the pres- adapted creodonts are first known from North ent day geographic unity of those land masses America, but by late Paleocene they appear in and favored the accumulation of terrestrial sedi- Europe and ranged over the holarctic region b e ments in which mid-Tertiary land faunas an d fore late Eocene, at which time the miacid di - floras were preserved. vision gave rise to true carnivores. Because of the different geologic histories o f The herbivores of those early times included the northern continents in Paleocene, close cor- the condylarths, a group of ungulate-like mammal s relation of the few localities on those continents with creodont-like skulls and teeth ill adapted fo r cannot be made with certainty with North Amer- vegetable diet. Among these Paleocene types was ican localities. Consequently the first appearances Phenacodus, known only from North America, of certain mammals in North America do no t whose earlier ancestor was close to the stock fro m necessarily indicate the place of origin of a give n which both the perissodactyles and the arteo . group. It is of interest, however, to call atten- dactyles later arose. Although these stem ungu- ;i tion to the early history of some of these earl y lates are not known as early in Eurasia, ther-e is. placental mammals known from North Americ a as yet no evidence as to their place of origin or ; and to attempt to determine their migration the direction of migration. routes. The early development of another primitiv e Early eutherian mammals have been found i n group of ungulates, the Notoungulata, in Soutltii Upper Cretaceous beds of Mongolia . Those tiny America, and recent discoveries of a few repre- insectivores appear to represent the stem stoc k sentatives in Eurasia and North America, n gait from which the higher placental mammals were suggest their origin on that southern core inert derived. Modern members of the order Insecti- rather than in Asia, as formerly proposed.` vora still retain a number of primitive character s The late Paleocene faunas of Amer ca;• also which enable the paleontologist to understan d contain the grotesque, gigantic, uintatheres with better primitive North American Paleocene fos- their limbs adapted to great weight and heads sils, which are so distantly related to the moder n adorned with peculiar bony protuberances . When shrews. The early presence also of primitive in- first named, that group of herbivores was corn - sectivores related to an ancestral European hedge- sidered North American, but they are now kn9wii hog imposes an interesting question as to place o f from Amin. Tr}rrre the evidence for free inter; origin and the migration of that group, long sinc e continental migration increases with rrnare inters; _ •tc- unknown in the New World . sive collecting. Another group long extinct in North America Although small fossil mammals often escape. includes the lemurs and tarsoids. They are first detection, true rodents and the lagomiorplis,. to-

Morning Session PACKARD--PALEOBIOLOGY OF NORTH AMERICA 13 which the hares and rabbits belong, were repre- The earliest horse, Hyracotherium, was then sented in the early Eocene faunas of North living in Europe and America. It soon disap- America and Asia . The older group, represente d peared without apparent issue in the Old World , by Ischyromyidae and 2f stem stock of the Sciuro- but in America its place was taken by the well morpha group of rodents which is also possibl y known early Eocene horse, Eohip pus, which gave close to the stock from which all true rodent s rise to the long lines of horses extending throug h arose, first appeared in the late Paleocene o f the Cenozoic up to the close of the Pleistocene . North America. By Eocene time, however, they The Eocene horses were obviously adapted to had a wider distribution . the semi-tropical forests as indicated by thei r From this brief mention of a few types, it i s teeth and feet. A little later the horses an d shown that the Paleocene fauna of North Amer- several other contemporaneous ungulates change d ica included primitive representatives of such the enamel pattern of their cheek teeth and de- familiar orders as Carnivora, Insectivora, Pri- veloped longer crowned teeth in adaptation to a mates, and Rodentia, but no modern families ar e change from the softer vegetation of the fores t represented among them. to the harsher grasses that were by late Eocene Other mammals belonging to groups long ex- and Oligocene spreading over the plains . tinct or to stocks out of which the more moder n The odd-toed ungulates of early Eocene also Eocene orders arose were also living in the semi - included the titanotheres (Brontotheriidae) . They tropical lowlands of North America. Their place appear to have arisen on this continent, but befor e of origin and direction of dispersal cannot b e the end of that epoch they had reached Asia . determined until more is learned of the contem- Another perissodactyle was the very primitiv e poraneous life of the other continents . late Eocene Eomoropus, whose mid-Tertiary de- It appears that free communication between scendant, Moropus, was one of Oregon's most North and South America, and with the Old grotesque mammals . That chalcothere possessed World, was possible in earliest Paleocene . It is claw-like hoofs, a horse-like body, and teeth sim- quite possible that an Asiatic and American con- ilar to the deciduous dentition of the contempo- nection prevailed during the entire epoch, and i t raneous Merychippus. is evident that there was free intermigration at The rhinoceroses, unlike the chalcotheres, wer e the close of that time division . a virile and highly successful group and, like th e The Eocene faunas of North America are bes t horses, were characteristic of the North American ' known from the Rocky Mountain states. They middle Tertiary fauna, They may well have include a long list of mammals which were bette r originated in North America where three of th e adapted to their .world than their predecessors . four earliest families first appear . By late Eo- Many of them were immigrants, and they re- cene they may be counted as migrants, afte r placed many of the then existing archaic types which they evolved races on both continents, be - before the close of the epoch . `A number of came adapted to diverse environments, and dis- forms appear earlier than elsewhere on this con- appeared from the New World at the close o f tinent but their place of origin still remains a the Pliocene. mystery . Among them are a primitive opossum ; an aplodont rodent ; several types of creodonts, In contrast to the aggressive and diversifie d including a genus close to ancestors of the tru e rhinoceroses were the conservative tapirs . Stocks carnivores ; a titanothere, three genera of primi- ancestral to the tapirs were living in Europe in tive rhinoceroses, an early member of the large Eocene, but it is not until John Day Oligocen e pig-like entelodonts, and members of the Erina- time that a small representative, Protapirus, ap- ceidae and Ischryomyidae. peared on this continent. By that date it had To this partial list of Eocene mammals whose acquired many of the tapiroid characters and, place of origin is unknown may be added other s since it has remained in the forests up to th e that can be listed as migrants, since they occu r present, it has changed but little in tooth and foot on both continents, some of which, at least, are characters . A tapir was living at Cape Blanco, believed to have entered North America fro m Oregon, in late Pliocene or early Pleistocene in Asia or, less likely, directly from Europe. These forests not unlike those of the redwoods of to - include representatives of ten orders not know n day. Although the tapir is now confined to the in the Paleocene, the more familiar of which in- tropics, a New World type lives at high altitude s clude the Insectivora, Primates, Rodentia, Car- in cool or cold climate, and thus may well hav e nivora, Perissodactyla, and Artiodactyla . been able to cross a northern bridge .

14 BIOGEOGRAPHY Morning Session By the close of the Eocene, the Perrisodactyla of Sheep Mountain below Picture Gorge on Joh n had become well established in North America , Day River. and by middle Tertiary they occupied many dif- The oreodons, a common name for two fami- ferent environments, which included beside the lies of "ruminating swine" like the camels, may forests, the savannahs and the then grass covered have arisen in Eurasia, but by the late Eocen e plains. These plains dwellers developed stream- they were represented only in America . The lined bodies, elongated limbs, modified feet, oreodons possessed a curious combination o f and semi-hypsodont teeth with infolded enamel artiodactyle characters, became adapted to a va- adapted for grazing on harsh grass. The riety of environments, evolved a score or more horses, as is well known, and the rhinoceroses to of genera which never left North America, an d a lesser degree, were represented in mid-Tertiary persisted until lower Pliocene . The true oreodon s by highly specialized cursorial types, with slende r were in Oligocene and Miocene times living upo n limbs and. reduced digits . The rhinoceroses, un- succulent vegetation along the streams of eastern like the horses, later evolved heavy ambulator y Oregon. Their relatives, the agriochoeres, par- types adapted to the lowlands, and one group alleling in one regard the chalciotheres, developed was adapted to a semiamphibious life . claws in place of hoofs, and like many higher Not all of the horses became plains dwellers , ruminants lost their upper incisors . for the large lateral hoofs of Hypohippus of the The camels, whose possible early Eocene Eu- Miocene and Pliocene of North America imply rasian ancestors were close to those of the oreo- a forest habitat, while its contemporaries pos- dons, also appeared in America in late Eocene. sessed only rudimentary side toes in adaptation Their subsequent history up to the Pleistocen e to hard ground. was confined to North America, after which the This wealth of perissodactyles in Nort h true camels migrated to Asia, and others round America during the Tertiary is in marked con- their way to South America via Central America . trast to. the paucity of artiodactyles in the Ne w World. Primitive members of the even-toed un- Thus during the first thirty-five millions o f gulates appear in Europe and North America in years of the Tertiary, the modern orders of lan d mammals had been established the early Eocene. Their place of origin is un- . With a few ex- known, but their subsequent history throughou t ceptions, the migrants during the earliest two the Tertiary is largely Eurasian . Although mi- epochs included most of the families and orders grants are known in each of the epochs of the which then formed conspicuous elements of ti e Cenozoic, the artiodactyls remained the dominant faunas of the northern continents. Except pos- herbivores of the Old World. sibly during the mid-Eocene, when fewer migrants are known, the early Tertiary mammalian fauna s The earliest suborder of these even-toed type s were Holarctic had teeth suggesting a mixed diet, implying, pos- . sibly, a distant relationship with the archaic stoc k The recognized greater dissimilarity betwee n from which the Creodonts arose . Out of one o f the mid-Eocene mammalian faunas of Eurasia those groups of ungulates arose the Suina, an d and North America might imply continental by late Eocene primitive pigs were living in North separation . The known migrants of that time America. One of the New World forms, Helo- include representatives of only one familyLeach hyus, appears to have been close to the true of Carnivora, Perissodactyla, and the Artiodac- swine, a group which never reached America and tyla. In contrast are fourteen North American which was also related to the early gigantic pig- families which were nonmigrants and some ten like entelodonts . The latter became a conspicu- others common to both continents with gener a ous element in the much later John Day fauna o f peculiar to one or the other land mass . Oregon. The peccaries, first appearing in th e Even at such times as the late Paleocene and Oligocene of America, possibly represent immi- early Eocene, known migrants did not include all grants derived from early Asiatic Suina . groups represented on these northern continents . The late Eocene witnessed the appearance i n This indicates, as does the stronger evidence fo r America of primitive ruminant groups, repre- later epochs, that other factors were operativ e sented by the small deer-like Hypertraglidae, th e besides the mere existence of a lend connection . oreodons, and the camels. The former wer e The climate, the available food supply along early migrants, but their direction of travel i s the corridor, the physical conditions near th e unknown. Their tiny teeth are not uncommon in bridge heads, the presence or absence of enemie s the highly colored rocks outcropping on the slope and competing forms, and the population pres-

Morning Session PACKARD-PALEOBIOLOGY OF NORTH AMERICA 1 5 sures are a few possible screening factoA whic h from the high latitudes . By late Miocene, how - determine which groups shall pass. ever, the climate had evolved sufficiently to brin g As long as the mild climates, as implied by about differences between the southern and more the northern extension of southern forests, pre- northern floras and faunas, a condition which be - vailed, climate must have been a less potent fac- came progressively greater as time advanced . tor than later in the Tertiary . The general low- The Bering bridge was open to heavy intero ering of the temperature throughout middle an d continental traffic during the early Oligocene. late Tertiary, and especially during the Pleisto- Many animals crossed but the direction of migra- cene, must have imposed climatic resIr isSions o n tion in many instances is uncertain . A numbe r many forms. The Pliocene migrants, for in- seemed to have traveled eastward, a few of which stance, were derived from principal groups the n may be cited : They include members of the Sori- living in the middle latitudes . The Pleistocen e cidae ; the Ochotonidae, a lagomorph group ; the forms known to have crossed from Asia t o rodent family Cricetidae ; and some Procyonidae America were high plains and steppe animal s and Mustelidae types. The Felidae, represented already adjusted to cool or cold climates of north - by Eusmilus, appeared and evolved later into the ern Asia. Climate, directly or indirectly, was true and false saber-toothed cats of the John Da). also effective in shutting out most of the Asiati c time. To this list of probable immigrants should late Pliocene and Pleistocene types from crossin g be added the gigantic pig referred to above . the tropics into South America . A possible not- Among them were the earlier representative4+ o f able exception are the proboscidians that arrive d the strange artiodactyles known as the ProtoceraQ earlier in the Pliocene and spread into the south - tidae, which in Pliocene time evolved into the ern continent . four-horned, deer-like Synthetocerus. The lower The time interval, measured in terms of some Oligocene fauna contributed but a few migrant s ten or fifteen millions of years between the Oligo- to the Old World . cene and early Miocene, may be considered fo r Some selective process at the Bering Porta l this purpose as a unit . During that time ther e prevented the then present Eurasian viverids,'an d appear® to have been but a single strong inter - for some unaccountable reason all of their de- continental exchange of mammals, which cam e scendants, from entering the New World. The at the beginning of the Oligocene. Although lim- Perissodactyla and the Artiodactyla availed them - a ited migration may have been possible through - selves only to a slight extent of the Northern cor- out that epoch and the first part of the next, th e ridor at that time, although both orders expande d evidence for such interchange is meager . The on their respective continents . faunas, including the John Day, for instance, are Late crossings in Oligocene were made by generally considered provincial, and to have arise n moles, the beavers, Proscuirus, and the Criceti- largely out of American stocks . dae. The American fauna developed distinctive No marked orogeny in North America is re- genera, older types became extinct, and the mam- corded for that part of the Tertiary. The rising malian life began to acquire a more modern Appalachian plateau was being dissected, and the aspect. ancestral Rockies were being materially reduced, Thus by the beginning of the Miocene, the and the derived sediments were deposited in loca l faunas of the two continents were generically dis- basins or spread eastward over the High Plains . similar. It is not probable that the Bering Porta l Farther west, local block mountains were risin g was closed during much of Oligocene time, bu t only to be partially buried in their own rock at least some screening effect was present an d waste. Lowlands then bordered the margina l continued until the middle Miocene, when stron g seas of the Pacific Coast . Volcanic activity was intermigrations were again resumed . pronounced and in places, as in central Oregon , At that time proboscidians and members o f ash deposits accumulated in great thicknesses an d the Cervidae appeared in America . The latte r entombed rich assemblages of enimals and plants . 'group was then represented in Eurasia by a basa l The climate was still warm but evidences o f stock of browsers from which the deer and gi- lowering temperatures are recorded in the floras , raffe were derived . The American newcomers the more tropical elements of whicl, then livdtl included Dromomery and "stocks which in the south of their Eocene northernmost occurrences . Pliocene evolved peculiar bony outgrowths of t h The evidence, however, of climatic zoning is un- skull three-horned or branching structures at t certain. Such a conclusion is no doubt partly due top of Ule torn, and a er . ev to the scarcity of both fossil faunas and floras Antilicapridae. In Asia a possible modern rela -

r

16 BIOGEOGRAPHY Morning Sessio n tive is the "musk deer." The true cervids, how- mals and plants. These disturbances culminatin g ever, arose from an Asiatic group, and failed t o in the late Pliocene are referred to as the Cas- reach the Americas until late Pliocene and early cadian Revolution . Pleistocene. The temperature of the high standing conti- The relative stability of the crust of North nents was further lowered and the Pleistocene America during the first three epochs of the Ter- was marked by four long glacial stages with mild tiary favored the lowering of the high land area s interglacial intervals. The extensive ice sheet s of the western part of the continent. In the later that mantled much of the northern portion of thi s Miocene crustal unrest is locally recorded in continent and the higher mountains farther south warping, gentle folding, and faulting accompan- imposed distributional problems to northern life ied by extensive volcanic activity . The Ancestral and determined many of the conspicuous feature s Rockies were then approaching base level . The of the present Holarctic faunas. During the suc- marginal seas were retreating and their aban- ceeding Ice Age, erosive agencies sculptured th e doned beds were being covered with terrestrial earth's surface to its present form of mountains , deposits . In the far West piles of basic lavas dissected plateaus, hills, valleys, and coastal were building a topographic barrier along the plains. present region of the Cascade Range, and ove r In the Upper Miocene, the intermigration o f extensive regions of the Northwest lava flood s mammals became more important than at any and ash deposits were accumulating in great thick- other time between then and the early Oligocene . nesses . The climate was cooling and under th e At that time three subfamilies of Insectivora, sev- rain shadows of the youthful Cascades and othe r eral genera of Carnivora, additional proboscidia, lesser ranges the vegetation changed and the red- a group of rhinoceroses and possibly members of wood forests gave way to deciduous forests o f the Sciuridae arrived from Asia . North America the middle Tertiary. Savannas were then re- may have contributed to Asia a beaver, a large placed by open grass-covered plains, and semi- canid, and the forest horse, Hypohippus . The deserts. slightly distinguishable early Pliocene wave of The widespread prevalence of volcanoes fa- migration that followed added more proboscidian s vored burial in ash deposits of animal and plan t and a few other mammals to America . remains at many localities extending from th e By mid-Pliocene the short-faced bears de - present High Plains to the Pacific . Thus Miocene rived from the arctotheres of Eurasia appeare d and early Pliocene fossiliferous localities of th e and reached Oregon in Rattlesnake Pliocene time . west are numerous and have yielded rich faunas A few other forms, principally rodents and car- and floras. nivores, crossed the Bering Bridge. None of During the late Miocene and culminating a t these represent modern genera . The great expan- the close of the Pliocene, the western part of the sion of the perissodactyls in America and th e continent was subjected to repeated crustal dis- artiodactyls in Eurasia strangely did not result i n turbances. The peneplained surfaces of the much interchange of those orders during the lat e Rocky Mountain area and the Great Basin re- Tertiary. Those groups which were developing gions were uplifted . Many uplifted and tilte d in middle latitudes, however, during time of cool- blocks arose in the southwest . The lowlying ing climates and shifting food supply may no t Sierran region arose, was tilted westward, an d have been able to cross a northern bridge . was bordered on the east by a great fault escarp- The late Pliocene migrants from Asia brought, ment. Fault block ranges arose in Oregon an d however, a number of modern genera includin g their tilted surfaces contributed debris to the Soxex, Martes, Lutra, and Cervus, and a prob- adjacent structural basins . Folding of marin e able hyaenid . sediments and other rocks resulted in the Pacifi c The opening of the Central American porta l ranges bordering the Pacific. in early Pliocene introduced new faunal elements These crustal movements of the late Tertiar y into South America which markedly affected th e were not confined to this continent . South life of that southern continent. Carnivores, America was joined to its northern neighbor i n camels, horses, tapirs, and proboscidians repre- early Pliocene . The rising mountains of Europe , sent some of the more conspicuous migrants into Africa, and Asia, and the Andean chain in South the southland . Ground sloths, glyptodonts, arma- America, were rapidly modifying the world en- dillos, and the Canadian porcupine found thei r vironment and markedly influencing the evolu- way northward, but only the latter is still livin g tionary trends and migration routes of land ani- as far north as Canada.

Morning Session DAUBENMIRE-NORTH AMERICAN PLANT FORMATIONS 17 The early Pleistocene interchange between have been open, only a selected few appear t o the Americas and Eurasia was very pronounced , have crossed from one continent to the other . exceeded only by that of the early Eocene . The This close geographic relationship or these north- list of temperate or north temperate mammals i s ern land masses thus has prevented the develop- a long one . Only a few will be cited : Lepus, ment of many restricted North American o r Sciurus, Ursus, Gulo, Felis, and Mammuthus . Eurasian groups. Possibly the oreodons may be Many of the northern Asiatic plains and stee p considered the only nonmigrant, and thus th e Artiodactyles also crossed into North America .n most unique North American mammal . Many They include wapiti, bison, musk ox, sheep, goats , others, like the horses, rhinoceroses, camels, siaga antelope, and others . pronghorns, and other less well known form s This brief sketch of the history of land mam- were characteristically North American but the y mals of North America covers some 75 millions developed wide ranging forms . Such character- of years during which the continent has been istic Asiatic mammals as the siaga antelope, hy- fashioned into its present form with its diversifie d aena, and even giraffe have appeared in America . topography and climate . At first, primitive, l The South American contribution has been mea- archaic mammalian stocks appeared followed b y ger ; the glyptodons, ground sloths, armadillos , more specialized and more closely adapted types . and porcupines were the most conspicuous . *it times, as in the Eocene, Oligocene, middl e Paleontology thus reveals a vast array of Miocene, and again in early Pleistocene, free com- riammals that arose, dispersed, and became munication between the northern continents fa- adapted to a variety of conditions according to the vored a most intimate intermingling of mammals . same physical and biological "laws" that now At other times, although the Bering Bridge may prevail.

ORIGIN AND DISTRIBUTION OF NORTH AMERICA N PLANT FO RYVI A T I O N S R. F. DAUBENMIRE

The modern vegetation of North Americ a lated freely from tropics to the Arctic Sea through presents a very complex pattern . In fact, the broad gaps between the continents, and the seas pattern is so complex that very little real prog- were enlarged so that they exerted a relativel y ress has been made either in the development o f strong influence upon terrestrial climates . Be- a widely accepted classification of this vegetation, cause of these three conditions heat and precipi- or in providing a quantitative explanation of th e tation were rather well distributed and moistur e boundaries of the units of which it is composed . conditions seem to have been adequate for meso- Only in the last few decades have sufficient geo- phytic* plants over nearly all the land surface . logic and paleontologic data accumulated to per- The chief geographic variations in temperature at mit a dynamic approach to North American plan t those times consisted of a gradient from hot to geography . This new historical perspective i s temperate in passing from the tropic! to the Arc- destined to have a profound influence in shapin g tic Sea, and a gradient from oceanic to mildl y an acceptable classification, for it provides a much continental conditions in passing from coasts to - deeper insight into the fundamental factors gov- ward the interior. When the whole of geologi c erning the distribution of plant formations tha n time is considered, this climatic pattern has bee n was heretofore possible . the norm for the earth. Major geologic cycles and vegetational history Each time this mild phase of the climatic cycle prevailed there appears to have been a great ex- According to the geologic record, the earth's crust has been alternately levelled by prolonged pansion of tropical mesophytic forest that came periods of erosion, then uplifted and wrinkled int to cover territory well beyond the limits of the o tropics. Beginning at the poleward margin o mountainous ridges by diastrophism. Whenever f Y this belt and the remaining land surface to th the first of these phases prevailed there were no e mountain chains left to offer significant interfer- Arctic Sea there was a belt of temperate fores t I ence with the movement of the lower atmosphere . ' Mesophyte is used here for plants growing where soil drought is lacking or ecologically insignificant because it affects Also, during these times ocean currents circu- only a very thin layer of the soil and for very short periods .

aV r

18 BIOGEOGRAPH Y

vegetation. In the sedimentary deposits that ac - the formation as a whole was distinctly more cumulated during these times there is little evi- heterogeneous in a taxonomic sense than any o f dence of the existence of vegetation types of truly its modern derivatives, but sociologically it wa s cold or dry climates at any latitude . far less differentiated than at present . Sequoia At the other extreme of the geologic cycles , was a very characteristic genus of this ancient during those relatively short periods when the temperate forest, but with it were Acer, Aesculus, continents were enlarged and bore massive moun- Carya, Corylus, Fagus, Juglans, Populus, Thuja, tain systems, climates were much more diversi- and many other genera common to modern tem- fied. Oceanic circulation to and from the Arcti c perate floras . By means of land bridges, particu- Sea was so feeble that little heat was carried t o larly across Bering Strait, Eurasia and Nort h that region and a great body of cold water sup- America pooled their temperate floras, and th e porting a vast ice floe accumulated . By inter- rich forest that resulted became circumpolar i n fering with free movement of the wind system s Eocene time. across the continent, mountains caused excessiv e When climates began their long trend of dif- water to be precipitated on their windward slope s ferentiation in Oligocene time, coolness force d and dry "rain shadows" to the leeward . Because the temperate forest to move to lower latitudes mountains tend to be located chiefly around th e and altitudes . This change of latitude made th e peripheries of the continents, they were effectiv e Bering land bridge no longer available to the tem- in keeping the temperature-regulating influence of perate flora, and from late Oligocene up to the =- the restricted seas walled off from the interiors , present, North American and Eurasian segment s so that temperatures in the interior fluctuated of the flora have evolved in isolation . widely with the seasons . Thus the periods o f The trend toward coolness was accompanied continental elevation were periods when climate by the development of aridity in the center of th e was differentiated into a mosaic of small area s continent, and as the temperate forest move d of highly contrasted types . At such period s southward in North America it was divided into vegetation has been correspondingly more diver- an eastern and a western segment which were sified. These severe climates speeded up evolu- separated by a dry unforested region. By Mio- tion, for they undoubtedly eliminated many bio- cene time the temperate forest had moved fa r types that had accumulated during the long favor - down on either side of the unforested midconti- able intervals . nental plains, the eastern segment occupying the It should be clear that the earths surface, it s area from approximately the 95th meridian t o climates, and its vegetation, at present all approxi- the Atlantic coast, the western segment extendin g mate the second of the two cyclic extremes de- from the Rocky Mountains to the Pacific coast . scribed. This state of elevation and differentia- In Pliocene time the Cascade Mountains rose , tion has come about by means of intermittent up- creating an arid intermountain region which prac- lifts of the earth s crust which have accumulate d tically eliminated the western segment of th e since approximately the middle of the Cenozoi c temperate forest except for a narrow strip alon g Era. During the late Eocene and early Oligocen e the Pacific to which it is still confined . Epochs the continents were nearly flat, and ex- • T . During Pleistocene time the extinctions of a u _a tensively invaded by seas . Climates were gen- many taxonomic entities from eastern and fro m erally moist, varying from hot to temperate . western segments of the North American tem- ! Starting in the Oligocene and extending throug h perate forest brought about their present state o f 1 • 1 1 t the Pleistocene Epoch various mountain systems sharp differentiation . The climate along the Pa- were formed at intervals, the present pattern of cific coast northward from central California re- climates and biogeographic regions unfoldin g mained moist enough to continue supporting tem- spasmodically with each of these diastrophi c perate forest because of the combined influences changes . of the fog belt, the predominance of on-shor e winds, and orogenic precipitation. Although tem- Mesophytic vegetation perate in its broader aspects, the climate here ha s In late Eocene time the temperate Mesophyti c been distinctly oceanic and quite different fro m forest occupied most of Canada, forming a broa d the continental climate of eastern North Americ a belt that extended northward to the shores of th e to which the other segment of the formation be - Arctic Sea and sent peninsula-like extension s came confined . The evolution of the western an d southward down the erosional remnants of th e eastern segments of the temperate mesophytic for- Cordilleras as far as New Mexico . At this time est has been accordingly different . At various

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Morning Session DAUBENMIRE-NORTH AMERICAN PLANT FORMATIONS 19 latitudes along the Pacific slope Sequoia, Li&o- occupy southern Florida and ,southern Mexico cedrus, Thuja, Tsuga, and Picea sitchensis gained. with, long strips trailing behind northward alon g ascendancy, although manygenera of angiosperm s the coasts from each . of these ,regions. .-Father (Acer, Cornus, Quercu.+ Rhododendron, etc. ) south, in the .Caribbean region and in Sotnt h 4i.stgd as subordinates to remind us o f America, it covers vast territory over which it ha s genetic ties with the eastern forest . Whereas the : .long dominated .* coherent remnants of the western segment of th e 7 temperate forest became domjnated by evergreen Cryophytic vegetation conifers and confined to the moist parts of the Tundra and taiga occupy equally cold regions , Pacific drainage, other genera of the old temper - the former being found only where winds ar e ate forest (e .g., Cercis, Juglans, Ostrya, Platanus, o too severe for the latter . Climates like these etc.) persisted in the arid parts of the Cordilleran probably existed in Paleocene time at the begin- region by evolving specialized riparian or xero- ning of the Cenozoic Era, but so far as we know phytic species. they had disappeared as a result of the peneplai 4 The eastern segment of the temperate forest , tion that had eliminated high mountains by Oligo- which at present occupies most of the United cene time. During late Eocene the borders Of States east of the 95th meridian, has retained the Arctic Sea appear to have had as favorable . morenof the characteristics of its early Cenozoic climate as is now found along the coast of Ore- precursor. The post-Miocene loss of the redwood , gon or of Massachusetts, judging from the kind s reduction in importance of Thuja, Tsuga, and of fossils found from Alaska to Greenland . Al-, Chamaecyparis, with a consequent assumption of though the modern tundra and taiga seem to havk _ dominance by deciduous broadleaved trees whic h arisen subsequent to this peneplanation, there i s are better suited than evergreens to the conti- little question but that the dominants of thes e nental climate, brought about a considerable trans- modern formations are deri formation of the forest in that region. There, as in the west, the formation has differentiated over quirements. most of its area to produce highly distinctive as- are incapable of m a sociations, each characterized by relatively fe w short a span as the post Eocene period, dominants . In the northerly portions Acer sac- dominants of tundra and taig a charophorum became variously associated with exhibiting little geographic dive r Tilia, or with Fagus, or with a combination o f type that would suggest a recen t Tsuga, Fagus, and Betula lutea. To the south a conclusion therefore seems inesca variety of associations dominated by Quercus and must have been a few localities, either a Carya took over the land. This differentiation borders of the Arctic Sea, or on low of the temperate mesophytic forest into its pres- mountains at low latitudes, where tundra ent group of sharply defined associations seem s taiga species could survive the mild c best explained as an effect of the rigorous lat e were so unfavorable to them in lat e Cenozoic climate in reducing the number of bio- early Oligocene time. types and ecotypes which had been accumulatin g Analogy with certain modern ecol over millennia, and had permitted species of nomena suggests possible refugia that m i early and mid-Cenozoic time to be represented sufficed, along the cool edge of the temp over a wider environmental range. ' est. Tundra plants might have per Unlike the temperate forest, the tropical Mes- slight irregularities in the land surface allo w ophytic Forest formation appears to have suffere d snows to accumulate deeply and therefore to pe little in the way of sociologic differentiation an d sist late in summer and so prevent c o conomic simplification during the Cenozoic Era. * Botanists have long pondered the prob beds containing leaves of trees now confin e 'A,t the time of maximum ryarmth in late Eocene, zone, intimately mixed with leaves of those which are . now nitely tropical . In early Eocene, for example, 41 per cent o iloras containing decidedly tropical elements oc - the forest species of northern New Mexico were tropical, in cen- tral Colorado the percentage was 35 end in southern Montana 15. 'eupied most of the United States and souther n Again, in Pleistocene deposits of Apigsana, M- apnolia ucnmittato .•Ca>:lada, sending a slender arm up the west coas and Arnendimaria recta are aseociated with Picea ghraca an d t to in:nu . Two hypotheses have been advanced to account fo r phenomenon! (1) heterogeneous topography may have allowed as + liar as the southern tip of Alaska . Because diverse communities to live close enough to a deposition area to thiis forest requires a frost-free climate, it wa s contribute debris to it, and (2) mane apeciea may have acctttau- lated in abundance of ecotypes during the long warm phases of fccrfeed to recede progressively southward during the geologic cycles, which were auhsequently reduced by the ex- tenuating climate of Pleistocene time . That is to say, wider eco- n sit of the great climatic metamorphosis that be- typic amplitude during the warm phase might well have resulted in less of an ecologic gap between temperate and tropical flora s garl in Oligocene time . Eventually, it came to Ann exists at present. % . ti

20 BIOGEOGRAPH Y from forest communities . This hypothesis i s when there were no great mountain systems . r~, supported by the fact that in the southern Selkirks However, there is evidence of taxonomic, floris- there exist today as topographic climaxes som e tic, and sedimentary nature indicating that dry well developed islands of alpine tundra on snow- regions have always been in existence, although patch habitats, as much as 4,000 feet below aver - they were probably small during wet phases o f age upper timberline. the great cycles, and have been moved about a s Evidence for the local persistence of taiga the climatic patterns have changed . There ar e vegetation is more definite . Fossils of Picea or also several theoretical possibilities that cannot b e Abies of Eocene age have been found sparingly on ignored. The possibility is quite good that dur- the Alaska Peninsula, and in the Rocky Moun- ing the wetter part of the cycles there were area s tain region from Utah to Wyoming and Montana . in the interiors of continents that did not get These refugia could have been individually quit e rainfall commensurate with their summer heat , small as shown by modern relics that occur be- so that they had an approximation of the summer- yond the climatic area favorable to taiga . In dry Mediterranean type of climate. Because of -northeastern Iowa, for example, there have per- increasing heat toward the equator the likelihood sisted to the present time several relic stands of of desert refugia persisting during these period s Abies balsamea accompanied by boreal shrubs, was greatest in tropical regions, for the highe r herbs, and mosses, that must have endured man y the temperature the more rainfall is necessary t o thousands of years of adversely warm climat e prevent drouth . Also, the Rocky Mountains wer e since the last glacier receded from that region . not com¢letely eliminated by the prolonged ero- These stands are all situated on north-facing sional period of the early Cenozoic, so that th e slopes, and similar habitats could have serve d area immediately eastward might well have re- equally as well as local refugia for taiga plants i n mained somewhat arid . late Eocene time. Today, however, in the lee of the Cordillera , Whatever the nature of the microclimates that from central Canada southward far down into permitted plants requiring cool environmenta l Mexico, is a vast region where moisture is to o conditions to survive mid-Cenozoic time whe n deficient for the growth of mesophytic plants o n cold macroclimates were not known to have ex- the uplands. The vegetation of this arid temper - isted, the progressive changes that took plac e ate region may be divided into four major cate- subsequently allowed these plants to emerg e gories : the xerophytic forest, chaparral, grass - from their refugia, cover increasingly large r land, and desert formations . The order of enu- areas, and finally consolidate to form vast circum- meration is one of increasing aridity-xerophytic polar belts. Taiga then tundra each in turn prof- forest occupying the least dry climates, and deser t ited from the Bering land bridge as it becam e the most dry. - available for intercontinental floristic exchang e Evidence provided by paleontology, togethe r with similar vegetation that was forming in Eu- with that provided by the distribution patterns o f r. - S rasia. Had it not been for this pooling of cold modern species, both point toward Mexico as th e climate species, the tundra and taiga floras would earliest point of assembly of most of those xero- undoubtedly be even poorer in species than they phytic types of vegetation that are now associate d are. with the dry area caused by the North American Glaciation during the Pleistocene repeatedly Cordillera. There is little doubt but that the ma- blotted out much of the territory occupied by jority of the dominant species of this vegetatio n tundra and taiga, but both quickly reoccupied the originated much earlier than did the formation s land between glaciations and after the last one. which they came to characterize . Even if we It was during these cold glacial periods that taiga discount for a moment the possibilities of con- reached its southernmost distribution . Indeed, tinuity of aridity through the warm and mois t fossils of Abies balsamea, Picea glauca, Larix phase of the Cenozoic Era, we can make obser- laricina, and Finns banksiana have been found vations in modern mesophytic regions that revea l across the region from South Carolina to Louisi- a mode of persistence which could have carrie d ana to Texas. xerophytes through moist cycles in the past . In practically all moist regions there are rocky mon- Xerophytic vegetatio n adnocks, exposed brows of slopes along valleys , Arid climates, as we know them, apparently epiphytic habitats, dunes, and evanescent bar e could not have existed to any great extent on th e areas resulting from the destruction of vegeta- North American continent in late Eocene time tion, all of which harbor xerophytic species . It

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Morning Session DAUBENMIRE-NORTH AMERICAN PLANT FORMATIONS 2 1 is to be noted that today in the wet climate o f and Central AmeriIt appears that this grou p Florida there are habitats suitable for the exist- of pines has been the stock from which the defi- ence of more than a third as many terrestrial suc- nitely xerophytic Pinus ponderosa and its allies culent cacti as are found in Arizona. Further- have arisen. Possibly the xerophytic ecotypes o f re, a fossil cactus of Eocene Age has been Pseudotsuga (i .e., ecotypes now included in P. found in the same deposit with such mesophyte s taxi f olia var. glauca) were late additions to th e as Liquidambar and Sabalites. xerophytic forest formation that were derived It seems fairly certain the deformations early from an ancestral species in the temperate meso- in the Cascadian Revolution produced topography phytic forest, for the species is not particularly that allowed a large dry area to develop in centra l southerly in its affinities, yet the trees of the in- Mexico. This was the first point of assembly terior are strongly related in an ecologic sens e for those xerophytic formations that were later to those forests that grow on dry soils . to spread northward in successive waves. Fos- The modern chaparral formation of Nort h sils of grazing animals in Miocene deposits that America had an origin and history similar t o are scattered from Oregon to Nebraska bear in- that of the xerophytic forest (Axelrod, 1939) . direct but indisputable evidence that much vegeta- Most of the dominants of this group were ever- tion at least as xerophytic in character as ope n green and adapted to the Mediterranean type o f forest had come into existence by Miocene time , climate that in early Cenozoic was probably thereby indicating significant uplifts in the Cor- found only in the Mexican interior, but later dillera as far back as early Oligocene . When the shifted area land became confined to that part Sierra Nevada was uplifted later in the Cenozoic, of the coast centering about southern California. the area occupied by xerophytic vegetation wa s Fossils identified as Arbutus, Castanopsis, and further enlarged . Umbellularia from Miocene deposits in Idaho Undoubtedly the first group of dominants to suggest that a heterogeneous assemblage includ- invade' these dry lands was joined by recruits ing those woody plants adapted to the Mediter- from time to time as a result of mutations in th e ranean type of climate first expanded northward surrounding mesophytic floras that produced spe- along the intermountain trough . Later, when th e cies pre-adapted to the dry area, thus aiding i n Sierra Nevada was uplifted to approximately its the regional differentiation of the xerophyti c present height, the Mediterranean elements were vegetation . eliminated to the leeward of this range and th e Since xerophytic formations could arise onl y residual scrub left in the interior became an im- as moist climate metamorphosed to dry, it might poverished zone composed mainly of deciduous Ukff the xerophytic forest dom - species fringing the foothills. This hypothesis i s Frtmvitk cembroides, substantiated by the fact that today there is a and Juniperus, was the first xerophytic formation decided blending of the continental and Mediter- to attain a wide distribution. Increasing aridit y ranean elements south of the zone of influenc e allowed this formation of open forests and wood- of the Sierras, that is, in Arizona !Ind Mexico . lands to emerge from the Mexican interior, and The desert formation was the third member at the same time, allowed the development of a of the xerophytic vegetation to emerge from Mex- slightly more xerophytic type of vegetation in it s ico and extend northward. Fossil evidence indi- original area . By Miocene time Pseudotsuga, cates that desert vegetation had reached the lati- Pinus, Cercocarpus, and Arbutus had displaced tude of southern California by mid-Miocene, an d the temperate mesophytic forest dominated b y by the end of that epoch had spread northward Sequoia as far north as central Idaho. Even- across the Great Basin . The ultimate extension tually the xerophytic forest extended a short wa y of the sagebrush-grass semidesert as a narro w into Canada on either side of the Rockies, and tongue up into British Columbia may have taken became differentiated into well-defined associa- place at equally as early date . tions that were arranged in a sequence of alti- Whereas both fossil evidence and the distri- tudinal zones and limited to either the oceani c butional patterns of modern species point to Mex- or the continental phase of the dry climates . In North America the zone of transition be- ico as the primary source of woody xerophyti c tween tropical and temperate mesophytic forest s vegetation, this is not equally true of the grass - is characterized by "hard pines," both in the re- lands. Floristic studies of the Palouse sugges t gion centering about northern Florida and at that the principal dominants of this vegetation intermediate altitudes in the mountains of Mexico grassland are indigenous to their present area,

BIOGEOGRAPHY Luncheon Session

presumably differentiating out as northerly ari d be • e+l -IrflxeTi origin. The Andropogons could regions developed-which were unsuited to the eco- easily have been extracted from seral vegetatio n logic requirements of and therefore not subject in the temperate mesophytic forest, such as th e to conquest by southerly xerophytes . Patterns o f modern broom-sedge community of abandoned modern species distribution indicate that thes e fields. On the other hand, the few Bouteloua s grasslands have drawn only a few subordinate s of these grasslands were undoubtedly drawn fro m from remote regions ; on the whole, the dominants the rich Bouteloua flora of the Mexican region. are essentially endemic to the northern intermoun- The Bouteloua element may well represent a rela- tain area. tively late invasion of midcontinental plains tha t At the other extreme, floristics strongly sug- had evolved in isolation from late Oligocetre tim e gest that the grasslands of the southern Rockie s until xerophytic vegetation from the 1 e.i€an' are Mexican in derivation, like the woody xero- center spread sufficiently that the two fiovas canine phytes. Grasslands east of the Rockies seem to in contact.

THE PHYTOGEOGRAPHY OF TH E NORTHWESTERN STATE S MORTON E. PEC K

The makeup of the present plant population The two great changes above mentioned carne of any area is the result not only of present con- on, of course, very slowly. The upward foul s ditions of climate, soil, etc., but to an even greater marking the course of the Cascade eleeat-€ : i-- extent of past geographical and climatic changes . itiated the period of volcanic activity .in tl .i .sic The effect of such a series of past changes an d tion. The- eruptions that occurred wore . M y their bearing on the plant distribution of toda y explosive, and numerous craters were , ea lhtldy' is well illustrated by a comparative study of th e built into lofty peOlO. -with extensive lava flows , : -• northwestern states in relation to that of sur- on their flanks and filling the intervals bet, veen : j rounding regions . This activity continued periodically for a ver y Except in the matter of soil composition , long time ; in a few places it has barely ceased . which must be omitted from our present consid- The more quiet lava flows to the eastward hav e eration, we need not go back of Tertiary time i n a similar history . In many places sheet -afte r our examination of these past factors of present sheet was laid down, often with long time .inter- distribution . The two most important events vals between. The final result was that a very bearing upon our problem-the vast volcani c large part of the original surfam . v_Vas buried activity that resulted largely in the erection o f beneath volcanic deposit . the Cascade barrier together with the repeate d The slow lowering of the general tempera- lava inundations to the eastward, and the genera l ture was sufficient to complete the almost *al lowering of the temperature associated with the elimination of the older flora, except, perhat, Quaternary ice invasion to the northward-mus t the southern part of our territory. While a have permanently displaced or exterminated th e tively .mall part of the two states was actually flora of an earlier age . glaciated, subarctic conditions must have prevailed , Before these events occurred there must hav e especially inland, as far south as central Oregon been a comparative uniformity of climatic con- and in the Cascades much farther. ditions, except in a few localities, over the whole In this gradual climatic change, this invasion of Washington and Oregon, that is, of such area s of a region of hitherto mild temperature and_ - as were above the sea ; for the western part of abundant moisture by conditions we now asso- the region was subject to elevations and depres- ciate with arctic or near arctic latitudes, we ar e sions from time to time that considerably in - to look for the advent of much orf our pr•eont creased or decreased the land area . Furthermore, flora, particularly that portion of it west-of the the climate, for at least a long period, had been Cascade divide. East of the Cascades other fac- much milder than it has ever been since and with tors have entered largely into • the detrmi,notioza- - abundant precipitation . of its present composition .

Luncheon Session PECK-PHYTOGEOGRAPHY OF THE NORTHWESTERN STATES 23 The approximation of the two great norther n mountain boundaries. Even the great majority land masses of the globe, Eurasian and North- of native shrubs and herbaceous species are no t ern American, along and near the arctic circle , identical with or closely related to Old World has resulted in a relatively uniform and stabl e forms . This seems to indicate that most of thes e plant population throughout this portion of both were not derived from the great circumpola r the Old World and the New. This circumpolar stock as a result of the last glacial invasion, but flora is probably a relatively old flora. It is no t from a more southerly source . likely that at any time in the past, unless at a ver y With the plant population of the higher por- remote period, has there been an effectual barrier tions of the Cascade divide and of the Olympi c to plant emigration between the continents, henc e Mountains, the situation is quite different. Many the uniformity and hence also the stability ; for species now inhabiting the small and often iso- periodic invasions after long periods of isolation lated arctic and subarctic alpine areas are un- serve to upset stability and stimulate evolution . questionably of the circumpolar stock, identical There have, of course, been north-and-south fluc- with or closely related to Eurasian types . The tuations from time to time in accordance with number of such forms, of course, increases as w e slow climatic changes, but these too have been go northward and the areas sink to lower alti- uniform for the whole vast area and cannot fo r tudes, finally becoming continuous with the gen- the most part have greatly affected the general eral circumpolar region. The long-current ex - stability. planation of this distributional pattern is tha t The climatic change with which we are par- during the last glacial invasion these far norther n ticularly concerned in the study of our area is the species gradually moved southward, probably a t arctic invasion that took place mainly in the low altitudes, since the high summits must hav e Quaternary. Let us see how it must have affecte d been deeply mantled with perennial snow . But the plant life of the several sections of this region . finally, when the invasion had passed its pea k During the milder period preceding the ad- and the northward retreat began, segments o f vent of this last ice age the maritime and submari- many of the fugitive species from high latitudes time flora about the north Pacific was doubtles s clung to the skirts of perennial winter as it with- continuous from Asia to North America . With drew to the highest summits, where they survive the increasing cold many of the species, driven to the present time, islands of arctic life in a sea southward, were able, by their natural means o f of low-altitude vegetation . The explanation seem s dispersal, to keep far enough ahead of the ad- quite satisfactory, making due allowance for con- vancing low temperature to maintain themselve s siderable evolutionary changes in the stock an d and survive, while perhaps the former plant popu- the gradual adjustment of many vigorous specie s lation disappeared as they advanced . The same of lower altitudes to the severe conditions of a n migration must have occurred on both sides o f alpine environment. the Pacific, since today we find many species now The case of the higher Blue Mountains, es- found on both the Asiatic and North America n pecially the Wallowa group, is quite similar . shores with a discontinuous distribution to th e Here, however, the factors determining the plan t northward. But in the meantime evolution had population seem more complex. In their geo- air=+ ceased, for in the case of some species th e logical history these mountains are closely allie d ,o segments have come to differ from each to the Rocky Mountain system . While, as might tier subspecifically or split into barely definabl e be expected, many of the plant species are iden- 'species . tical with those of the Cascades, many others ap- Inland as far eastward as the Cascade divid e parently came directly from the circumpola r we encounter the same phenomena, though only stock and have not become established in th e to a limited extent, and this mainly as to herb- Cascades. Still many others have come in by aceous and shrubby species. The species com- way of the Rocky Mountains, an older region , prising the great coniferous forests of the Pa- where they have undergone extensive evolu- cific slope are quite distinct from those on th e tionary changes since breaking with their more Asiatic side. It seems improbable these or any northerly forebears . Many of these are quite but their early forebears ever did form a part of identical with the Rocky Mountain species whil e the general circumpolar vegetation . There has others are more or less distinct. Since the in- doubtless been extensive north-and-south migra- terval separating the Wallowas from the Rocky tion due to fluctuations of climate, but mainly Mountains is rather narrow, species have prob- within the confines of relatively fixed ocean and ably arrived from time to time. The extent to

24 BIOGEOGRAPHY Luncheon Session _ which they differ from their Rocky Mountain tation. On higher slopes the flora is more like congeners may be taken as an indication of th e that of the section to the northward. Over nearly relative remoteness of the period of their estab- all this territory except the very alkaline and very lishment here . There is also a rather high per- sandy areas there is an almost continuous mantle centage of endemism among Wallowa species . of sagebrush, often very dwarf . The shallo w This is what we might expect from the uniqu e lakes and borders of the deeper lakes support a soil conditions and their relative isolation . dense growth of tules and other sedges . Most of the remaining portions of Washing - Often included in the Great Basin area, but ton and Oregon lying east of the Cascades are a t with certain strongly marked characteristics, i s moderate altitudes and seem to have receive d the drainage basin of the Owyhee River in east - their present plant population from the south- ern Malheur County . Over a large part of thi s ' ward, since it shows no very strong affinity with area Eocene clays predominate with lavas in les s the circumpolar flora. In a broad sense thi s abundance . Here the flora is largely that o f whole territory constitutes a northward extensio n southwestern Idaho and the adjoining portion o f of the Great Basin region. In a more restricte d Nevada and includes numerous species not oc- and perhaps more accurate sense the term Great . curring elsewhere in Oregon . Basin applies only to our territory south of th e Wholly or partly included within the Great Columbia drainage area, which is roughly the Basin territory are several small mountain groups , southern half of Oregon' east of the Cascades . such as the Steens and Trout Creek Mountain s The line separating the - two sections is very and two or three of southern Lake County, pre- vague and each is capable of further subdivision . senting floral characteristics of considerable in- The northern area is forest-fringed, but con- terest, but spare will not permit their discussion . sists largely of plains and hills originally mantle d We still have to consider briefly certain floral with grass, especially to the northward, and wit h features of southwestern Oregon . The question sagebrush and its common 'associates toward th e as to the source of the present plant population o f south. The soil, as previously implied, is mainl y this area, so far as our treatment is concerned , of volcanic .origin with extensive lava exposures , is less complex than that of some other sections . particularly to the southward, and deep deposit s A high percentage of the species of the Ump- of fine material toward the north., with extensive qua Valley are identical with those of the Wil- sand deposits along the Columbia river. The low lamette Valley, but there are many others which precipitation, annual extremes of temperature and here reach their northern limit with their mai n volcanic nature of the soil determine the char- distributional range to the southward . How muc h acter of the vegetation . The southern section southward migration of species from this are a has a more varied flora and more abundant spe- there may have been during the last glacial in- cies, among which both shrubby and herbaceous vasion we can only surmise, but it may well b e Compositae and the genera Astragalus and Erio- that many of the hardier forms were able to sur- gonum predominate. - vive the lower temperature, and with the retur n The territory of the Great Basin area in th e of a milder climate pushed northward in part into more restricted sense is for the most part a regio n the Willamette Valley, while the less resistant , of imperfect drainage with numerous extensiv e that had been driven southward, surged back into dry lake beds and many shallow lakes now greatl y the Umpqua Valley. Such movements woul d shrunken and gradually disappearing . The soil have resulted in the free mingling of species o f of the lake beds and that about the existing lake s northern and southern relationships as we find is more or less strongly alkaline and consist s today. largely of heavy clay ; both conditions exist be - The Rogue River Valley, set off from the cause of decomposition of volcanic material to- Umpqua by only a low divide, has a far higher gether with the lack of drainage . In some places percentage of species whose principal range is to there are large sandy desert areas with extensiv e the southward. This area may have been suf- dunes . ficiently removed from the glacial conditions fa r In and adjoining the lake-floor area we mee t to the northward so that its species populatio n with the most characteristic Great Basin flora . was not profoundly distributed by the lower Shrubby and herbaceous Chenopodiaceae together temperature, though of this we have no direc t with salt grass Distichlis are dominant, while evidence. at slightly higher elevations there is a varie d Whatever climatic changes bhe,re- may, iav though still characteristically Great Basin vege - been in this region during tae Quater.nark:, apa _ •l.- .

whatever their effects may have been on the vege- of the foreigners are, of course, from western tation, the flora of the Siskiyou and souther n Europe, the two regions being so similar in cli- Coast Mountains bears strong evidence of a rela- mate. In the Umpqua and Rogue valleys particu- tive geographical fixity through a long period o f larly there is a considerable proportion of Medi- time ; if so we may interpret a remarkably high terranean species . East of the Cascades certai n percentage of endemism with many very distinc t Old World weedy grasses and Cruciferae are ex- species and at least two strongly marked endemi c genera. cessively , abundant over large areas. Add to A word may he added as to exotics in ou r these immigrations the effects on the native flora area. Over nearly all cultivated sections of Wash- of cultivation, deforestation and overpasturage by ington and Oregon west of the Cascade Moun- domestic animals, and we realize what profoun d taius:.foreign species have._ ' largely displaced changes have taken place and are still taking plac e We have almost "weeds." Most through human agency.

THEE ORIGIN AND DISTRIBUTION OF LIVIN G NORTH AMERICAN MAMMAL S

KENNETH L . GORDO N

Let us imagine for the moment that we are When we leave this northern forest and trave l travelers from Europe, familiar with the animal through the eastern United States in an area life of northern Europe and of Siberia and tha t once covered by an extensive forest of deciduou s we are starting on the Arctic tundras for our trees we still find at first a good many familiar trip through North America . forms. Among these are weasels and otters, th e Here on these barren wastes we would fin d lynx, and farther south the bobcat, the red fo x mammals very similar to those of the Old Worl d and bears. Some of the moles and shrews, the tundras, the lemmings, the Arctic hare, the ermine meadow mice and pine mice, the marmot an d or weasel, the wolf, the Arctic fox, the barre n the squirrels are obviously similar to forms a t ground caribou which is the counterpart of th e home. But as we go southward, and especiall y reindeer, and the musk ox . The last would b e when we get into the pine forests and bottomlan d a new form, although in former times it wa s woods of the southern -coastal plain, we see man y found on the Asiatic tundra . The whales an d mammals that are new to us . The muskrat w e seals of the Arctic seas would be much the same . know as a widely introduced and not alway s As we pass from the tundra through the bel t welcome form. Many rodents, such as white - of more or less scattered, stunted trees into th e footed mice, wood rats, cotton. rats, rice rats, and far stretching coniferous forest we find the sam e harvest mice, and the cottontail rabbits are a little combinations of pine and fir and spruce, of birch strange. The white-tailed deer has no counter - and willow and poplar that characterize the north - part at home. We make an acquaintance for the ern forest or taiga of Eurasia . And we find a first time with a variety of predatory forms, es- great many familiar mammals, although some o f pecially the raccoon and some odd black and whit e them have different names . The woodland cari- animals that we are not sure we care to meet bou is like the forest type of reindeer . The moose again. Perhaps strangest of all is that survivo r is the same hulking creature as the Old Worl d out of a remote geological past, the Virgini a elk, and later in the western mountains we will opossum. find that the so-called elk is similar to the Euro- We cross the Mississippi River and trave l pean stag. We find many well known predator y widely through the far stretching arid lands o f mammals, bears, wolves, lynxes, martens or sa- the west with their vegetative cover of grass , bles, weasels, wolverines and otters and althoug h sagebrush and other shrubs, and of desert plants. we see much less of the rodents and other smaller And just as we did in the deciduous forest area mammals we find that for the most part they we find that familiar mammals are more common seem quite similar to our Old World forms, es- in the northern parts of these arid lands . The pecially the beaver and some of the wolves . bison that once roamed the plains is not greatly

26 BIOGEOGRAPHY Afternoon Session different from the once common European wisent . ing the jaguar and ocelot . There are few un- Wolves and bears, some of the weasels, otters , gulates or hoofed mammals, but we do find tapirs, and meadow mice are familiar. Ground squirrels peccaries, and small deer or brockets . are found in northern Asia and eastern Europ e As we leave Panama and look back on ou r but in no such variety as they are in America . travels through North America, we review the But we find, and especially as we go south - main features of the distribution of mammals . ward into the desert areas, a large number o f The mammals of the tundra, of the great Canadia n mammals that are unfamiliar to us, an eve n forest and the forests of the high western moun- larger number than we found in the easter n tains were very familiar to the eye of a Euro- United States. Some of these we saw for th e pean. To the southward in the deciduous for- first time east of the Mississippi River, the white - ests we began to meet many unfamiliar forms, footed mice, wood rats, and harvest mice, the rac- and in the arid western lands we found many coon and the skunks. Entirely new to us ar e more. In the tropical forests we found mammal s some mammals that have no close relatives out - unlike those farther north but similar to those o f side of North America, the pronghorn antelope , South America. In short, we found a threefold the pocket gophers, the pocket mice and kangaro o division of North America : a boreal or northern rats . The jackrabbits are obviously hares, but part bearing a close relationship to the northern ours cannot match their size and speed . We add parts of Europe and Asia, an austral or southern to our list of new forms the prairie dog, grass - part in which the relationship to the Old Worl d hopper mouse, badger, black-footed ferret, deser t is more remote and in which there have devel- and kit foxes, and in the far West the ring-tail , oped many distinctively North American mam- which we learn is a relative of the raccoon . mals, and finally a tropical section which is obvi- In the woodlands of juniper and pinon pin e ously closely related to South America in its and in the open forests of yellow pine that clothe mammalian fauna . the lower slopes of the western cordilleras, man y The various divisions of the present Nort h of these lowland forms persist and mingle with American fauna are the results of a long geo- a truly forest fauna. When we climb into th e logical history and cannot be adequately explaine d denser growths of fir and spruce, pine and aspen unless we keep that history in mind . By way o f at the higher altitudes we find a forest with its as- review I should like to refer briefly to some o f sociated fauna that is similar to the northern an d the past events, discussed in preceding talks, that mountain forests of the Old World . Elk and are of particular importance in understandin g mountain sheep, conies, marmots, chipmunks , the present distribution of mammals in North red-backed mice, marten, wolverine, bears, wolve s America. and lynx are similar to the Old World types . Beginning in the Miocene epoch there wa s In the high and dry interior of Mexico we rrenewed mountain making activity that continued find an arid land flora and fauna. If we go into through the Pliocene and Pleistocene epochs an d the high mountains we enter a temperate zon e resulted in the re-elevation of the Rocky Moun- forest resembling a good deal the mountain for- tains, the formation of the Sierra Nevadas an d ests of the western states. Cascades, and later of the Coast Ranges . As a But when we drop down the southern slope s consequence there was a cooling of continenta l of these mountains into the lowlands of Centra l temperatures that culminated in the Ice Age o f America, we find in the tropical forests and savan- the Pleistocene epoch, and an increasing aridity , nas mammals that are almost completely unfa- especially in the rain shadows of the rising ranges . miliar to us . There is a considerable variety o f The tropical and subtropical forests of th e opossums. Many species of bats are present . early Tertiary retreated southward and were re- Monkeys roam the jungle ; and among the oddest placed across much of the present United State s mammals that we find are sloths, anteaters, and by a temperate deciduous forest. This forest in armadillos. There are rodents of genera and eve n turn, caught between the advancing boreal fores t of families that are confined to Central and Sout h to the north and the expanding grasslands an d America. There are many carnivores, but mostly deserts to the south, finally broke up and becam e they are kinds that we did not find farther north. restricted to the eastern states, with some relic Among them are the bush clog, not only the rac- forms lingering on the west coast where they coon but its relatives the kinkajou and the coat i mingled with advancing boreal plants . As a final mundi, weasels and some of their relatives, hog- result of these changes there became establishe d nosed skunks, otters, and a number of cats includ - the major vegetation types as we know them to-

Afternoon Session GORDON-LIVING NORTH AMERICAN MAMMALS 27 day, the tropical and subtropical forests of Cen- footed mice and woodrats), tropical types of the tral America and the lowlands of Mexico, the dog family, ocelot, jaguar, coati mundis and other grasslands and deserts of the arid West, the de- relatives of the raccoon, peccaries, the America n ciduous forest of the eastern states, the conifer- tapir, and some of the New World deer . When ous forest of Canada and the western mountains , the Pliocene land bridge was established wit h and the tundra of the far north. South America, this element poured across it t o There were intermittent land connections with such an extent that it forms a large and importan t Asia across Bering Sea through the Tertiar y part of the present fauna of South America . period. These were particularly well establishe d in the Pliocene and Pleistocene epochs, permittin g Austral North American element the free interchange of mammals between the This element is composed of forms that hav e northern lands . On the other hand, the South developed in the temperate central part of th e American fauna had developed in splendid isola- continent. This development, however, has oc- tion since the earliest Tertiary . During the Plio- curred in two quite diverse situations p h . One grou cene a connection was established with Nort was associated with the deciduous forest onc e America and a two way traffic began that flooded widespread across the continent but now confine d the southern continent with northern mammal s to the eastern states, the other group with th e and carried many South American forms widel y arid grasslands and deserts that began to sprea d over North America, although very few of these rapidly in the Miocene epoch . The forest group now remain north of the tropical areas . includes certain shrews and the eastern mole, th e In the light of this past history we find that eastern chipmunk, gray and fox squirrels . The the present mammalian fauna of North America grassland and desert group includes some of th e has had various origins. Our knowledge of the most distinctive of North American mammals, geological history of many forms is so scanty ground squirrels (Citellus), prairie .dog, pocket that we can assign their origins only tentatively. mice, kangaroo rats and mice, grasshopper mouse , South American element badger, and pronghorn antelope. Other austral l These are the mammals developed during the forms are more wide ranging, such as cottontai long isolation of South America, and include ar- rabbits, gophers, harvest mouse, white-footed r madillos, anteaters, and monkeys ; a large grou p mouse, gray fox, raccoon, skunks, and dee of rodents, the histricomorphs, which includes (Odocoileus) . capybaras, spiny rats, cavies (with the guinea pi g as an example), and porcupines ; and possibly the Boreal American element various opossums . For the most part this element This element is composed of mammals evolve d is confined to the tropical sections of central in the colder northern lands and now in the mai n America and Mexico . The armadillo is common associated with the boreal coniferous forest . in Texas. The Virginia opossum is widespread Many of the genera are panboreal in distribution , throughout the deciduous forest area . Only the that is, they are found in the northern parts o f porcupine has retained an extensive northern both the Old and the New World, and they hav e range, where it is found through most of th e a nearly equal geological record in both areas . coniferous forest areas . Could we know more of their past history w e would probably assign many of them definitely Tropical North American elemen t to an Old World origin . This panboreal grou p This element is composed in part of the de- includes hares, beavers, lemmings, red-backe d scendants of ancient types found in America i n mouse, pine mouse, meadow mouse, weasels , the mid-Tertiary and that apparently retreated wolves, arctic and red foxes . Other genera are southward with the tropical and sub-tropical for- known at present only from the New World, bu t est, in part of later immigrants from the north or in the main are closely allied to Old World forms . from the Old World that found conditions in the Included here are pigmy shrews, shrew moles , tropical areas particularly favorable. These trop- Brewer's mole, western moles, pine squirrel, fly- ical areas formed one of the most distinctive cen- ing squirrels, and lemming mice (Synaptomys) . ters of evolution in North America . In this ele- A few genera may have had their origin in North ment are included several tree squirrels, a great America, and later crossed over into the Old variety of native rats and mice of the subfamily World, such as the chipmunk (Eutamias), mar- Cricetinae (forms allied to our common white- mots, and jumping mouse (Zapus) .

% E F, - . :1fL 9-■ I L . y~ . li4 f- -I ter . . . 1 - r t. n el .r- _ 71 I III 1 ■_ ■ ■ 28 _ Y BIOGEOGRAPHY - - - I Afternoon Session ■. L Old World Elemen t tropical and subtropical forest of Central Americ a r Many Old World forms came across the Ber- and the lowlands of Mexico . This fauna is pri- ing bridge in Pleistocene times ; they are largely marily of tropical North American and South found in the northern forest and tundra. This American origin with a strong infusion of aus- element includes the cony (Ochotona), bears, tral genera and but few from Boreal America and marten, wolverine, lynx, elk (Cervus), moose the Old World . The austral faunas are char- . int.. acteristic of the temperate midsections of the ■ caribou, bison, mountain sheep, mountai n goat and musk-ox. continent. About fifty per cent of the genera ar e It is interesting to follow the changing com- of southern origin, mainly austral American with position in local lists made in various parts of th e a very small percentage of tropical North Ameri- ■ continent. Lists of mammals from the arctic can and South American genera . The borea l faunas are characteristic of the colder northern _1 tundra are made up almost entirely of Old Worl d a or Boreal genera. As we come southward through parts of the continent and the genera are predomi - the Canadian forest the lists show a gradual addi- nantly boreal or Old World in origin . I I tion of austral genera . The first sharp break The austral faunas can be divided into two ■Y comes at the contact between the coniferous forest groups. One is characteristic of the deciduous . .and the short-grass plains or with the sagebrush forest areas of the eastern states, and is here and bunchgrass lands of the Northwest . South- called the deciduan fauna . The other inhabits the I ward of this contact the generic composition of arid grasslands and deserts of the West and i s n the local lists abruptly changes to a predominanc e here called the sonoran fauna. of austral forms . This change is more gradual Likewise the boreal faunas can be divided across the contact between the coniferous and into two assemblages . One is characteristic of the deciduous forests, and also in the montan e the far flung coniferous forest of Canada, Alaska , forests of the lower slopes of the western moun- and the western mountains. We may call this tains. Another sharp break occurs where th e the coniferan fauna. The other group, the tun- highlands of Mexico break down into the tropi- dran fauna, dwells on the treeless tundras of th e cal lowlands. In these tropical lands the local Arctic regions. lists are dominated by genera of tropical Nort h In tabular form these faunas may be show n American or South American origin. as follows : It is also interesting to note that no mammal Tropical North American fauna Austral fauna s of South American origin has been able to cros s Deciduan fauna the intervening temperate and cold lands to enter Sonoran faun a the Old World by way of the Bering Strait lan d Boreal faunas bridge. Only one of the many invaders of South Coniferan fauna American origin, the porcupine, has been able to Tundran fauna ■ retain a wide distribution in the northern conti - Before going on to a description of the Nort h nent. On the other hand many Old World an d American faunas it might be well to define cer- • ■ _ North American mammals have penetrated Sout h tain terms that are used in this paper. A fauna America, so much so that about half of the genera is an assemblage of animals that commonly occu r " ■ -1 now found there are of northern origin . together and that occupy a distinctive habitat o r Most of the generl, that have a wide range i n range. Some members of the fauna will be lim- the New World are of Old World or Borea l ited to only a part of the habitat or range, an d ..origin, notably Canis (wolves), Fells (cats), Ur- some of the more adaptable members will extend R' su.c (bears), weasels (,>I9ustela), common shrews their distribution into the ranges of adjacent ` (Corex) . the beaver, and the meadow mice (Mi- faunas. A faunal area is a region of variable , - crotuc): . Few austral or tropical genera hav e size, occupied primarily by a characteristic fauna , I achieved an equal range in North America . The but into which the more adaptable members o f ▪ white-footed mouse (Peromvscus) has the widest other faunas may extend. The two terms, fauna range of any austral form . and faunal area, are confusingly alike, but the The mammals of North America can be di- first lays its emphasis on a mobile assemblage of vided into a number of faunal groups that are animals that has adapted itself to a particular se t • closely associated with the main vegetation types of conditions, and is constantly changing in it s that have been mentioned earlier . There is in the adjustment to new conditions. The second ter m ▪ first place a threefold division . The tropical places its emphasis on a certain geographical area Iti North American fauna is characteristic of the with its characteristic physical and biotic cond

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Afternoon Session GORDON-LIVING NORTH AMERICAN MAMMALS tions, and the way in which that area comes to be TROPICAL NORTH AMERICAN FAUNA . inhabited by animals that in part originate within Extent it and in part enter it from various sources of a This fauna, as mentioned before, occupies-• the origin. For example the sonoran fauna is tropical and subtropical forests of Central Amer- group of animals that are adapted for life in arid ica and the lowlands of Mexico . and semiarid lands. It includes such mammals a s On Barro Colorado Island in Panama 60 pe r kangaroo rats, pocket mice, kangaroo mice, prairie cent of the genera are of South American origin , dogs, badgers, skunks, and many others . Of y 30 per cent of tropical North American origin , these, the kangaroo rats and pocket mice occup and the remainder of austral or Old . World practically the whole faunal range . he kangaroo ' mice and prairie doge are more limited in their origin. Going northward there is an increasing distribution, the first being found in the Great number of austral and northern genera _ Basin, and the second largely on the Great Plains . South American elemen t The badger, although most abundant in the fauna l This element is represented by several genera - range, is sufficiently .laptable to extend its own of opossums (which possibly should be consid- range somewhat into adjacent areas . The skunks ered of tropical North American origin), mon- are even more adaptable and range so widely that keys, armadillos, ant eaters, and several genera o f they are perhaps as characteristic of the decidua n histricomorph rodents, such as the capybara, as of the sonoran fauna. The sonoran fauna l spiny rats and South American porcupine . area consists of the arid lands of the West . It is occupied primarily by the sonoran fauna, But -Tropical North American elemen t in places where the local habitat permits- it i iin- This element includes certain tree squirrels, vaded by members of adjacent faunas . And in nearly a dozen genera of mice or rats of the sub - certain sections it may be inhabited by relic forms family Cricetinae (which also includes the fa- from an earlier fauna that has retreated wit h miliar white-footed mice and woodrats of more. changing conditions and has left these forlor n northern areas), several cats (such as • jiaguar, rearguards behind, as where some of the isolated ocelot and eyra), the bush dog, such relatives o f western mountains rise above arid lowlands an d the raccoon as coatis and kinkajou, the hog-nose d on their upper slopes still yield a refuge for skunk, the grison, peccaries and tapir. northern plants and animals which during the ice ages spread over much of the area . Austral elemen t An area of faunal origin is a portion ' of the The short-tailed shrew of the genus Crypto- earth's surface sufficiently distinctive in its physi- tis has passed on into northern South America t o cal and climatic characteristics and sufficiently iso- attain the distinction of being the only insectivore lated from other areas to serve as a center o f now found in that continent . Also represented evolution for new forms of life . Animals de- are species or subspecies of cottontail rabbits • rived from these areas are spoken of,das faunal (genus Sylvilagus), white-footed :mice, woodrats , elements. In this paper only the major areas o f gophers, the raccoon, and the gray fox . faunal origin are considered. Each could be broken down into smaller differentiation areas i f Boreal and Old World elements given a more detailed consideration . These elements are represented by weasels, It is unfortunate that some very convenien t the coyote, and otter . terms have been used in all three of these senses . For example the term boreal may be applied t o the boreal faunal area of North America with it s SONORAN FAUNA col to cold-temperate climate .and its cover o f tundra or coniferous forest. It may designate the Extent boreal fauna of moose, reindeer, lynx, pine squir- This is the fauna of the arid nonforested sec- rel, varying hare, beaver, and many other mam- tions of the continent from the tableland of Mex- mals which are characteristic of the boreal area, ico and Lower California north to south central but some of which extend well beyond i. where Canada and eastern Washington . It occupies a I. habitats are suitable. And the term is used in con- number of vegetation types, particularly the grass - nection with the cold temperate part or zone o f lands, sagebrush and' desert, also in somewhat re- North America which has served as a minor cen - duced number.* the chaparral and juniper-pino n . ter of evolution for mammals which for the mos t pine woodlands . Usually 50 to 60 per cent of th e part had their.' ultimate origin in the Old World . genera are of austral North American origin .

Restricted Austral elements Restricted Austral element Some of the most characteristic mammals o f A considerable number of genera or species; North America are members of the sonoran are confined -at the present time to this fauna, and fauna and extend little if at all beyond the area s seldom range beyond the limits of the main faunal occupied by it . Among these are the Crawford 's areas. Among these are the short-tailed shre w shrew of the desert areas ; the pygmy rabbit (Syl- (Blarna), the eastern chipmunk, the gray and fo x vilagus idahoensis) of the sagebrush country ; the squirrels, the southern flying squirrel," the marsfl majority of the species of ground squirrels ; the and swamp rabbits, and the round-tailed muskrat. prairie dog of the plains ; the widespread pocket mice and kangaroo rats ; the kangaroo mouse o f Wide ranging Austral forms the Great Basin section ; the grasshopper mouse ; Gray foxes, striped and spotted skunks are the badger ; and the pronghorn antelope. common members of this fauna, but range far beyond its limits. The same is true of the white - Widespread Austral forms footed mice, and of cottontail rabbits . Some austral 'genera found in the sonoran fauna are widely distributed and are character- Tropical North American elemen t istically found in the southern half of the conti- This element is best represented on the south- nent, but are not confined to either of the austra l ern coastal plain, and includes the Virginia opos- faunas . The cottontail rabbits, deer mice, gray sum, the cotton and rice rats. fox, raccoon, striped and spotted skunks, and th e deer of the genus Odocoileus belong in this group . Boreal elemen t Of this element the pine mouse is the most Tropical North American elemen t widely distributed within the deciduous forest -A few of the tropical genera or species hav e area and the most nearly confined to it. Star- extended their range sufficiently far north to en - nosed mole, marmot, jumping mice and beave r ter some of the desert habitats . Among these are are. lacking in the deep South, become more abun- the cotton rat, the coati mundi (a relative of th e dant toward the no-rth, and for the most part, are raccoon), the hog-nosed skunk, and the peccary . wide ranging members in the boreal faunas . Boreal element - Old World element This element, as might be expected, is better The common shrews (Sorex), otter, lynx bob- represented in the northern plains and sagebrush cat and moose are of Old World origin ., Of ,thes country than it is in the desert . Some of the the lynx and moose barely enter the nortl,ern,'pax t mammals of boreal origin or affinities are meado w of the deciduous forest . mice, sagebrush vole, muskrat and wolves . CONIFERAN FAUNA Old World elemen t This element consists mainly of larger forms Extent that have for the most part become extinct o r This fauna is characteristic of the conifer rare in the sonoran habitats, the grizzly bear, th e forest that stretches widely across Canada otter, the elk, and the bison. Alaska and extends in long peninsulas and islands 1 down the Alleghany mountains, the Rocky Moan= . tains, and the Cascada-Sierra-Nevada' rangO . ' " - DECIDUAN FAUN A Some of its members range rather extens ;iv4y' Extent into adjacent faunal areas, especially into- .'_the- . ,_ This fauna is found in the deciduous fores t tundra and into the northern part of the decide areas of the eastern United States . To the north , ous forest. In its most characteristic forrn it is i in the region of mixed hardwoods and conifers, it found in the Canadian forest, and, somewha mingles with the coniferan fauna. On the At- t diluted fashion extends down the high subalprile, f • lantic and Gulf coastal plain it occupies the south - forest of the western mountains . In the' tow, , . ern pine forest. This pine forest is considere d more open, sunnier and warmer forest areas and by Clements to be subclimax to the deciduous for - in the coastal forest it intermingles in consider - est ; it is, however, the home of an assemblage o f able degree with the austral fauna . In origin i t mammals that forms a distinctive subdivision o f is predominantly Old World and Boreal North the deciduan fauna . American.

Afternoon Session GORDON-LIVING NORTH AMERICAN MAMMALS 31 Old World element SUMMARY : NORTH AMERICAN FAUNA S Shrews (Sorex), marten, fisher, wolverine, otter, lynx, moose and caribou are widespread an d Faunas Associated vegetation Sources of origin characteristic forms . Boreal Tundran Tundra Old World, Panboreal Austral N. Amer. Boreal elemen t Coniferan Coniferous forest Old World, Panboreal, Boreal N. Amer. Aust. N. Amer., The pigmy shrew (Microsorex), pine squir- S . Amer. rel, northern flying squirrel, lemming mouse an d snowshoe rabbit are members of this fauna . Austral Deciduan Deciduous forest Austral N . Amer. Southern pine forest Panboreal, Boreal N . Amer. Austral element S. bottomland wood s Old World, Trop . N . Amer. Sonoran Grasslands Austral N . Amer. Some of the more wide ranging of the aus- Sagebrush Panboreal, Old World tral mammals become members of this fauna, Desert Boreal N. Amer., especially in the western mountains . These in- Trop. N. Amer. Trop. N . Amer. Rain forest, savanna S . Amer., Trop. N. clude the white-footed mouse, woodrat, raccoon , Amer. Austral N. Amer. striped skunk and badger. Old World, Panboreal

South American element Only one mammal of South American origin , CONCLUSION the porcupine, is a member of the coniferan fauna . What of the position of Oregon in regard t o these faunas? The tundran fauna is not repre- sented. The alpine tundras of the high peaks ar e TUNDRAN FAUNA invaded by various mammals from lower eleva- tions, but no true tundran mammal is present . Extent The mountain and forested area have a typi- This fauna occupies the tundra north of o r cal coniferan fauna . Detailed studies of these above the limit of tree growth in Alaska, northern forest areas reveal the presence of distinct sub - Canada, and on the islands north of the continent . divisions of this coniferan fauna, particularly in It is almost completely Old World and boreal regard to the coast forest of Douglas-fir and hem - American in origin ; only one austral genus has lock, the subalpine forest of the higher Cascades entered this fauna. and of the Blue Mountains, and the yellow pin e forest of eastern Oregon . Old World element The sagebrush, grasslands, and juniper wood - lands of eastern Oregon have a typical sonoran Definitely . Old World in origin are the pola r fauna which has its fullest development in th e bear, lemmings, caribou and musk-ox . southeastern section of the state . There is a strong invasion of austral or sonoran forms int o Boreal North American element the upper Rogue River Valley, represented b y In the tundran fauna this element is pan- antelope, black-tailed jackrabbit, western gray boreal and hence quite possibly of Old World squirrel, dusky-footed woodrat, Gambel 's and origin also . It is represented by the Arctic hare , Gilbert's white-footed mice, harvest mouse, kan- wolf, Arctic fox and Arctic weasel . garoo rat, gray fox, striped skunk, ring-tail (Bas- sariscus), and a number of other forms . There is a strong infusion of austral or sonoran forms Austral North American elemen t in the Willamette Valley. These include the Ground squirrels of the genus Citellus have black-tailed jackrabbit, western gray squirrel , entered the tundra in the region westward fro m gray digger, dusky-footed woodrat, gray fox , Hudson Bay. coyote, striped and spotted skunks, and raccoon .

PLEISTOCENE AND POSTGLACIAL CLIMAT E AND CHRONOLOG Y

IRA S . ALLISO N

TERMINOLOG Y during which glaciers were built up in Canada When geology as a science was in its infancy, and spread southward into the United States . the materials now referred to the Pleistocen e The principal centers of accumulation were i n were called "drift." They were ascribed (but n o the western Cordillera, the Keewatin area wes t doubt with some misgivings) to Noah's Flood of Hudson Bay, the Patrician area north of Lak e and hence they were assigned to a supposed Di- Superior, and on Laborador . After each major luvial Period . Later deposits were Alluvial . Af- advance the ice melted away, temperate climat e ter Louis Agassiz in 1837 was able to demonstrate plants and animals returned to the glaciated areas , the essential identity of origin of the so-calle d fossils were caught and preserved in peat bogs , "drift" on the plains of Germany with that o f the newly formed glacial deposits were weathere d the glacial deposits immediately below the pres- and eroded, and soil zones were formed-only to ent glaciers in the Alps, the still current hybrid be buried by the deposits of the glacier of th e term "glacial drift" came into common use fo r next succeeding stage . The substages of the all glacial deposits. last or Wisconsin stage, however, lack these in- The time terms Eocene, Miocene, and Plio- terstadial features and evidently were closely re- cene were introduced by Sir Charles Lyell . Pal- lated in time. eocene, Oligocene, Pleistocene (1839) and Re- A similar fourfold sequence has been estab- cent (1833) were added to the series later . lished in Europe and there too multiple morainic In modern usage the name Pleistocene, mean- systems are characteristic of the last stage . ing most recent, is synonymous with the Ice Age , the time of widespread continental glaciation, PLEISTOCENE CLIMATE S especially in North America and Europe . The Nebraskan and A f tonian time since the end of the Ice Age is considere d The climate of the Pleistocene encompasse s Postglacial, sometimes called Recent or Holocene. four glacial stages and three relatively mild inter- Inasmuch as considerable ice now covers Green - glacial stages . During the first glacial stage, the land and Antarctica, some geologists think tha t Nebraskan, an icesheet from the Keewatin cen- the Ice Age is still with us, and so they reject ter reached southward across eastern Nebraska, such terms as Recent and Postglacial as mean- northeastern Kansas, Minnesota and Iowa int o ingless. central Missouri . After the Nebraskan iceshee t melted away, its deposits, averaging about 10 0 STANDARD PLEISTOCENE SUCCESSIO N feet in thickness, lay exposed to the weather for a IN NORTH AMERIC A long time. Its morainal topography was subdue d The glacial stages and substages most gen- and it was dissected by stream erosion. Soils were erally accepted, together with the intervening in -. formed over its surface, claypans of sticky clay terglacial stages and associated deposits, are a s called gumbotil were developed to thicknesses o f follows : 6 to 8 feet in the subsoil in poorly drained areas , Recent or Postglacial and calcium carbonate was leached from the de- "Mankato-Valders drif t posits to depths of as much as 20 feet in the out- Cary drif t wash gravels. Pollen grains from peat bogs in Wisconsin Tazewell drift Iowa record first the return of spruce forests, Peorian loes s then the spread of grasses and oaks, and finally Iowan drift Pleistocene Sangamon (third) interglacial stage the reappearance of conifers . This plant succes- Illinoian drift sion denotes a change from cool moist condition s Yarmouth (second) interglacial stag e to a climate about as warm and dry as the presen t .Kansan drif t one in that area, followed by a return to a coo l Aftonian (first) interglacial stage moist climate that apparently heralded the ap- Nebraskan drif t proach of the Kansan icesheet which buried an d These superposed or overlapping deposits• in- preserved the fossil soils, gumbotil, tree stumps , dicate the occurrence of four main glacial stages and peat beds . The temperate climate of the Af-

32

Afternoon Session ALLISON-PLEISTOCENE AND POSTGLACIAL CLIMAT E tonian interglacial stage is supported also by fos- Whether a correlative ice sheet formed in the sils of horses, elephants, camels, bison, ground Keewatin area at the same time is not known. • - sloths, peccaries, deer, bears, and beavers, but th e In keeping with its lesser age, Illinoian drift i s exact stratigraphic source of many of these earl y liveathered much less than the Kansan and Ne- Pleistocene fossils is open to question . Perhaps braskan, but it is oxidized nevertheless to a dept h a number of these animals lived not far away of about 10 feet, is leached to about 8 feet, an d even during the boreal conditions of the glacial in wet areas has been converted to gumbotil 4 to stages . At any rate they were ready to invade 6 feet thick. As these weathered zones pass unde r the glaciated areas as soon as- the proper vegeta- Wisconsin drift with virtually undiminished thick- tion had been established, especially grasses for nesses, most of the weathering took place before the grazing horses, bison, and camels . Wisconsin time, hence during the third or Sanga- mon interglacial stage. Deglaciation in Sangamon Kansan and Yarmout h time probably was complete. Ice sheets of the Kansan glacial stage came Analysis of pollen from peat of Sangamon from both the Keewatin and Labradorian centers . age overlying Illinoian till in Iowa shows _a flora At its maximum extent Kansan ice from the Kee- of pine, spruce, hemlock, beech, oak, and rasses, watin center extended to northern Missouri an d which as a whole indicate a climatic amelioratio n overreached the Nebraskan deposits southwar d like that of Aftonian time, but no consistent cli- and westward, while that from the Labrador cen- matic trends are apparent in the few thin pea t ter extended southwestward to southern Illinois . sections described. The Don beds at Toronto , The Kansan till sheet thus deposited was orig- Canada, carry an extensive and varied flora, in- inally about 50 feet thick on the plains . It too has cluding the pawpaw and osage orange, which in- been deeply weathered. Iron-bearing mineral s dicate a climate warmer than the present . have been oxidized to a depth of 20 feet or more , Animal fossils of Sangamon age include snails calcium carbonate has been leached from the up- (of fresh-water, forest, and prairie habitats), permost 15 feet, and clayey gumbotil commonly 8 horses, elephants, camels, bison, deer, antelope-:. to 12 feet thick has been formed in wet areas . peccaries, weasels, rodents, etc. Most of that alteration took place during the long second or Yarmouth interglacial stage, becaus e Wiconsin : Iowan substage and Peorian loess sections of deeply decayed and leached Kansan The Iowan drift of early Wisconsin age is a till are found to underlie less deeply weathere d thin sheet of very bouldery till of Keewatin ori- Illinoian till. Buried soils, peat beds, and de- gin, that covers much of the northern half o f posits of windblown loess of Yarmouth age are Iowa and part of southeastern Minnesota. An common, but the associated fossils of plants an d area of drift in northern Montana, southwester , animals of Yarmouth age merely indicate a re - Saskatchewan, and southern Alberta is probably turn to climatic conditions much like the present . its correlative. Elsewhere Iowan drift underlies The fossil plants recorded by pollen in peat bog s a younger till sheet or has not been recognized. include tamarack, balsam fir, pine, and birch, sug- Boulders of granite are notably large an d gesting a somewhat cool climate . Fossil mammals common in the Iowan drift of Iowa where its include horses, elephants, Bison, deer, peccaries , average thickness is only about 10 feet . Unlike tapirs, ground sloths, wolves, beavers, skunks, an d the older drift sheets the Iowan is relatively un- hares. As tapirs and peccaries inhabit more weathered and little eroded . It is leached to an southerly areas today, the climate of part of Yar- average depth of about 5i feet but no gumboti l -L ` ootk time may have been warmer than the has formed on it. , k` present. The fresh, unweathered Iowan drift was im- mediately covered over wide areas by a mantle Illinoian and Sangamon of Peorian loess of eolian origin, generally abou t _ During the Illinoiaaor third glacial stage a 10 feet but locally as much as 100 feet thick. No _large ice sheet formed over the Labradorian cen - peat sections• and only a few logs of spruce, yew , ter, and spread southward over New Englan d and hemlock have been found on the. Iowan till, ~. L and southwestward .across most of Illinois, an d and the record of vertebrates in Peorian time i n even about 20 miles into southeastern Iowa nea r Iowa is limited to muskov, - elephant, and- bison. • Burlington. = In doing so it forced the Mississippi From the base of the loess in Nebraska, howevez; River into a new temporary course several miles where Iowan drift is lacking, has come a rich West of the present Iowa-Illinois boundary line . fauna of molluscs, mammoths, antelopes, pecea-.

34 BIOGEOGRAPHY Afternoon Session ries, ground sloths, marmots, and extinct carniv- Binghamton, and possibly across Massachusett s ores. at Northampton . The Peorian loess overlying the Iowan drift Between the Cary drift and the overlying contains numerous shells of many kinds of snails , Valders drift at Two Creeks near Two Rivers , some that live in dense moist forests, some in Wisconsin, about 80 miles north of Milwaukee , forest borders, and some in relatively dry prairies . was found a forest bed including remains o f In general their positions within the loess recor d spruce, birch, jackpine, nineteen species of mosses , a history of loess deposition on wooded uplands and seven species of mollusks. Stumps of tree s that became progressively more xeric. Like the stand there in varved clays. Their tops are modern forms they also show progressive varia- broken toward the southwest. According t o tions from south to north and from east to west . Thwaites the history to be inferred is as follows : On the whole they indicate a climate much lik e "(a) a recession of Third Wisconsin ice fro m that of the present . The vegetation may have in- Lake Michigan with deposition of varved clays, n (b) freeing of Straits of Mackinac with conse- cluded a larger representation of conifers, as i quent lowering of water level to one below th e Minnesota and Wisconsin today . present as shown by drowned valleys from Mil- Whether the Iowan ice sheet entirely melte d waukee south, (c) invasions of life forming th e away at that time is not known, but probably i t forest bed, (d) drowning of forest bed by water s shrank back at least a few hundred miles . from advancing ice apparently before the Strait s were again blocked, and (e) knocking down o f live trees by advancing ice which deposited re d Tazewell substage till." Before the Peorian loess had a chance to be - These trees suggest a climate cooler than th e come weathered, another ice sheet from the Lab- present, perhaps like that of northern Minnesota rador center spread southwestward over Illinoi s today. as far as Rockford, Peoria, Decatur, and Shelby- ville, and deposited a sheet of till called the Taze- Mankato-Valders substage well drift. Traced eastward its terminal moraine s In late Wisconsin time coalescent ice sheets cross central Indiana and Ohio, northwester n of the Mankato-Valders substage again entere d Pennsylvania, southern New York, and northern north central and northeastern United States from New Jersey to join the Ronkonkoma moraine of the Keewatin, Patrician, and Labrador centers . central Long Island and its apparent extensions o n At their maximum expansion these glaciers ha d Block, Martha's Vineyard, and Nantucket islands , extremely lobate outlines that are readily trace d and perhaps also on Cape Cod. A series o f much of the way by the fresh end moraines de - prominent recessional morainal loops at Bloom- posited around their borders. The edge of th e ington, Illinois, is correlated with similar moraines Keewatin ice is marked by the well-known Alta- in eastern Indiana and western Ohio and with the mont moraine across North and South Dakota, Harbor Hill moraine on northern Long Island through a southward loop in the James River and its eastward extension in Rhode Island and Valley in South Dakota, around a re-entrant a t southeastern Massachusetts . the Sioux highlands of southwestern Minnesota, and around a large lobe in the Minnesota Rive r Cary substage Valley, from which a spur extended northeast The Cary glacial substage soon succeeded the beyond St. Paul and a large branch crossed the Tazewell substage, and another expansion of the divide southward into Iowa as far as Des Moines. ice occurred from the Labrador center at the Its deposits form the Mankato till sheet or young same time that ice spread southward from the gray drift. On the east this Keewatin ice wa s Patrician center. On account of different posi- held back by the height of land in central Min- tions of the lobes of ice and the different direc- nesota, although one subordinate tongue of ic e tions of movement of the ice sheets, the Car y did spread eastward around the north side of this drift locally overlaps the earlier Tazewell drift , obstruction . especially in the area of the so-called young re d At the same time or only slightly earlier ic e drift of eastern Minnesota and northern Wiscon- from the Patrician center expanded through th e sin. The terminal moraines of the Cary substage basin of Lake Superior onto northeastern Min- extend from Cary, Ill ., in a loop around the south nesota, northern Wisconsin, and upper Michigan . end of Lake Michigan, across lower Michigan, Its deposits are reddish from the iron-bearing through another broad loop south of Lake Erie, rocks of the Lake Superior region . One lobe o f and thence across New York past Elmira and ice expanded south over the site of Lake Michi-

Afternoon Session ALLISON-PLEISTOCENE AND POSTGLACIAL CLIMATE 3 5 gan as far as Milwaukee, but covered only the In most such correlations an equivalent of th e northern periphery of lower Michigan in a series Illinoian is not recognized . The problem of its of loops through Gaylord and around Sagina w apparent absence and the related one of the statu s Bay to Port Huron . Farther east its edge i s of the Durango stage and its correlatives in the thought to have passed through central Ne w Rocky Mountains deserve further study . York, northward around the Adirondack high- land, down the Champlain lowland and eastward CLIMATIC EFFECTS IN THE GREAT BASI N again over the northern third of Vermont and Pluvial lakes New Hampshire to connect there with the St . The presence of the Cordilleran and Keewatin Johnsbury moraine. ice sheets profoundly affected the courses of the The Mankato drift generally ranges betwee n cyclonic storm-tracks across the United States. 30 and 50 feet in thickness . Since the Mankato- Instead of entering from British Columbia o r Valders ice lobes melted away, their till sheet s Alberta as many of them do now, the cyclonic have been leached of calcareous materials to a storms were shifted southward to Oregon, Cali- depth of only 12 to 2i feet and oxidized only in fornia, Nevada, Arizona, and Utah, thus bringin g the uppermost 2 to 3 feet . The freshness of the to the Great Basin greatly increased precipitation materials contrasts vividly with the more highly in summer as well as in winter . The area became altered older deposits . well watered and no doubt bore vegetation ap- CORRELATIVE GLACIATION IN THE WES T propriate to a humid climate. The runoff accu- Canadian Cordillera mulated in enclosed basins to form lakes, and as In western Canada snow and ice accumulate d the cool summers did not permit much evapora- over what is called the Cordilleran glacial cente r tion these lakes grew to be large and deep . Many in latitudes 55° to 60° N . to form an ice sheet such pluvial lakes are known, but among the m 1,200 miles long, 200 to 400 miles wide, and man y Lake Bonneville in Utah and Lake Lahontan i n thousands of feet thick . Although hemmed in Nevada are outstanding. Lake Bonneville at its and impeded by the Coast Range on the west an d maximum was about 1,000 feet deep and covere d the Canadian Rockies on the east, tongues o f about 19,000 square miles. Lake Lahontan wa s glacial ice nevertheless were discharged on all more than 500 feet deep and had an area o f sides . Intermontane and valley lobes sprea d about 9,000 square miles . Smaller lakes 200 to southward into the Puget Sound lowland as fa r 300 feet deep occupied basins in south central as Chehalis, into northeastern Washington as fa r Oregon, as in Warner Valley, Summer Lake - as Waterville and Spokane, and into norther n Chewaucan-Abert Lake basin, Fort Rock Valley , Idaho and northwestern Montana. At least two and Catlow Valley . stages of such glaciation have been recognized. In Pluvial stages the Puget Sound area these are called the Ad- Gilbert recognized two distinct high wate r miralty and the Vashon, the latter apparentl y stages in the history of Lake Bonneville. These equivalent to the Mankato or late Wisconsin o f he named the Bonneville and Provo stages . Their the Middle West. history has been reexamined recently by Antevs , Mountain glaciation who correlates the highest or Bonneville shorelin e Two to four stages of mountain glaciatio n with the Tahoe or Iowan glaciation, and the lower have been differentiated and variously named i n or Provo shoreline with the Tioga or Mankato the eleven western states. Blackwelder has glaciation. Similar sets of dual shorelines hav e worked out a fourfold series in the Sierra Nevad a been discerned by Allison in south central Ore- of California, named the McGee, Sherwin, Tahoe , gon, and likewise assigned Tahoe and Tioga ages . and Tioga stages. These he correlates with the Thus the Pleistocene chronology can be extende d Nebraskan and Kansan stages and the Iowan and to areas lying well beyond the limits of glaciatio n Mankato substages elsewhere. At Yosemite Val- proper. ley the Nebraskan and Kansan are represented b y It is of special interest that the pluvial lakes the Glacier Point and El Portal stages and th e were in their waning stages but definitely still in Wisconsin by two maxima. In the North San- existence in northern Lake County, Oregon, at tiam River Valley of Oregon the Mehama, De- the time of the climactic eruptions of Mount Ma- troit, and Tunnel Creek stages, named by Thayer , zama at Crater Lake and of Newberry Volcano, are correlated with the Sherwin, Tahoe, an d as shown by layers of pumice from these source s Tioga stages of California . in the upper part of the pluvial lake sediments .

36 BIOGEOGRAPHY Afternoon Session Further clues to the pluvial climate and humi d renewal of glaciers in the mountains, and the re - vegetation are furnished by the bird and mamma l birth of certain lakes . fossils obtained from the pluvial lake sediment s at Fossil Lake, Oregon . The bird list includes LENGTH OF POSTGLACIAL TIM E 35 genera and 41 species, mostly of grebes, geese, Four principal methods have been used to and ducks, but with smaller numbers of eagles , measure in years the time which has elapsed sinc e hawks, owls, gulls, curlew, tern, Virginia rail, etc. the last glaciation in Europe and North America . Among the mammalian fossils horses are most These methods are based on (1) the recession o f abundant, but the fauna includes elephants, cam- postglacial waterfalls, (2) the growth of delta s els, ground sloths, peccaries, antelope, dire wolf, in Swiss lakes, (3) seasonally banded deposits o f timber wolf, coyote, fox, puma, ocelot, bear, bea- silt and clay, called varves, that were laid down in ver, badger, mouse, gopher, and rabbit-a total of lakes along the margins of the retreating ice, and 23 species. The browsing and grazing mammal s (4) calculated variations in summer temperatures in particular imply the presence of woods an d according to the hypotheses of Milankovitch , grassy plains instead of the present sagebrush - Koppen, and Spitaler. covered rocky desert. By recession of waterfalls POSTGLACIAL CLIMATE S Since St. Anthony Falls of the Mississippi Evidence derived from diverse unrelated River first plunged over a cliff near Fort Snell- sources such as pollen profiles in peat bogs, the ing, Minnesota, it has receded to Minneapolis, a salinity of certain lakes in the Great Basin, the total distance of nearly 7 miles. Its average rate history of modern glaciers, arroyo cutting in the of retreat in modern times has been nearly 2 1 Southwest, studies of erosional effects of the feet a year. At that rate the cutting of the gorge wind, etc ., indicate that the cool moist climate o f between the present site of the falls and For t Late Glacial time was succeeded by a warm dr y Snelling would have required about 15,000 years . climate. Between 8,000 and 4,000 years ago the But before the falls began, the Mankato ice ha d climate had become warmer and drier than the melted back about 700 miles from Des Moines , present. Mountain glaciers disappeared, lakes Iowa. This shrinkage at an estimated rate of 400 dried up, and the wind eroded basins in the lake- feet a year would have required an additiona l beds by deflation . This period of maximum 10,000 years. On this basis the climax of th e warmth and drought is shown especially well by Mankato substage was reached about 25,000 years the pollen profiles studied by Hansen in the Pa- ago . cific Northwest and by others elsewhere . During Similar calculations have been applied to Ni- the last 4,000 years the climate in Europe, New agara Falls, with somewhat comparable results , England, the Middle West, the Pacific North - but we now know that the history of Niagar a west, and presumably elsewhere has been some - Falls has been very complicated . In consequence what cooler and moister again . The vegetatio n the necessary incorporation of various estimates changed, glaciers were reborn in the mountains , of time in the adjusted computations make th e lakes reappeared in the Great Basin, etc . The figures so derived of uncertain validity . trend of the past few centuries, however, a s By growth of deltas shown by tree rings, seems to be toward increas- Certain Swiss lakes came into existence whe n ing dryness . the late Pleistocene glaciers withdrew from their Thus the Late Glacial and Postglacial climati c basins. Into these lakes deltas have been buil t stages include : first, a cool moist period of wan- that at present rates of growth would require ing glaciation to about 15,000 years ago ; second, 14,000 to 20,000 years. From these figures Penck a period of rising temperature and decreasin g and Bruckner arrived at an estimate of 24,00 0 precipitation, with resultant recession of the Lat e years for the age of the last glacial stage in tha t Wisconsin glaciers and gradual subsidence of th e area. pluvial lakes ; third, a period of maximum warmth and dryness, 8,000 to 4,000 years ago, with com- By counting of varves plete deglaciation of many western mountain s A typical varve consists of a light colore d and complete evaporation of lakes in the Grea t layer of silt deposited in a proglacial lake in sum- Basin ; and fourth, a return to somewhat cooler, mer and a thinner layer of dark clay deposite d moister conditions during the last 4,000 years , in the following winter. These annual layer s with appropriate changes in the vegetation, the were recognized and counted for the first time by

Afternoon Session ALLISON-PLEISTOCENE AND POSTGLACIAL CLIMATE 37 a famous Swedish geologist, Baron Gerard De- reached a minimum just 22,000 to 25,000 years Geer. By matching the contemporaneous layer s ago. The next previous minima were 27,000 and from hundreds of former lake sites along the 115,000 years ago . The agreement between th e shrinking ice front, DeGeer was able to piece to- 22-25,000 year figure and that obtained by th e gether a complete record of the recession of th e other three methods lends some credibility to th e ice from southern Sweden until about 3,000 year s method. after the icecap split into two parts near Lak e Other methods Ragunda northwest of Stockholm . Later Liden Other proposed methods of measuring post- found additional varves which extended the serie s glacial time include the rate of peat accumulation , to the present day. the rate of crustal upwarping, the recession o f By this varve chronology the ice extended t o wave-cut cliffs, the accumulation of talus, the rate southern Sweden about 15,000 years ago, the of ice retreat as judged by swell-and-swale topog- Baltic Ice Lake was drained in the year 7,91 2 raphy, the rate of spread of vegetation such as B .C. (9,859 years ago), and the Ragunda bipar- nut-bearing trees, the inherited polarization o f tition, which marks the beginning of Postglacial magnetic particles in the glacial drift, and others. time in Sweden, occurred in 6,839 B .C. (roughly None of these gives an unequivocal answer. 8,800 years ago) . The earlier Daniglacial and Pomeranian or Great Baltic morainal systems are Conclusion estimated indirectly to be at least 18,000 and The four main approaches to the problem, about 30,000 to 35,000 years old respectively. although diverse, yield a value of about 25,00 0 Antevs and others have made similar varve years for the time elapsed since the climax of counts from Long Island to Ontario, but not the last substage of the Wisconsin glaciation . without gaps. On the basis of these partial Postglacial or Recent time in any particular area records and geological estimates of the time gaps, began as soon as it became free of ice . As the Antevs now assigns an age of 25,000 years to the withdrawal of the ice sheets released differen t St. Johnsbury moraine in Vermont, and of 38,00 0 areas at different times, some event must b e and 40,000 years to the Harbor Hill and Ronko- chosen arbitrarily as a reference to give a definite koma moraines in Long Island. Bryan and Ray meaning to the term Postglacial . Many glacial obtain figures of 22,300 for the age of the St. geologists follow the lead of DeGeer, Sauramo , Johnsbury moraine and 28,400 years for the Har- and Antevs in setting the end of the Pleistocene bor Hill moraine, and against considerable oppo- and the beginning of the Recent at the time when sition correlate the Ronkokoma and Cape Co d the Scandinavian ice sheet had dwindled to suc h moraines with the much earlier Iowan substage . a degree that it separated into two parts nea r Lake Ragunda, about 275 miles northwest o f By variations in summer temperature s Stockholm, about 8,800 years ago . Spitaler, and Koppen and Wegener have at - Except for minor remnants the glacial ice tempted to explain the succession of glacial cli- thus divided disappeared from Sweden about mates as the result of lowered summer tempera- 7,000 years ago. All time subsequent to the bi- tures brought about by periodic variations of th e partition of the ice at Ragunda may be calle d astronomic relations of the earth . The theory is Postglacial in a restricted sense. No event too technical to be treated in detail here . It takes strictly comparable with the bipartition of the re - into account the variations of the heat received treating ice sheet at Ragunda has been found in from the sun caused by perturbations of the ob- the late Pleistocene record of North America . liquity of the ecliptic, the eccentricity of th e However, Antevs is of the opinion that a re - earth's orbit, and the procession of the equinoxes . advance of the Labradorian-Patrician ice shee t These perturbations have cycles of about 40,000 , north of Cochrane, Ontario, about 200 miles nort h 92,000 and 21,000 years respectively . of Lake Huron, followed immediately by rapi d The net effects of these changes have been retreat of the ice, is probably equivalent in tim e computed by Milankovitch for different latitudes to the Ragunda stage in Sweden, and hence may and for winter and summer seasons for the las t be dated at 9,000 years ago also . The earlier wan- million years . In these calculations no account is ing stages of the ice since the last climax o f taken of possible variations in the total output o f glaciation constitute Late Glacial time and later heat by the sun . time is Postglacial or Recent . Kay and Leighton , The computations show that for latitude 45 ° Flint, and others prefer to include the Recent N. to 65° N. summer temperatures should have with the Pleistocene.

BIOGEOGRAPHY Afternoon Session LENGTH OF THE PLEISTOCENE AND The general agreement of these dates with ITS SUBDIVISION S Penck's estimates, the duality of the first three Penck's estimates glacial stages and the relatively great length o f Taking into account the relative positions o f the second interglacial are worthy of note . moraines and terrace gravels, the depth of weath- The dates of the last two substages of the last ering, the accumulation of travertine, and th e glaciation agree fairly well with other estimate s extent of valley deepening in interglacial stages , of the. age of the Iowan and Mankato substages Penck and Bruckner estimated the duration o f in North America, but the summer minimum at the Pleistocene as follows : 115,000 years ago has no known glacial counter- Wurm or 4th glacial 24,000 years ag o part in this country. Perhaps it has been over - 3d Interglacial 60,000 year s looked by reason of faulty correlation. Possibl y Riss or 3d glacial ? certain puzzling moraines of the West, notabl y 2d Interglacial 240,000year s the Durango in Colorado, may fit that position . Mindel or 2d glacial ? s table the three earlier glacial stages 1st Interglacial 60,000 year s By Zeuner Gunz or 1st glacial ? are somewhat younger and the entire Pleistocen e Total length of Pleistocene 600,000 year s somewhat shorter than generally supposed. This table of absolute dates has not yet ha d American estimates adequate criticism. Possibly other arrangements Using the time since the climax of the las t &lay be found to fit the radiation curves . Minima glaciation as a measuring stick, numerous Ameri- found by Milankovitch between 600,000 an d can and Canadian geologists have attempted t o 1,000,000 years ago lre disregarded by Zeune r estimate the ages of the earlier glacial stages . without any explanation. The summer radiation Representative estimates follow. Kay estimated theory is offered not as a cause of the Pleistocene post-Mankato time to be 25,000 years, the age o f glaciation but only of its periodicity and timing. the Iowan drift 55,000 years, and the lengths o f If the table proves to be dependable as Zeune r the Sangamon, Yarmouth, and Aftonian inter- believes, then a method is at hand for the abso e glacials to be 120,000, 300,000, and 200,000 years. lute dating of changes of sea level, raised beaches , If 50,000 to 100,000 years each be added for th e river terraces, glacial lakes, peat beds, and a length of the Illinoian, Kansan, and Nebraska n large number of archaeological sites . It seems po- glacial stages, the total duration of the Pleistocen e tentially of great importance, if validated, but so and Recent amounts to 850,000 to 1,000,000 years . far it has not received much acceptance or sup- Antevs dates the Iowan, Tazewell, 'Cary, an d port. Mankato-Valders substages of the Wisconsin gla- ciation at 65,000, 40,000, 27,500, and 25,000 year s respectively . APPLICATIONS OF THE CHRONOLOGY From nearly all such estimates one notes tha t the mild climates of the interglacial •stages per- The chronology of Pleistocene and Postglacial sisted longer than the cold wet climates of th e time, especially of the last 25,000 years, is ver y glacial stages . In other- words the glacial stage s useful in dating a variety of geological, paleon- were mere episodes in the climatic history, even tological, and archeological subjects. With its of the Pleistocene . aid we can derive approximate dates for the erup- tion of Mount Mazama and the formation o f Zeuner's estimates Crater Lake, the eruptions of Mount Baker , Using the Milankovitch tables of summer ra- Mount St . Helens, and Newberry Volcano . We diation, Zeuner finds that the glacial and inter- also can date climatic changes, changes of fauna s glacial stages should have occurred as follows : and floras, pluvial lake shores 4nd sediments , river terraces, glacial lakes, soils, and changes i n 13d climax 25,000 years ag o Fourth ("Last ") glacial 2d climax 72,000 years ago the outlines of the Great Lakes and of the Balti c 1st climax 115,000 years ago Third interglacial (60,000 years long ) Sea. Probably most important of all, we can de- f 2d climax 187,000 years ago termine the age of the occupation sites of prehis- Third ("Penultimate ") glacial 1st climax 230,000 years ago Second interglacial (190,000 years long ) toric man, especially in western Europe . The . (2d climax 435,000 years ago interrelations of these matters permit the assem- Second ("Antepenultimate") glacial . 1st climax 576,000 years ago First interglacial (60,000 years long) bling of diverse data like pieces of a jigsaw puzzl e into a -consistent and meaningful picture in the First ("Early ) glacial { Id2d climax 550 ;000 years ago " climax 590,000 years ago stream of time. Total length of Pleistocene 600,000 years 1,141 rA

Afternoon Session GUNTHER-EARLY MAN IN THE PACIFIC NORTHWEST 39

SELECTED BIBLIOGRAPHY Hansen, Henry P ., Postglacial Forest Succession, Cli- (Additional references are given in the works cited . ) mate, and Chronology in the Pacific Northwest, Amer. Phil. Soc ., Transactions, vol . 37, pt . 1, 1947. lison, Ira S ., Pumice Beds at Summer Lake, Oregon , Kay, George F., et al ., The Pleistocene Geology of Iowa , Geol. Soc . Amer., Bull ., vol. 56, p . 789-808, 1945. Iowa Geol . Survey, Special Report, 1943 . Antevs, Ernst, Correlation of Wisconsin Glacial Maxima , Amer . Jour. Sci., vol . 243A, Daly Volume, p . 1-39, Leighton, M . M., and MacClintock, Paul, Weathere d 1945 . Zones of the Drift Sheets of Illinois, Jour . Geol. vol . 38, p . 28-53, 1930 . Flint, Richard F., Glacial Geology and the Pleistocen e Epoch, John Wiley Sons, New York, 589 pages , Thwaites, F . T ., Outline of Glacial Geology, Edwards 1947. Bros ., Ann Arbor, Mich ., 119 pages, 1941 . Flint, Richard F ., et al ., Glacial Map of North America , Zeuner, Frederick E ., Dating the Past-an Introduction Geol . Soc. Amer ., Special Papers no . 60, 37 pages to Geochronology, Methuen Company, London, 44 4 and map, 1945 . pages, 1946 .

EARLY MAN IN THE PACIFIC NORTHWES T ERNA GUNTHE R

It is quite proper that a discussion of biogeog- of many languages . All this could not have bee n raphy should not only include man, but put him done in a period of 3,000 years which Spinde n last on the program. We have spent a day re- once announced to a startled audience was th e viewing the eons of time which preceded his ap- total of man's occupation of the New World. pearance among the mammals . Our last speake r By what means are these two purposes to be brought this review down to post glacial time s accomplished? The dating of man's entry into and prepared the scene for the arrival of man i n America must be done by correlating all the mos t the New World by describing the climatic condi- ancient finds and arriving at the earliest datable tions which greeted him here . remains. Then at least we can say, "At present, It is no longer necessary to prove to the we have nothing beyond this point in time." The American anthropologist that the American In- phrase, "at present," is very important here. dian discovered this continent and entered it by Constant work is being done and so many earlie r way of Bering Strait, but two important prob- finds are brought up for review again and again, lems still remain unsolved : when this happened, that the picture changes with every issue of majo r and by what route or routes early man migrate d journals and series. on this continent. Juggling with the date when To date archaeological finds are of such an- man made the momentous discovery of a ne w tiquity the anthropologist must call for help from continent-and probably did not know it-has several other scientific fields. We have hear d been one of the major concerns of archaelogists . how the glacial geologist can analyze climatic con - Conservatively it has usually been stated as some- ditions ; the geologist can tell of changes in th e where between 10,000 and 25,000 years ago, but earth's surface ; the botanist and zoologist can that gives too great a margin for error . Every enumerate the food possibilities for early man . new find made on the North American continen t The movement of man into America is th e is important only if the discoverer can claim fo r subject of interesting speculation on the part of it greater antiquity than for any preceding one . nearly every American anthropologist . What After a flurry of such claims, most finds prov e started man on his journey and why did he kee p to be entirely spurious, or a more recent date is it up? I like to think of those Mongoloids a s assigned to them. The trend has been, though, fishermen who had that eternal urge of ever y consistently to give man more time for his migra- good fisherman, namely, to see what is in the nex t tion through America, for his development of a stream. This movement was not a consciou s complex and varied agriculture, for the buildin g march in closed ranks but a gradual infiltration . of several high civilizations, and for the growth Dr. Douglas Leechman has stated that if thes e l

I il

6

aICci.. 1.

40 people moved as little as two miles a year it woul d Washington. Since every visit to a reservation 4 take only 5,000 years to go from the Yukon to revealed the death of yet another old informant; • the southern extremities of South America . I felt it was a crucial matter to record ethnog- In this same article Dr . Leechman mentions raphy and linguistics with the idea that archae- the fact that more work on the mapping of thes e ology has kept so long, it can last a little longer . migration routes has been done in libraries tha n Unfortunately this supposition is not altdgethe•r• at the sites. He, however, had the opportunity o f correct. Archaeology was fairly well preserved working along the Alaskan highway and found until recently when many sites that were desirable some significant material. The artifacts he dis- for the Indians also have proved acceptable for covered resemble neolithic material from North - modern habitation . The historic sites enumerated eastern Siberia and also compare with piece s by living Indians on the shoreline between Seattle - found in the same region by Frederick Johnso n and Tacoma have all become private property and • in 1944. The culture is tentatively dated at 7,000- many modern houses have been erected on-them., 9,000 years ago . All these finds were made alon g Two years ago a survey party from the Univer- routes leading into the interior of Canada . At sity located some house pits along the Columbi a each of these sites materials were found at on e river. A year later another party could not find - level only, indicating a relatively brief occupancy . them. Why? Because in the meantime a corn I believe this approach to be a very importan t patch, some cucumbers and some pumpkins had. . one, for after bringing the Indian over from been planted there after the farmer had carefully Asia, the scientist cannot let him vanish into th e filled in the house pit depressions-. Now I realize fogs of Alaska, only to pick him up again at th e that the urgency for archaeological investigation -is - Cochise sites of the Southwest . almost as great as that for ethnography. We are • It is also significant that the oldest remains trying in our department to correct our errors asj of man in America have been found in the interio r rapidly as possible. . of the continent . Geology tells us that corridors -Before going any further with this discussion, in the glaciers allowed man, and the fauna an d the area under consideration should be defined . flora he needed -to sustain life, to reach this area Usually the Northwest coast as a culture area i s when other parts of the continent were still gla- limited to the coastal strip from Northwester n ciated. This of course infers that man came i n California to Yakutat Bay in Alaska . Within immediately after the peak of the last glaci,lti,e u his tesriiacy several major and minor subarea s before the disappearance of the ice . In other can be distinguished, but a few fundamenta l words, all the results so far indicate -that the Pa- traits of material culture bind the whole region cific Northwest, even though geographically s o together. Everywhere fishing is more importan t close to Asia, was not an early habitation of man than hunting, vegetable foods were obtained by in America . gathering, dugout canoes are the main means o, f Referring again to Dr. Leechmans paper, he transportation, wood is used for houses, utensil s says : and art. The fish used is primarily salmon, which It has frequently been suggested that one of the on the coast is trolled and in the rivers speare d most obvious routes of migration would be along th e at falls and caught in nets . On the basis of the coast . It is difficult to believe that this route was fol- lowed except in recent times, unless the people had bette r dependence on salmon, Wissler has defined a and more seaworthy canoes than we suspect. It is a larger area than the coastal strip as the salmo n notoriously perilous coast . Dangerous tide rips, sudden area. This includes the territory which is ordi- and violent storms, thick fog, and a dense vegetation narily designated as the Plateau the Inter- . which makes travel almost impossible, all combine t o discourage movement along the shores, especially when mountain culture area. The basic connection - be- the comparatively dry and open interior plain is such a tween this region and the coast can be demon- short distance inland? strated archaeologically and is one of the principa l I agree heartily with this statement and up to factors in the analysis of Northwest coast archae- the present the archaeological work in the North- ological culture. This relationship is all .the more. west bears out this contention . As I read the re- apparent if one accepts Kroebers analysis of th e sults of the meager work which has been done in successive stages of Northwest coast culture . He this area I often see an accusing finger pointed states that it was first a river culture a exempli- at me. For almost the last two decades I have fied by many of the up-river peopleof today . been instrumental in organizing the field work in Then more tribes moved down to the mouths af$ ' 2Leechman, Douglas, Prehistoric Migration Routes Through , the rivers and became a beach culture as for.-.ex ` `- the Yukon, Canadian Historical Review, December, 1946 . p . 386 . 2Leechman, p. 385 .

Afternoon Session GUNTHER-EARLY MAN IN THE PACIFIC NORTHWEST 41 ample the Klallam, the Lummi, the Songish o f which Kroeber uses in his historic ethnologica l today, and the final step was the development o f analysis : the northern maritime, including the a sea going culture like that of the Nootka an d Tlingit, Haida and Tsimshian ; the central mari- the Haida .4 In the same study Kroeber divide s time from Queen Charlotte Sound to Milban k the coast into seven subareas, beginning in th e Sound ; and finally the Gulf of Georgia to Puget north : the Northern Maritime which includes Sound. The northern maritime area shows two the Tlingit, Haida and Tsimshian ; the Central outside influences, one from the interior and th e Maritime, the Nootka and Kwakiutl ; the Gulf other from the southwestern Alaskan variants o f of Georgia centering around the Salish people o f Eskimoid culture . The central area shows itsel f southeastern Vancouver Island and the mainland to be most free from outside influences except opposite ; Puget Sound ; the Lower Columbia ; the the Bella Coola whose relatively recent arriva l Willamette Valley ; and finally the Lower Klam- from the interior is known . In the Gulf of ath. It is very significant that what archaeologica l Georgia and Puget Sound region likenesses t o work has been done indicates the same general the northern maritime culture occur which em- divisions. This points to one of the most funda- phasize the distinctiveness of the central, Mil- mental features of Northwest coast archaeology , bank Sound to Queen Charlotte Sound area . namely, that all material found up to the present Since no stratigraphy has been worked out it is time is relatively recent ; in other words, we are impossible to say whether these interior influ- dealing with an area where the linguistic affilia- ences are early or late. At least in one extensive tions of modern tribes, the historic ethnographic site, the famous Eburne mound in the Frase r distributions and the archaeological material form Delta, they appear to be late. In this region some a continuous history. of the most consistent archaeological work on the The relationship between this coastal area and coast has been done including Eburne itself, the the plateau or intermountain region can also b e sites at Port Hammond, a short distance up th e traced through all of these factors . Just as one river and at North Saanich on Vancouver Island can follow in a minor way the gradual movemen t opposite . These sites give one of the few indi- of tribes down the smaller river valleys to the cations of a population and a culture change in coast so there were probably earlier also great the Northwest . When the Eburne mound wa s movements down the two principal river valleys first excavated Harlan I . Smith, who made the of the area, the Fraser and the Columbia . If it is first scientific archaelogical survey of the North - agreed that early man came into the interior of west coast, uncovered there a long headed popu- the continent and then migrated southward along lation in the lowest levels which later seemed t o the Rocky mountains, he could have found hi s be absorbed by a broad headed population . This way into the valleys of these rivers near their transitional population was best developed at head waters toward the Continental divide. Eburne although the long heads were also found The most extensive recent survey on the coas t at North Saanich superseded by broad heads, bu t was reported by Dr. Philip Drucker.' He worked no indication of a period of mixture . While it is in the northern subareas of the coast but prob- too soon to make any final statement, it appears as ably his findings will be repeated when a similar though this situation might repeat itself on th e survey is completed for the more southerly region . San Juan islands where work is in progress now. His conclusions after testing sites from Princ e This series of closely related sites also reveal s Rupert to River's Inlet are the following : some artifacts of an Eskimoid type which ma y 1. There is little difference between the archaeo- indicate an early population that had come down logical and ethnological cultures . from the north which was absorbed by the people 2. The extent of winter sites points to long occu- who advanced down the Fraser River . pation by a fairly dense population, especially It is important in consideration of the devel- since they were occupied only part of the year . opment of Northwest coast culture that in those 3. There is no key to dating. two areas where it was possible for influence s from the interior to reach the coast, their effect s This survey furthermore concludes that ar- were noticed in the archaeological remains as wel l chaeologically three subareas can be defined in th e as in the historic cultures . The "massive carving" northern part of the Northwest Coast, the same of stone figures which can be followed into the ,Kroeber, Cultural and Natural Areas of North America . interior as far as eastern Oregon is a case in U . Cal. P.A.A.E., vol. 38 :28. ,Drucker, Philip, Archaeological Survey of the Northern point. The style has many features that ma y Northwest Coast . Bureau of American Ethnology, Bulletin 133 , 1943 . well be the basis of Northwest coast art and fur-

42 BIOGEOGRAPHY Afternoon Session ther work may reveal a focal center in the modern this was not also true in the prehistoric period . Salish area and a subsequent movement north - Again the Iack of great depth in archaeological ward. Mr. Paul Wingert at Columbia University finds signifies brief occupation. It is of course has been working on this problem and it is hoped hoped that as this area is more thoroughly worke d that the results of his efforts will shed new light and especially more caves explored, earlier level s on an important aspect of Northwest coast eth- will be discovered . nology. It is an answer to those scholars who Finally in analyzing Northwest Coast cultur e look upon Northwest coast culture as entirel y one comes back again to stressing the recency o f apart from the main stream of American India n it, not only of the Indian history but also o f development. And again here the archaeology European contacts. The early Spanish voyage s and ethnology go hand in hand . Linguistically along the coast did not often land their men for we know the relationship between coast and in- more than securing wood and water. In the north terior Salish ; historically we know of the trading the Russian contacts beginning with Bering in activities of the Chinook up the Columbia River . 1741 brought the first day-to-day relationship s As a fellow anthropologist once tersely charac- with Europeans and the use of European goods . terized the Chinook situation, "They potlatch with Within a century of that time, by 1835 the Hud- horses." In spite of these external influences the son's Bay Company had complete control of th e Northwest coast culture has developed steadil y region from Taku, which it leased from the along its own characteristic lines, not undergoin g Russians, to the Columbia River . From the de- some of the drastic cultural changes which oc- scriptions of observant travellers, like Cook an d curred in the central Plateau region that resulte d Vancouver, it is apparent that the material set- in a veneer of Plains material culture . These ting of Northwest coast culture as it was known flashy and familiar Plains costumes fill the eye t o in the historic period was already well estab- such an extent at first glance that they often ob- lished. It was also clear that the population was scure the simple Plateau salmon fisherman, wh o not as great as it had been, for too many villag e divested of this recent finery stands at some o f sites were unoccupied to be attributed to seasona l the great falls of the Columbia getting his "staff habitation only. In the fifty years of contac t of life" in the same manner as he did before the with Russians which preceded Vancouver 's visit adoption of the horse made his excursions into and the occasional visits of other Europeans th e the great plains frequent events . The Chinook Indians suffered many casualties through warfar e brought dentalium and whalebone clubs from th e and disease. In spite of the shrinking population coast up the Columbia and brought down th e these European contacts stimulated intense cul- river tubular pipes, cremation, mortars, metates , tural activity. Few new traits were added bu t and semi-subterranean houses . Again in th e the already existing stress on wealth and all o f Fraser Delta the influences from the interior are its ramifications was accentuated through the pres - apparent and these intrusive traits were sprea d ence of new goods to be accumulated and dis- along the coast easily through trade and visiting tributed for social prestige . The archaeology o f with the exchange of gifts. European contacts in this area is rich and plenti- It is on account of these historic trade rela- ful. In a minor recent way it also gives one o f tions which can be traced archaeologically that th e the clues so necessary for dating coast material . area of the Pacific Northwest is defined here s o In the period immediately following the days as to include the drainages of the Fraser and th e of the early explorers and the fur trade, which Columbia rivers, thus taking in all the hinterlan d might be called the salmon cannery and mission- which is culturally today called either the Plateau ary period, Northwest coast culture declined a s or the Intermontane region. There are man y rapidly as it had developed in the previous one . traits in the Plateau culture which distinguish i t But even today much ethnography can still b e from the Northwest Coast, but they are generall y secured, from men who work in logging camp s nonmaterial and on the coast late in developing. but take time out to participate in the moder n This corridor into the Plateau region further tie s curtailed form of the winter festival, from wome n the area to the main body of the American Indian who work in the canneries but have winter visita- culture through the important finds made by Dr . tions from their guardian spirits . And every- Cressman in eastern Oregon which seem to poin t where one finds these people living close to th e to the early Basket Makers of the Southwest. archaeological sites and furthermore rememberin g Within historic times this area has seen much some of the occupants . This past summer we movement and there is no reason to believe that had one student working on local place names in

Evening Session - ANTEVS-BIOGEOGRAPHICAL PROBLEMS OF NORTH AMERIC A the San Juan islands while others worked on. the this claim cannot always be made along.th-e= Col- archaeology. umbia: In the interior there is strong indicati` - In conclusion man is not early in any sense of movements of tribes, while on the coast sea, . of the word in the Pacific Northwest . He had a sonal movement is more common . I look for the ig aik(ficult terrain to conquer there, archaeology of the future to substantiate these ut once he adapted himself to it he found that conclusions with more evidence ; I doubt that the he possessed that area of America which sustained picture will change mater-ially. - • } the largest native population without the use o f Since my own research deals exclusively with agriculture. There is archaeological evidence o f the ethnological phase of this story, I wish to relationship with the interior through the great point out again in closing that I leaned heavily o n waterways. There is much archaeology still to the fine work of Dr: Drucker in his recent archae- be done. What has been surveyed indicates the ological survey of the Northwest coast as well a s continuity between archaeology_ and historicall y the Alaskan work of Dr . Leechman and the basic known tribes at least on the cekst itself, though field work of Harlan I . Smith.

BIOGEOGRAPHICAL PROBLEMS IN NORTH AMERIC A ERNST AEVS

a The subjects chosen for discussion are : the Early Man could hardly ham, spread to the Spread of Early Man to the United States ; the United States when glacial ice extended across. Movements of Plants and Animals as the Pleis- Canada from west}To east but he probably could tocene Ice Sheets Waxed and Waned (with spe- during the three following ages . First, he could cial emphasis on the problem of plant refugia have come during the Last Interglacial-Earl y around the Gulf of St . Lawrence) ; and the late wan before the Iowan ice, which formed the i t Pleistocene Extinction and Extermination o f culmination of the last glaciation, had become Mammals . extensive, or perhaps more than j0,000 years ago. Though some believe in so early an arrival, SPREAD OF EARLY MAN TO TH E no real evidence has yet been presented. Early UNITED STATES Man could probably also have arrived during th e Man seems to have arisen in southeastern Iowan-Mankato interval of reduced glaciation i n Asia, where Dr. Ralph von Koenigswald in th e the West 45,000 to 40,000 years before the pres- late 1930s discovered teeth, jaw bones, and othe r ent, when there may have been an ice-free cor- skull fragments of three new species antedatin g ridor on the east side of the Canadian Ro€kies . those previously known . These important finds Again conclusive evidence is lacking . Some, rec- extend the family of man over the last 550,000 ords of man have been tentatively dated 25,000 years, according to von Koeningswald s dating. years before the present, but that was hardly an From southeast Asia man spread to all cor- age of entry on account of extensive ice . The ners of the world. The dispersal to other parts third age of possible arrival was after and, sinc e of Asia, to Australia, Europe, and Africa was the final break in the last ice barrier across relatively unhindered and was accomplished lon g Canada. A lane was opened some 18,000 years ages ago. The diffusion to the United States, on ago or somewhat later . During the past approxi- the other hand, could take place only over the mate 15,000 years man has actually spread int o narrow bridge of the Chukotski and Seward pen- the United States . insulas in the far Arctic. As far as known from The general course of dispersal .in North skeletal remains the earliest Americans belonge d America must have been up the Yukon Rive r to modern man (Homo cf. sapiens) and were th e and its tributaries, through mountain gaps to th e ancestors of the Red Indians . They stood in a Mackenzie Valley, and southward in this valley late Paleolithic stage of culture . Since their near- and on the Great Plains. The gaps first to be - est relatives now live in central and northeaster n come ice-free, and perhaps the first to be used b y Asia, they probably derived from there. The man, were those in the north . . low divide be- diffusion into the United States proper may have tween the Porcupine and Mackenzie rivers, som e taken hundreds and possibly thousands of years . 80 miles south of the Arctic Ocean, has yielde d

.a . . ~. w . I.S

44 BIOGEOGRAPHY Evening Session old artifacts.. The principal trails were perhap s ever, and growth of the families and arrival of the . Yukon-Pelly-Frances-Liard, the Yukon-Tes t new tribes from Siberia forced man continuously lin-Liard, and the Yukon-Tanana-White Horse - .to extend his territory. Dispersal was not easy Liard routes which have been used by mammals because of bogs, swamps, dense forests, and coun- and Red Indians . The last mentioned trail, which ter current . The spread down to Lat. 60° in the also was chosen for the Alcan Highway, ha s mountains, and to 54° on the plains, was agains t given up numerous ancient artifact sites . On the streams, and these were in summer at best a reaching the Missouri River in western Montana , hindrance, but if man had no water craft a rea l some tribes surely followed this river upstream obstacle . In some regions the early diffusion through the funnel-shaped valley which led t o may have been essentially limited to the frost relatively low passes west of Yellowstone Park . season, when ice made travel easy. It seems the Therefore man probably arrived in the Grea t sun would have encouraged southward spread, Basin as early as he did on the plains of eastern yet the dispersal had been away from the sun i n Wyoming. Asia . Since the difficult tundra and taiga belt s Important sites of Early Man have been foun d grew narrower during the warm postglacial age in most of the states in the western half of th e some 6000 to 2000 B .C., these millennia were United States and near Mexico City . perhaps the main age of immigration . However, Early Man who first spread to the United man began to filter in from northeast Asia some States lived in the taiga and tundra of northeast 15,000 years ago and has continued to do so u p Asia and may have subsisted by hunting, fishing, to the present. and gathering of berries, nuts, roots, and othe r Although the southern part of the North plant products . He probably dispersed essentially Afut rrn continent should have looked like a as would a predator. He multiplied and with paradise, Early Man without delay pushed through each generation extended his ground in the di- the bottle neck and the tropical jungle of Panama rection of least competition and amplest food and through all of South America to its southern - supply. With the tundra and forest and thei r most tip, for on the Straits of Magellan Juniu s pertaining animals he occupied the land as it was Bird found artifacts in association with bones o f exposed by the retreating glaciers. So he may extinct horse and ground sloth, artifacts that are have spread along the north shore of the Sea o f surely several thousand years old . The migration Okhotsk and through the never-glaciated Penzh- route from Bering Strait to this site i over 10,000 ina and Anadyr valleys to the region of Bering miles . All considered, man occupied both Ameri- Strait. can continents in a remarkably short time . At that time, 20,000 to 15,000 years ago, se a level stood probably between 150 and 100 feet Migrations of biota caused by lower than today, because large quantities o f waxing and waning of ice sheets water were stored in land ice, while the penin- It is a rather generally accepted view that th e sulas on Bering Strait perhaps were pressed temperature fall and the growth of glaciers an d down slightly . As a consequence the shore lin e ice sheets during the oncoming of the Pltistocese,,0i: n glaciations forced plants and animals to '.migrate stood lower, perhaps fully 100 feet lower, tha ._ at present . This and the fact that a depression outward, chiefly southward, and that the biota , , of the shore . by 120 feet would possibly expose later reoccupied the land as it was freed from tile 1'. .; 1 a continuous Sibero-Alaskan land bridge mean ice. This view seems logical, and it is suppp,rted that the Bering Strait, now 56 miles wide, was by fossil remains and by modern relrict•,oc t i much narrower and broken by more islands . rences . Boreal and arctic biota may have Even if Early Man was not able to build wate r vived the glacial culminations almost everywWh te craft, he could probably cross the narrow chan- south of the terminal moraines, which were boi ;t: aT nels on log rafts in summer and on ice in winter . dered by a tundra belt judging fror-n ,fossil .fit.! . 7 Western and central Alaska and the Yuko n phenomena . The biota spread south and '• , J - . Plateau to or into the Yukon Territory wer e pecially along the Appalachian and Rocky.tnIomim;ti largely unglaciated and formed a glacial refugiu m tains. Fossil remains of the most no;rt reel' 1E for arctic and boreal biota northwest of the ic e American pine, Pinus banksiana, have been Moat ; !~. . sheets. extending from the Pacific to the Atlantic . in South Carolina, and such of Larix laritti,. A _ Thus Early Man arriving in Seward Peninsula Picea glauca, and Thuja occidentalis in Louisiana found a well-stocked though largely arctic an d Bones of musk ox, a tundra inhabitant, ham. bge ~ subarctic land . Life must have been hard, how - discovered in West Virginia, Kentucky, Arkan-

Evening Session ANTEVS-BIOGEOGRAPHICAL PROBLEMS OF NORTH AMERICA 45 sas, and Utah, and remains of .caribou in West- cupy Anticosti and the Mingan Islands, which h e Virginia and Kentucky . admitted had been completely overrun by ice o f Of course, hardy plants and animals also sur- the last glaciation . The modern stations of the vived the glaciations in other areas bordering the plants on the Great Lakes, which as mentione d ice sheets, Alaska . for instance . Some persisted were covered by Wisconsin ice, and those on even on nunataks, which is the name for ice-free Lake Mistassini halfway between James Bay an d areas, usually mountain summits, entirely sur- the St. Lawrence estuary, which stood unde r rounded by ice. While this is acknowledged by thousands of feet of glacial ice, are eloquent tes- all, there has recently been a discussion about th e timony of postglacial migrations of hundreds of extent of the glacial survival on nunataks an d miles. These plants have not lost the ability to about the associated problem : the ability or in- spread. ability of s . c. nunatak plants to migrate readily. Fourth, where did the Cordilleran plant s The discussion began in 1925 when Professo r weather the last glaciation? ' The abundant en- M. L. Fernald of Harvard distinguished plant s demism among these plants in the East speak s of American or Sibero-American affinities, which for long segregation from their western relatives , he called Cordilleran, in the coastal mountain s as Fernald pointed out . Thus at least the plant s of northern Labrador, in isolated stations al l on the Atlantic sea-board can hardly have com e around the Gulf of St . Lawrence, and on lakes from the Rockies since the last glaciation . Rather, Huron and Superior . The flora of western af- the eastern stations must have been colonized finity contains some 225 species, of which more mainly by plants which moved out before the last than 80 are of local and regional origin . Since ice and returned upon its retreat. These glacial -' this high degree of endemism suggests high age , migrants had two general regions of refuge, viz ., and the plants occur mainly in stations which i n Pennsylvania including the country to its south, 1925 were believed never to have been glaciated,l~ and the continental shelf, the modern fishin g Fernald then concluded that they had outlived al l banks which then rose above sea level . 'To Penn- the glaciations on several nunataks, though not i n sylvania there was, of course, a continuous land all of their modern eastern stations . Fernald be- route of very diversified nature which should lieved that through high age the plants had es- have furnished suitable habitats . sentially lost their ability to migrate and wer e For an approximate reconstruction of the relicts. This nunatak theory has been criticized refugia on the continental shelf it has been as- by V. C. Wynne-Edwards and discussed at lengt h sumed that shortly after the last maximum of th e by Fr. Marie-Victorin and Hugh Raup . Here eastern ice the sea level stood 300 feet lower tha n only the main problems will be reviewed . today, the water being, of course, stored in th e The first problem is : Did any of the easter n land ice. The then shoreline coincided with th e stations of the s . c. Cordilleran relicts really escap e modern shore on a line running south of Boston glaciation during the Pleistocene? Were ther e and through Nova Scotia and southern New- any persistent nunataks? All land about lakes,, foundland-the zero isobase . Thus if the late - Huron and Superior must have been completely glacial sea level stood 300 feet lower as assumed, covered by ice repeated times, but some areas i n that line also stood 300 feet lower, the crust o f Labrador and on the Gulf of St. Law- the earth being pressed down by the weight o f rence may -or may not have formed nunatak s the ice. From cross profiles of the isobases of throughout the Ice Age, the opinions of the ex- the late-and-postglacial uplift and from the as- perts being divided. sumption that the earth's crust on the isobase lin e Second, if there were nunataks, could th e minus 300 feet took the same vertical stand as i t Cordilleran plants have survived on them fo r does today, lines of equal glacial depression hav e thousands of years ? Since these plants in Labra- been drawn and the probable land has been out - dor do not grow on cold, windswept mountain s lined on hydrographic charts . but are essentially restricted to comparatively It has been found that in lateglacial time th e sheltered and favorable localities near sea level s southeastern corner of Newfoundland reache d they could hardly have survived the glaciations ' somewhat beyond the modern shore and tha t on exposed high mountains, only on low nunatak s Nova Scotia's southeast shore was at most 1 0 near the ice border . miles farther out than now. The Great Bank o f Third, are these Cordilleran plants able, o r Newfoundland formed a large island, and other unable, to migrate readily? Fernald himself as- banks south of Newfoundland and east of Nova sumed that they had migrated somewhat to oc- Scotia, moderate or small islands . Between Nova

-6 - BIOGEOGRAPHY Evening Session Scotia and George's Bank, east of Cape Cod, ther e sumed that they had immigrated on the now was a strait 120 miles wide with only a small drowned coastal plain possibly .before the Ice island. New England and Long Island extended Age, but more probably during the long second far southward . On the other hand, the coasts o f interglacial, and thus had survived at least tw o the northern two-thirds of Newfoundland and th e glaciations in the region of the Gulf of St. Law- coast of Labrador stood lower than today in re- rence. As in the case of the Cordilleran plants , lation to sea level, were somewhat drowned . some Coastal Plain plants may have lived through There were no continental shelf refugia in thos e the last glaciation on the shelf islands, but mos t regions, though some botanists have so assumed. of them may be postglacial immigrants which i s To return to the s . c. Cordilleran relict flora s suggested by intermediate stations in New Eng- in the East, those in the Labrador-Quebec-Gulf o f land. St. Lawrence regions may have survived the last glacia4ion mainly in Pennsylvania, partly on the Late Pleistocene extinction of mammal s shelf islands off Newfoundland and Nova Scotia , A short time ago geologically speaking there and possibly to some extent in small sheltered, occurred in North America an extraordinary ex- unglaciated areas about the Gulf of St. Lawrence, tinction or extermination of mammals which es- as on the Magdalen Islands, Prince Edward Is - pecially blotted out the largest beasts as the mas- land, Nova Scotia . The ranges of these flora s todons, elephants, camels, ground sloths, horses, are disrupted perhaps because the plants prefe r dire wolves, saber-tooth cats, and several species certain soils, and can compete successfully wit h of bison. In some cases the extinction was grad- other_ plants only in soils formed from limestone . ual, but largely it took place in a short space o f Before Fernald's views were moderated, Eri c time after the last glacial culmination . Hulten, a Swedish botanist, carried the ideas o f There is no generally accepted standard o f isolated glacial. refugia and of inability to spread division of the age since the maximum of the las t still farther . He believed that plants migrate too glaciation in America, and as a consequence con- slowly to have moved away from the expanding siderable confusion prevails . Personally, I place ice. of the glaciations, and that they were jus t the divj ji' ' between the Glacial and the Post- overrun and destroyed . Arctic and boreal plants glacial (the Pluvial and the Postpluvial) at th e -and animals too-survived the Ice Age in areas time when the climate in the United States and near the ice that remained ice-free even durin g southern Canada had become about as today . In the most extensive glaciation . Such glacial refugia the north this occurred roughly 9,000 years ago , were the Yukon Valley, parts of the Canadia n and far outside the glaciated areas 10,000 years Rockies, the Canadian Arctic Archipelago, th e ago. In this discussion the Recent, Postglacial , coastal mountains in Labrador, the region of th e and Postpluvial therefore signify the past 9,00 0 Gulf of St. Lawrence and the adjacent continenta l to 10,000 years. shelf, and islands and peninsulas in lakes Superio r At some thoroughly studied sites of Early and Huron. From these regions of survival- Man, as those in Cochise County in southeastern especially from the Rockies and the eastern con- Arizona, at Clovis in eastern New Mexico, Lin- tinental shelf-the glaciated areas were restocked denmeier in northern Colorado, and Abilene in with vegetation during the interglacials, but man y central Texas, bones of extinct mammals occur in s. c . rigid plants were unable to spread sufficiently beds which were deposited when the climate wa s to occupy the glaciated regions . There was some, moister and cooler than today, i .e., occur in geo- but only little, spread of plants from the region s logically dated pluvial beds . The mammals rep - south of the terminal moraines. As stated, we resented are in Cochise County : mammoth, horse, now know that some of the assumed ref ugia did large camel, dire wolf, and bison ; at Clovis : mam- not exist, that others were much smaller than moth and extinct bison ; at Lindenmeier : large Hulten assumed, and that the plants with dis- camel, extinct bison, and probably mammoth ; and continuous ranges can migrate . at Abilene : mammoth. Similary, mammoth oc- The problems of glacial survival near th e curs in geologically dated, pluvial beds in Trans - Gulf of St. Lawrence and of ability to migrat e Pecos, Texas, and at Jeddito in northern Arizona . freely have also been raised with regard to th e In all these places the bones occur only in pluvia l Coastal Plain floras in Nova Scotia, Sable Island , beds, not in the younger beds which overlie th e Newfoundland, and adjacent islands . Originally pluvial beds at most of the sites . Bones in the (1925) regarding these floras as postglacial im- younger beds belong to existing mammals . migrants from New Jersey, Fernald in 1933 as - In the Vint Ike ia.are.,-i _-_m:__1 ___i,mals

Evening Session ANTEVS-BIOGEOGRAPHICAL PROBLEMS OF NORTH AMERICA 47 have been found mostly in peat bogs . They are ably climate, the appearance on the scene of man, not well dated, but seem to derive from the late and diseases, while such long-range factors a~, x Glacial. over-specialization, low intelligence, and senility Exceptionally well preserved remains of ex- were only of secondary importance . The increas- tinct mammals are 'of special interest . Outstand- ing dryness in many regions during the late ing cases are a fresh skull of a large native camel Glacial could have led to reduction in numbers in a cave in Utah ; ligaments, skin, and hair a s and even to local extinction, though hardly to tota l well as bones of ground sloth at Aden Crater in extinction. Early Man seems to have been a southwestern New Mexico ; and skin, hair, and formidable hunter, for at Folsom in northeastern horny claws of ground sloth ; and skin and hair New Mexico there were bones of 40 to 50 bison s of horse in Gypsum Cave, east of Las Vegas, from a single kill. Perhaps he used mass killing Nevada. Such excellent reservation is generally methods, as the fire drive, as has been suggested regarded as evidence of survival to a late date, by Carl Sauer . Since man was new and unknown into the dry age of the Postpluvial some 6000-200 0 to the animals, they were probably unafraid o f B.C. Therefore it is $l'tportant that the sloth him and fell easy victims. The most important dung in Gypsum Cave contains a flora that *w cause of the extinction, however, was perhap s grows at 3,000 feet higher elevation where it is, diseases. distinctly cooler and moister. The skin and hair of sloth and horse in Gypsum Cave therefore de- SELECTED REFERENCE S rive from the Pluvial, are well over 10,000 yearst;. Antevs, Ernst., Correlation of Wisconsin glacial maxima . old. Excellent preservation does not prove post- Amer. Journ . Sci., vol. 243-A, , aly Volume, pp. pluvial age . ' 1-39, 1945 . Thus there is to my knowledge in North Fernald, M. L., Persistence of plants in unglaciated areas America no case in which a s. c. Pleistocene ex- of boreal America . Memoirs Amer . Acad. Art* tinct mammal surely survived into the Recent , Sci., vol. 15, 1925, No. 3, pp. 237-342, 1925. Postglacial or Postpluvial, as defined to the past Recent discoveries in the Newfoundland flora . 9,000 to 10,000 years . Still it is obviously possibl e Rhodora, vol . 35, 1933, pp . 80-107. that some of the mammals, as ground sloth an d Critical plants of the upper Great Lakes re- gion of Ontario and Michigan. Ibidem, vol. 37, bison, did so. And there seems to be an authenti c 1935, pp. 197-222 . case from Ecuador .prove that the mastodon Flint, R. F., et al . Glacial map of North America . Geol . stillr,lived there when the Indians knew how to Soc. of Amer., Special Pap. No. 60, 1945 . make painted pottery, that is during the early Hulten, Eric., Outline of the history of arctic and boreal part of the Christian era. biota during the Quaternary period . P. 168, 43 pls . It appears then that the remarkable disap- Thule Publ. Co., Stockholm, 1945 . pearance of the large Pleistocene mammals essen- MacCurdy, G. G., Early Man. J. B. Lippincott Co., tially occurred during the age of waning of the Philadelphia, 1937. Pk Raup, H . M., Botanical problems in boreal North Amer- last ice sheets and was almost' ompleted about ica. Bot. Review, vol. 7, 1941, pp. 147-248. 10,000 years ago . This is a strange fact, for i t Stock, Chester, Prehistoric archeology. Pp. 137-158 in seems that the opening of new lame pastures as Geology, 1888-1938 . Fiftieth Anniversary Volume, the ices shrank and disappeared wiffIid have im- Geological Society of America, 1941 . proved the lot of the mammals after the crowd- Wynne-Edwards, V. C., Isolated - arctic-alpine floras in ing during the maximum of glaciation . Never- eastern North America : A discussion of their gi g theless, the disappearance within a relatively cial and recent history . Trans. Roy. Soc. of Can= ada, Sect. V. vol. 31, 1937, pp. 1-26. short space of time suggests that the causes were } 1939. Some factors in the isolation of rar e timed. Therefore, the main causes were prob- alpine plants. Ibidem, vol . 33, 1939, pp. 1-8.