* This is Part 3 of a three-part installment of “Problematica.” The subject is the (contested) importance of Thomas Chamberlin’s theory of periodic diastrophism during the first half of the twentieth century. So far I’ve explored the origin of the theory (Part 1) and traced its many-sided influence during the 1910s and ‘20s (Part 2). But I’ve yet to answer the question I’m really interested in, which is: how big a deal was periodic diastrophism in American geology after 1930? That is the subject of Part 3, and let me entice you by saying that it includes a plot twist. (Gasp!) Problematica is written by Max Dresow…
In 1944, George Simpson observed that “[the] appearance of new groups, with unrecorded origin-sequences, frequently coincides with climaxes in earth's history— crises of mountain building and land emergence” (Simpson 1944, 112, emphasis added). It’s the kind of sentence modern readers are apt to ignore, apart from wondering, perhaps, why anyone would think to record a coincidence between the origin of taxonomic groups and the production of topographic relief. But to someone familiar with the history of geology, the sentence radiates intrigue. Why was Simpson, of all people, expressing approval for the link between mountain-building and evolutionary activity as late as 1944? And what does this tell us about the state of American geology on the eve of the plate tectonic revolution? These are questions for the present essay, which concludes a three-part investigation of the theory of periodic diastrophism in twentieth century geology.
The whole investigation was prompted by something I read a while ago: that periodic diastrophism was, in 1952, the “prevailing concept” in American geology (Henbest 1952). I caught a whiff of exaggeration. Yet stumbling across the above sentence from Simpson gave me pause. If even Simpson was down with the diastrophic theory, and as late as 1944, then who was against it? Simpson was an unlikely diastrophist. (Or was he?) So— you might reason— his apparent support for the theory is good evidence that it continued to occupy a leading position in American geology as late as 1944.
George Gaylord Simpson in his study
It is tempting to go along with this line of reasoning. However, as I cautioned in Part 1, there are reasons for resisting it. The most important is that several influential people in Simpson’s life were enthusiastic about periodic diastrophism, most notably William Diller Matthew, Simpson’s predecessor at the American Museum of Natural History. But it wasn’t just Matthew. Simpson did his PhD at Yale, which was then a key stronghold of Chamberlin’s geology. Joseph Barrell was dead, but Charles Schuchert remained a dominant presence, having concluded his term as president of the Geological Society of American just a year before Simpson arrived. And Simpson’s eventual supervisor, Richard Swann Lull, had Chamberlin-ian sympathies of his own. Putting all this together, it begins to seem as if Simpson’s support for periodic diastrophism was over-determined, at least in the early going. That’s why I cautioned against assigning too much weight to Simpson’s apparent support for the theory when trying to evaluate its popularity in the 1930s and ‘40s.
In the remainder of this essay I will try to support these claims, focusing on two pieces of writing, one from Lull, the other from Matthew. I will begin with Lull, whose support for the diastrophic theory I was unaware of when I began writing this essay. Then I will turn to Matthew, and ask how Chamberlin’s geology informed his most famous study, “Climate and evolution” (1915/1939). Finally, I will return to Simpson and draw some perhaps surprising conclusions about the status of periodic diastrophism after 1930.
The Pulse of life
Richard Swann Lull was a paleontologist specializing in dinosaurs of the Triassic Period. Originally a government entomologist, he had been converted to paleontology by an encounter with Edward Hitchcock’s Ichthological Cabinet, a world famous collection of fossil footprints including many specimens of dinosaur trackways. At the time, Lull was based in Amherst, Massachusetts: the very community Hitchcock had once called home. His love affair with Triassic reptiles began in the handsome red brick buildings of Amherst College. But soon Lull was off to Wyoming with a team from the American Museum of Natural History, charged with recovering a Brontosaurus specimen from Bone Cabin Quarry. A second trip to the West, this time to Montana, sealed Lull’s association with the Department of Vertebrate Paleontology, and in 1903 he began graduate research with department head Henry Fairfield Osborn.* Then it was off to Yale, where he would spend the next fifty years as professor of paleontology and associate curator of the Peabody Museum of Natural History.
[* Osborn was a commanding figure in early twentieth century paleontology. But as a scientist he was a mediocrity. Perhaps no one in the history of science benefited more from outrageous wealth; without this, it’s impossible to imagine him achieving any distinction as a scientist or administrator. Yet he was born to a railroad tycoon, and by pulling every favor (and appropriating the labor of many talented subordinates) he rose to a dominant position in American science. Which influence he then used to promote Nordicism and eugenics, even penning the preface to Madison Grant’s racial jeremiad The Passing of the Great Race.]
The team from the American Museum of Natural History at Bone Cabin Quarry (1899). Seated, left to right, are Walter Granger, Henry Fairfield Osborn, and William Diller Matthew. Standing are F. A. Schneider, Richard Swann Lull, Albert Thomson, and Peter Kaison
Simpson began his graduate education in 1924. At this point Lull was a well-known researcher and educator, having published his textbook, Organic Evolution, just four years earlier. Five years before that he had published perhaps his most important work, Triassic Life of the Connecticut Valley (1915). But these are not the texts I want to discuss. Instead, I want to discuss the text of a lecture that Lull delivered during the 1916–17 academic year. This was later published in a volume called The Evolution of the Earth and its Inhabitants (1918). Accompanying it in the volume were contributions by Barrell (on the origin of the earth), Schuchert (on earth’s changing surface and climate), Lorande Loss Woodruff (on the origin of life), and Ellsworth Huntington (on climate and civilization). All were aimed at a general audience, including Lull’s entry on “the more or less rhythmic accelerations of evolution shown by the fossil record” (Lull 1918, vi).
Lull’s contribution was titled “The pulse of life” and began with a picturesque image.
The stream of life flows so slowly that the imagination fails to grasp the immensity of time required for its passage, but like many another stream, it pulses as it flows. There are times of quickening, the expression points of evolution, and these are found to be coincident with geologic change. These changes are so frequent and so exact that the laws of chance may not be invoked to account for them. They stand to each other in the relation of cause and effect. (Lull 1918, 109)
Lull went on to say that this general position “does not imply the acceptance of any one philosophical factor of evolution”; one could accept this general picture and be a Darwinian, a Lamarckian, or something else. Still, “[w]hever it has been possible to connect cause and effect, the immediate influence is found to be generally one of climate, back of which lies, as the main cause, earth shrinkage and a consequent warping of the crust, with elevation and spread of the lands and the formation of mountain ranges” (Lull 1918, 109). This was so much Chamberlin-ian geotheory of the sort that was ubiquitous at the Peabody Museum. Lull even noted that the most probable cause of the last glacial period was “the great continental elevation which formed the Cascadian revolution,” indicating a close agreement with Chamberlin’s account of continental glaciation (110).
The heart of Lull’s chapter was a chart depicting the historical relationship between climate fluctuation, continental elevation, and evolution. The chart was apparently prepared with the assistance of Barrell and Schuchert; most likely Schuchert consulted on climate change and Barrell on diastrophism. The climate curve requires little explanation: “minor jogs indicate climatic oscillations; doubling of lines, climatic zones where aridity and cold are differentiated [as they are in the modern world]” (Lull 1918, 111). As for the diastrophic curve, “the upslope… signifies rising diastrophism [or continental elevation]; the downslope, the period of erosion before the continents are low enough to have mantles of sediment spread about them” (110). In line with Chamberlin’s hypothesis, period boundaries are depicted as intervals of erosion. The tangential lines show “the relation of a series of movements: a gradual rise culminating in the great revolutions.”* These are intervals of intense mountain-building, here labeled Grand Canyon, Appalachian, Laramide, and Cascadian. Notably, since the eras are not drawn to scale, the slope of the tangent lines is not equal; but if this representational feature were corrected, the slopes of the lines would basically correspond.
[* This view, in which the stages of crustal movement are grouped into “diastrophic crescendoes and diminuendoes,” was shared by Schuchert and Barrell (Barrell 1917, 888). As Barrell explained, “diastrophic movements pulse through [eras of time], the larger oscillations subsiding in the stage of quiet, rising in increasing pulses to that culmination [or revolution] which marks the close of one [era] of time, then subsiding through the initial portion of the following [era].”]
Lull’s chart, produced in consultation with Joseph Barrell and Charles Schuchert, showing the juxtaposed fluctuations of climate, diastrophism, and life (or evolutionary activity). Where the climate line is single a relative uniformity of climate conditions was supposed to have prevailed. Where it splits there was a differentiation between arid and cold zones. Dotted lines in the life curve mark “where theory precedes the recorded fact.” (The fourth Mesozoic period, labeled “Coman.”, is the Comanchean.)
Below the curves representing the physical evolution of the earth, Lull added a curve to represent “the consequent acceleration and retardation of the evolutionary stream" (Lull 1918, 110). This is difficult to interpret; apparently, it represents a grand sum of all the lineage-specific evolutionary rates, or what comes to the same thing, a measure of the evolutionary activity of the animal kingdom as a whole at some time. No units are given; on the ordinate scale it just says “Pulsations.” Still, the argument is clear enough. As Lull put the point, “The great heart of nature beats, [and] its throbbing stimulates the pulse of life” (146). This is evident in the correspondence between the curves, “between the pulse of life and the heavings of the earth’s broad breast” (144). At periods of evolutionary crisis, an upward movement of the curve signals that “expansive evolution” is the order of the day. This is a style of evolution, so named by Chamberlin, “in which new ground and rich opportunities constitute the dominant condition” (Chamberlin 1898a, 457). Later, downward movements indicate “restrictive evolution,” leading frequently to extinction. These typically, though not invariably, follow diastrophic peaks: episodes of land elevation and mountain formation involving the reduction of shallow seas.
In describing the workings of expansive and restrictive evolution, Chamberlin focused on the shallow seas (Chamberlin 1898a, 1898b). The reason is that his interest in that work was stratigraphic; it was to account for the differences in the marine faunas of successive geological periods, by which he meant the set of (mostly) marine invertebrates used to define separate intervals of time. Lull’s interests were different. More than Chamberlin he was focused on terrestrial animals, mostly large quadrupeds. These were not affected by diastrophism in the same way as shelf-dwelling invertebrates, for whom the main factor was the availability of shallow water habitats. So Lull’s account did not always follow Chamberlin’s.
An image from Chamberlin (1898), which shows, on the one hand, coastal topography following a period of relative uplift (o–o–o), and on the other, topography after erosion has carried away the coastal cliffs and deposited their sediments in broad circum-continental terraces (bp—tp–at). The dashed line (sl) indicates sea-level, here idealized as unchanging. The sediments marked ‘e’ (which form seaside cliffs following the diastrophic movement) are the same as those marked ‘d’, once erosion and deposition have built the marine terraces. The evolutionary response to diastrophism is, in the first place, a matter of real estate— when broad marine terraces and inland seas are available, rapid diversification takes place (expansive evolution); when they vanish, intense competition leads to spasms of extinction (restrictive evolution)
Still, Chamberlin’s voice was present, especially in Lull’s discussion of the origin of chordates. This he began by affirming a “thesis”: that the distinction between vertebrates and invertebrates “is largely dynamic, for the former are principally motor types, the latter largely quiescent, sluggish forms” (Lull 1918, 114). Since vertebrates evolved from invertebrates, the challenge was to explain the origin of the “motor type” from a quiescent starting point. This led Lull (following Chamberlin) to consider the effects of the secular environment on modes of life. He began by historicizing the thesis. The invertebrate, he explained, is “the product of static waters… where an effortless existence, carried hither and yon by wave and tide, would not remove it from [its preferred] environment” (116). The vertebrate, by contrast, “is the outcome of dynamic or flowing terrestrial waters which enforced swimming powers as the only means of resisting eviction from the realm” (emphasis in original). These are causal (indeed, historical) claims. It was stagnant water that caused invertebrates to adopt quiescent life styles. Likewise, it was flowing water that caused the evolution of the notochord as a direct response to the demands of the environment. (Lull did not say whether natural selection was implicated in the origin of the notochord or whether the effect was more mechanical. Anyway, the evolution of the structure was “stimulated” by the change in physical conditions.)
To illustrate “the means whereby the evolution [of chordates] was initated,” Lull again followed Chamberlin. In an essay published in 1900, Chamberlin had considered “the peculiar habit of a stream-borne lamprey, Petromyzon, which adheres to the bottom by its suctorial mouth and allows its body to undulate in the pulsating current” (Lull 1918, 116). This undulation is passive; it is like a flag flapping in the wind. However, when the lamprey needs to maintain its position in the current, it “reproduces in the active voice the motions imparted to it in the passive voice by the stream itself” (117). “Such motion, consisting as it does of a series of reversed curves, requires segmented muscles on either side [of the body], along which alternating waves of contraction may pass.” It also requires an axial stiffening— a notochord or spinal column— to resist the longitudinal compression. And all to enable the animal to navigate a regime of flowing waters.*
[* Bizarrely, it was imagined that only a regime of rapidly flowing water could supply the stimulus needed to evolve the power of rapid locomotion. Lull admitted that “some marine worm-like organisms swim by a wriggling movement”— a seeming precursor to the active swimming of chordates (Lull 1918, 118). But then he declared that “there is in the sea little incentive to enforce [the] rapid perfection [of this locomotive power], such as dynamic waters would produce. Hence the assumption that the chordates are the outcome of terrestrial waters.”]
Petromyzon marinus, from Edward Donovan’s The Natural History of British Fishes (1803)
Lull now out-Chamberlin-ed the master himself, tying the whole drama back to diastrophism. According to Lull,
Geology records a great diastrophic movement toward the close of the Proterozoic, the so-called Grand Canyon revolution, partial evidence for which may be seen in the 8,000 to 12,000 feet of sediments, more or less conglomeratic, which were swept from mountains to the eastward and accumulated in the southern Appalachian region during… Lower Cambrian time. This great upheaval changed the face of nature in many regions and quickened the static terrestrial waters to rapid and widespread movement over all the uplifted lands. Such invertebrate stocks as could neither cling to the bottom nor stem the quickening current were swept to the encircling sea and lost to the limnobiotic fauna; such as could [stem the current] remained to people the fluviatile realm with creature of a markedly higher sort. (Lull 1918, 118–119)
As far as Lull could tell, this was consistent with the evidence from the fossil record. He concluded “that the place of chordate origin was the flowing land waters, to which may be added as the impelling cause a diastrophic movement which quickened the drainage” (Lull 1918, 119). This key “crisis” in the history of life was accordingly “the direct outcome of earth movement without the intervention of the climatic factor.”
In other cases climate was decisive. The origin of reptiles, for example, was put down to a diastrophic movement that brought with it a wave of aridity, “making the return [of amphibious proto-reptiles] to natal waters difficult until many forms were forced to abandon it altogether” (Lull 1918, 125). Likewise, the origin of warm blood was ascribed to “[a] series of earth movements that was to culminate in the Appalachian revolution,” which brought in their train increased aridity and continental glaciation (127). This put land-dwelling reptiles in a bind, since aridity “places a premium upon traveling powers, [and] especially upon speed,” owing to a general scarcity of food and an intensified “strife between the pursuer and pursued.” The conflict was resolved by the evolution of higher body temperatures permitting more rapid metabolisms. And thus were born the mammals and birds.
Lull’s model of Anchisaurus, an early sauropodomorph dinosaur from the Jurassic Period (Lull 1915). Lull speculated that dinosaurs, which sprang from a similar “reptilian stock” as birds, had higher body temperatures than their reptilian ancestors. Theropod bipedalism he attributed to aridity— witness “the present existence of several bipedal lizards… in our own [American] Southwest” (Lull 1918, 130). By contrast, it was humid conditions that “tempted certain of the increasingly large Theropoda to forsake the strenuous life of a carnivore for the slothful ease of an amphibious herbivore.”
“The pulse of life” is not an impressive piece of reasoning. It is, rather, a mostly flat-footed attempt to locate the causes of evolutionary events in the heavings of the earth and their climatic corollaries. Still, Lull’s contemporaries apparently had a higher opinion of it. Barrell referenced it several times in his “Rhythms and the measurement of geologic time,” and even included a paragraph-length description of Lull’s discussion of chordate evolution. For his part, Roy Moodie, reviewing the book in Science, remarked that “[no] one could speak with more knowledge of the facts as to the ‘pulse of life’ than Professor Lull,” and offered that the chapter might have been called “The philosophy of paleontology” (Moodie 1919, 140–141).
Did Simpson read it? Probably. He was a voracious reader, and the chapter also appeared, in abbreviated form, in Lull’s Organic Evolution. Yet Simpson certainly read a different meditation on the link between diastrophism, climate, and evolution, which was published in the Annals of the New York Academy of Sciences in 1915. This was William Diller Matthew’s paper— later reprinted as a monograph— “Climate and evolution.”
Climate and Evolution
W. D. Matthew was an outstanding paleontologist. The son of George Frederic Matthew— an accomplished amateur geologist and paleontologist— the younger Matthew studied geology and paleontology at Columbia University, eventually coming under the sway of H. F. Osborn. He subsequently joined the Department of Vertebrate Paleontology, working under Osborn’s supervision (which is to say, working on whatever Osborn told him to). In this, his situation paralleled that of Osborn’s other star pupil, William King Gregory, who would go on become a leading functional morphologist.
“Climate and evolution” grew out of Matthew’s early work at the American Museum. Under Osborn’s direction, Matthew had taken an interest in a range of topics at the intersection of geology and paleontology. The earliest had to do with biostratigraphy and correlation; Osborn was particularly concerned to refute the idea, put forward by the Argentinian scientist Florentino Ameghino, that Patagonia was the historical center of mammalian evolution (Rainger 1996). Matthew took the led on this. Later, his work expanded into a more general exploration of the origin and migration of animal groups, especially mammals. Matthew’s first publications embodied a number of Osborn’s ideas, like the notion that a southern continent once connected South America and Australia, providing a highway for the migration of marsupials and certain “lower animals and plants” (Matthew 1906, 357). However, “while Osborn offered intriguing ideas and was interested in a range of questions concerning… geographical distribution, it was Matthew who did firsthand research and delved much further into [the topic]” (Rainger 1996, 192). This led him, by 1902, to the ideas of Thomas Chrowder Chamberlin.
A map labeled “Hypothetical continental outlines— Post-Cretaceous,” drawn up for the fossil mammal hall at the AMNH and reproduced in Matthew (1906)
“Climate and evolution” began with backstory. In 1902, Matthew had been invited to give a talk to the Linnaean Society on the subject of “climate and evolution.” The subject was new to him; in his previous work on biogeography he had not been very concerned with matters of climatic change. Yet as he understood his assignment, it was straightfoward. It was to apply “to vertebrate paleontology [the] theories in regard to geological history which had been brought forward by Chamberlin a year or two previously” (Matthew 1915, 3). These theories “are to-day widely known and are year-by-year gaining a wider acceptance.” So, while his remarks of the subject remained provisional, Matthew saw value in “submitting for general consideration” the conclusions he had reached during the thirteen years that had elapsed since the Linnaean Society presentation.
Matthew did not provide a detailed summary of Chamberlin’s geological ideas. Perhaps he regarded these as so widely known in 1915 that no big fuss was needed. Still, he observed that they “differ from the older prevailing concept of geologic climatic conditions chiefly in that they involve an alteration of climates through the course of geologic time from extremes of warm, moist tropical and uniform, to extremes of cold, arid zonal climates” (Matthew 1939, 3–4).
The former are the results of prolonged base-level erosion and the overflow of large continental areas by shallow seas. The latter are the results of the re-adjustments needed to bring the continents once more into isostatic balance, involving the general lifting of the continents, especially of their borders, the expansion of the continental areas to their utmost limits and the renewal of rapid erosion. (Matthew 1939, 4)
“These alternations of conditions,” he continued, “are marked by alternations of the prevalent type of formation in the geological series. Periods of baseleveling leave behind “widespread deposits of limestones” and in their waning stages, coal formations. “The periods of uplift are marked by thick barren formations, often red in color, … [and] finally culminate in great extension of glaciers from boreal and high mountain areas” (Matthew 1939, 4). For more detail, Matthew directed readers to Chamberlin and Salisbury’s Geology (see Part 1 of this essay, Appendix 2). The purpose of the present work, he reiterated, was “to indicate [the] application [of these ideas] to the evolution of land vertebrates.”
William Diller Matthew during his brief stint as director of the University of California Museum of Paleontology. Matthew died in 1930 at age 59, just three years after taking the appointment
Matthew began his essay, quite usefully, with a “thesis” statement comprising five points. It ran as follows:
Secular climatic change has been an important factor in the evolution of land vertebrates and the principal known cause of their present distribution.
The principal lines of migration in later geological epochs have been radial from Holarctic centers of dispersal.
The geographic changes required to explain the present distribution of land vertebrates are not extensive and for the most part do not affect the permanence of the oceans as defined by the continental shelf.
The theories of alternations of moist and uniform with arid and zonal climates, as elaborated by Chamberlin, are in exact accord with the course of evolution of land vertebrates, when interpreted with due allowance for the more probable gaps in the record.
The numerous hypothetical land bridges in temperate tropical and southern regions, connecting continents now separated by deep oceans, which have been advocated by various authors, are improbable and unnecessary to explain geographic distributions. On the contrary, the known facts point distinctly to a general permanency of continental outlines during the later epochs of geologic time, provided that due allowance be made for the known or probable gaps in our knowledge. (Matthew 1939, 3)
The term “Holarctic” named a region comprising the land masses of Eurasia and North America. This was the cradle of evolution, in Matthew’s view, because it happened to be stitched together into a great land mass (with the seams buried in the sediments of the marine shelf). The southern masses, by contrast, were tapering spindles of land without connections to one another. This made the southern continents “unfavorably situated for the evolution and dispersal of dominant races.”
But why did the current distribution of land matter so much? To begin, Matthew affirmed the permanence of the ocean basins— for him, land and sea were not interchangeable, as they had been for many in the nineteenth century. These scientists thought land and sea traded places because continents are covered in strata that were deposited underwater. Yet Matthew, following Chamberlin, explained the same deposits by appealing to great cycles of flooding and emergence, now creating shallow seas, now vast aprons of exposed rock. This had major consequences for the postulation of land bridges. If new continents do not sometimes rise from the sea or fall into it, then land bridges are limited to continental shelves exposed during periods of land emergence. (The Bering Land Bridge, over which Matthew supposed early humans to have walked, is a good example.) It followed that any southern lineage with aspirations to world domination would have to make its way north before it could access the centers of radial distribution.
Two figures from Climate and Evolution. Left: “Zoölogical regions on north polar projection,” with shelf areas unshaded. According to Matthew, “This map represents the true relations of land and water in the northern hemisphere far more correctly than does the usual Mercator projection.“ The map also supplies a base chart on which a whole series of illustrations in the work are modeled; for an example, see below. Right: “The southern continents with south polar projection,” and deeper water indicated by progressively denser cross-hatching
But this would be a tall task, Matthew thought, because superimposed upon the diastrophic cycles were climatic ones, bringing cold and aridity following extremes of emergence, and uniform warmth following extremes of flooding. Especially important were the periods of emergence, since these would be periods of expansive evolution— periods of waxing for the terrestrial fauna. During this waxing, terrestrial life would succeed to the extent that it could adapt to cold, arid, and variable conditions of the sort first encountered near the poles. So, Matthew reasoned, the most northerly and southerly faunas would enjoy the advantage of an evolutionary head-start. They would be “more progressive,” in his words, and this would enable them to overtake their competitors as they spread toward more equatorial regions.*
[* Why were those animals adapted to cold, arid and variable conditions “more progressive” than those adapted to warm and uniform conditions? The answer is that the former conditions, “while favoring the spread and wide distribution of races, would be unfavorable to abundance of life and the ease with which animals could obtain a living. The animals subjected to them must maintain themselves against the inclemency of nature, the scarcity of food, the variations of temperature, as well as against the competition of rivals and the attacks of enemies.” By contrast, “[in] the moist tropical climatic phase, animals would find food abundant and temperature relatively constant… We should expect, therefore, to find in the land life adapted to the arid climatic phase a greater activity and higher development of life” (Matthew 1939, 7).]
But again, why was it for the north to conquer the world? At this point two geographic facts came into play. The first was that the lands of the north are just bigger than those of the south; so insofar as evolution is facilitated by large interconnected areas (as the model of expansive evolution has it), then the Holarctic can be expected to produce a greater number of progressive lineages than its southern counterpart. The second was that the northern lands were more favorably situated for the dispersal of lineages in virtue of their interconnectedness. So both in terms of the supply of “dominant races” and their dispersal, the Holarctic held an advantage over what might be termed the “Holantarctic.”*
[* If you’re detecting racist overtones in this discussion, you’re not wrong. Matthew’s racial assumptions were plainly expressed in the text. “It will not be questioned,” he wrote, “that the higher races of man are adapted to a cool-temperate climate, and to an environment rather of open grassy plains than of dense moist forests. In such conditions they reach their highest physical, mental and social attainments” (Matthew 1939, 43). Like his boss, Matthew was a eugenicist. Jonathan Spiro has described him as one of “the elite of the eugenic establishment” and noted his membership in the Galton Society (Spiro 2009, 306). And his followers sometimes veered into flagrant racism; so, when Karl Schmidt sought to apply Matthew’s ideas to the distribution of human races, he declared: “The superiority of the Eurasian races to isolated native races elsewhere is pitifully clear in the extermination of the Tasmanians, the decimation of the South Sea Islanders by the white man’s diseases, and in the relict populations of kinky haired blacks in the Malayan Islands” (Schmidt 1943, 245).]
Matthew’s map of the “Dispersal and distribution of the principal races of man.” This is the first dispersal map Matthew included in the text, probably because it depicted one of his central contentions very clearly— to those who shared his social prejudices. This was the location of the most “advanced” forms near the point of original dispersal (here, Eurasia)
That was the general argument. In the body of the work, Matthew marshaled evidence in support of the picture. Not all the evidence fit. The new world Edentates, including the sloths and anteaters, probably originated in tropical South America, he surmised. Likewise, the distribution of hystriocomorph rodents (including the capybara) “necessarily involves the idea that the [South American] continent has been the most important center of their later development and dispersal” (Matthew 1939, 64). (This left open the question of where the group originated; anyway, Matthew supposed that these forms reached South America “in the Oligocene by over-sea raft transportation.”) But these were exceptions that proved the rule. And the rule was northern origin. In Matthew’s view, land vertebrates radiated outward in successive waves from northern “centers of dispersal.” The most advanced forms were expected nearest the centers of dispersal— that is, in the northern hemisphere. The more conservative forms were expected near the periphery. The conclusion applied to all vertebrate groups, including “mankind.” And this reinforced the notion, which social prejudice had suggested, that “the progressive refrigeration of the polar regions was the dominant cause of evolutionary progress” (Matthew 1939, 55).
The dominance of Holarctic dispersion was the major theme of “Climate and evolution.” It involved, as an assumption, the permanence of ocean basins, which implied as a corollary the unreality of most supposed land bridges. And it invoked, as the immediate cause of successive waves of southward migration, climatic oscillations associated with diastrophic pulses. Of course, Chamberlin was pleased with it:
This important paper is notable for the emphasis it lays on climatic variations and physical changes as agencies dominating organic evolution, for its adherence to the essential permanency of the continents, and for its unhesitating rejection of oceanic eversions and of extravagant bridge-building across abysmal depths for mere convenience in explaining biological distribution… He appeals to the powerful influence of climatic oscillations running back over the whole history of vertebrate life and beyond, whose verity is being constantly supported afresh by new evidence, and to the co-operative influence of physical changes connected with periodic diastrophism and denudation which have constantly varied the environment of life. (Chamberlin 1915, 477)
But Chamberlin was not alone. In the years following 1915, his influence radiated far and wide (Rainger 1996; Livingstone 2012). It continued to radiate until the plate tectonics revolution brought about its rapid obsolescence in the 1970s (Morrone 2022). But never mind that. For present purposes, only one channel of influence matters, the one that flowed from Matthew through his successor as the assistant curator of vertebrate paleontology at the American Museum, George Gaylord Simpson.
Periodic Diastrophism AFTER 1930: Some conclusions
From their first field trip together, Simpson revered Matthew. In a posthumous remembrance, he marveled at his “amazing store of information & extensive knowledge of fossil mammals, which I am sure no one else has ever equaled” (Simpson 1986, 200). Fittingly, Matthew promoted Simpson as his replacement at the American Museum when he departed for California in 1927 (Lapotre 2000). Reflecting on their relationship many years later, Simpson recalled having “absorbed every word he spoke… [and] read every word he had written” (quoted in Rainger 1996, 213).
But this isn’t really about Simpson— not anymore. I take the previous sections to have established what I set out to establish; that “Simpson’s support for periodic diastrophism was over-determined, at least in the early going.” Both Matthew and Lull were enthusiastic proponents of periodic diastrophism. So it isn’t surprising that Simpson expressed support for it, especially before he had expended any real energy trying to figure out whether it was true.
Another photograph from the Bone Cabin Quarry expedition (1899), showing Matthew (right) and Lull (left), as well as Peter Kaisen, excavating the Brontosaurus specimen
But where does this leave us? Simpson’s apparent support for diastrophism gave me pause because Simpson struck me as an unlikely diastrophist. But in fact he was a very likely diastrophist. Not only his mentors, but also the store he set by organism-environment interactions gave the diastrophic theory an innate attraction. Which brings us back to square one. Lloyd Henbest, writing in 1952, called periodic diastrophism “the prevailing concept” in American geology. Yours truly, writing in late February, found this difficult to believe.
But hold on, because we aren’t quite back at square one. At the end of Part 2 I wrote that, as far as I can tell, the popularity of periodic diastrophism crested in the 1910s, before declining, gradually, in the 1920s. I wrote this because, by 1930, significant doubts had crept in about whether diastrophic pulses really were global in scope. Bailey Willis declared, way back in 1910, that “[the] periods of diastrophic activity have been relatively short, and as regards the whole surface of the earth in general not contemporaneous” (259). Charles Schuchert observed in 1929 that the “Cambrian, Ordovician, and Cretaceous ‘periods,’ as now delimited, are surely not in harmony with the teachings of [periodic] diastrophism” (339). Francis Shepard argued in 1923 that “diastrophism has been continuous” and concluded that “there is little reason to believe in periodic diastrophism” (599, 613). This adds up to more than a mote of worry. Still, the last author went on to say that “[a]mong American geologists the theory of periodic diastrophism is generally accepted… Most authors of text books and many other geologists speak of the end of the Paleozoic and the end of the Cretaceous as [times] of great disturbance all over the world.”
At this point it will be useful to draw a distinction I didn’t draw in February. Back then I took periodic diastrophism to say that globally synchronous movements provide the basis for dividing geohistory into periods and the geological column into systems. That was Thomas Chamberlin’s position, as well as E. O. Ulrich’s. It was the position Schuchert had in mind when he said that the Cambrian, Ordovician and Cretaceous systems “are surely not in harmony with the teachings of diastrophism.” Now grant that Schuchert is right: diastrophism can’t be used to divide time into periods. Still, it remained possible to claim that globally synchronous movements provide the basis for dividing geohistory into eras— or groups of periods— and the column into erathems. This was the position many seem to have held after 1930, and indeed 1940. It relied on a distinction between minor and major diastrophic crises— “disturbances” and “revolutions” in Schuchert’s (1918) terminology. Of these, only the revolutions were presumed to be truly worldwide events. They were the culmination of grand diastrophic crescendoes built from an escalating series of diastrophic pulses.
A figure from Schuchert (1918), titled “Diagram showing the times and probably extent of the more or less marked climatic changes in the geologic history of North America, and of its elevations into chains of mountains.” (Compare to the diagram from Lull (1918), above; the most striking difference is that the Cambrian and Ordovician are missing, replaced with a string of periods including Ulrich’s Ozarkian and Canadian.) Here, most geological periods are held to be associated with “revolutions” as opposed to “disturbances.” But the largest revolutions are those that separate the great eras
The view did not escape all criticism. Shepard (1923) dared “To question the theory of periodic diastrophism,” and in Chamberlin’s Journal of Geology no less.* Winifred Goldring told of a program “held in the Paleontological Society of Washington [in 1938]” that “brought out information that cast doubt on the prevailing concepts of periodic diastrophism” (Goldring 1952, 298). Ten years later, the president of the Geological Society of America used his platform to express doubts about the synchronicity of mountain-building episodes. These were later published as Gilluly (1949). The same year Henbest’s symposium took place at the GSA. In the symposium, Simpson reported finding “little support… for the theory of simultaneous, world-wide physical and biological climaxes at the period and era boundaries.” If I’m right, the more important of these conclusions was the lack of evidence for simultaneous climaxes at the boundaries between eras.
[* He waited, however, until Chamberlin resigned as editor (1922).]
Still, Simpson’s remarks were made in 1949, and around that time it was probably defensible to say that a somewhat flexible version of periodic diastrophism was indeed “the prevailing concept in [America] geology” (Henbest 1952, 299). Chamberlin’s planetesimal hypothesis was dead (Brush 1978). His contractionism was dead (Oreskes 1999). The stronger forms of diastrophism had failed to square with the facts of the stratigraphic record. And yet the somewhat surprising conclusion of this essay is that, despite all this, a commitment to diastrophic periodicity kept its grip on the American geological imagination. I’m pretty surprised to be typing this. My suspicion a month ago was that it couldn’t possibly be the case. But perhaps it isn’t surprising that an idea as attractive and elastic as periodic diastrophism would have a long career. Bolstered by Chamberlin’s prestige, and the prestige of his acolytes, it became a prism through which many came to see the stratigraphic record. Sedimentation, erosion, mountain-building, faunal change: all could be understood in terms of rhythmic oscillations of different magnitudes, variously joined into composite rhythms. In this respect periodic diastrophism was less a hypothesis about the world as a way of thinking about the nature of the stratigraphic record itself.*
[* Here I should soften something I said in Part 2. At the end of that essay I wrote that, by 1930, “periodic diastrophism took its place among other important ideas whose scope of application remained to be precisely determined.” This is true; once the limitations of the theory had been recognized, it was no longer possible to regard it as a kind of master key for the stratigraphic record. But this didn’t make it just another idea. It remained an idea that shaped how people approached the record, even as they marshaled evidence relevant to evaluating the theory (Shepard 1923). This, as its critics recognized, made it especially tricky to refute.]
I end this essay having arrived at an unexpected place, knowing there’s more to say. I wish I knew more about Schuchert and Willis. The criticisms offered by Shepard and Gilluly deserve a look. It may even be worth asking whether a commitment to periodic diastrophism played a role in shaping American attitudes toward continental drift. Looking into these things is bound to be interesting. But I suspect that, for now, I’ve said enough.
References
Barrell, J. 1917. Rhythms and the measurements of geologic time. Bulletin of the Geological Society of America 28:794–904.
Brush, S. 1978. A geologist among astronomers: the rise and fall of the Chamberlin-Moulton cosmogony, part 2. Journal of the History of Astronomy 9:77–104.
Chamberlin, T.C. 1898a. The ulterior basis of time divisions and the classification of geologic history. The Journal of Geology 6:449–462.
Chamberlin, T. C. 1898b. A systematic source of evolution of provincial faunas. The Journal of Geology 6:597–608.
Chamberlin, T. C. 1900. On the habitat of the early vertebrates. The Journal of Geology 8:400–412.
Chamberlin, T. C. 1915. Reviewed work: Climate and Evolution by W. D. Matthew. The Journal of Geology 23:477–478.
Gilluly, J. 1949. Distribution of mountain-building in geologic time. GSA Bulletin 60:561–590.
Goldring, W. 1952. Foreword. Journal of Paleontology 26:298.
Henbest, L. G. 1952. Significance of evolutionary explosions for diastrophic division of earth history— introduction to the symposium. Journal of Paleontology 26:299–318.
Lapotre, L. F. 2000. George Gaylord Simpson: Paleontologist and Evolutionist. New York: Columbia University Press.
Livingstone, D. 2012. Changing climate, human evolution, and the revival of environmental determinism. Bulletin of the History of Medicine 86:564–595.
Lull, R. S. 1915. Triassic Life of the Connecticut Valley. Hartford: State Geological and Natural History Survey,
Lull, R. S. 1918. The pulse of life. In R. S. Lull (ed.) The Evolution of the Earth and its Inhabitants: A Series of Lecture Delivered before the Yale Chapter of the Sigma Xi during the Academic Year 1916–1917, 109–146. New Have: Yale University Press.
Lull, R. S. 1920. Organic Evolution. New York: The Macmillan Company.
Matthew, W. D. 1906. Hypothetical outline of the continents in Tertiary times. Bulletin of the American Museum of Natural History 22:353–383.
Matthew, W. D. 1915. Climate and evolution. Annals of the New York Academy of Sciences 24:171–318.
Matthew, W. D. 1939. Climate and Evolution. New York: Special Publications of the New York Academy of Sciences.
Moodie, R. L. 1919. Reviewed work: The Evolution of the Earth and Its Inhabitants by Joseph Barrell, Charles Schuchert, Lorande Loss Woodruff, Richard Swan Lull, Ellsworth Huntington. Science 50:140–141.
Morrone, J. 2024. Matthew’s (1915) climate and evolution, the “New York School of Biogeography,” and the rise and fall of “Holarcticism.” History and Philosophy of the Life Sciences 44:https://doi.org/10.1007/s40656-022-00500-3.
Oreskes, N. 1999. The Rejection of Continental Drift: Theory and Method in American Earth Science. Oxford: Oxford University Press.
Rainger, R. 1996. An Agenda for Antiquity: Henry Fairfield Osborn and Vertebrate Paleontology at the American Museum of Natural History, 1890-1935. Tuscaloosa: University of Alabama Press.
Schmidt, K. P. 1943. Corollary and commentary for ‘Climate and evolution’. American Midland Naturalist 30:241–253.
Schuchert, C. 1918. The earth’s changing surface and climate during geologic time. In R. S. Lull (ed.) The Evolution of the Earth and its Inhabitants: A Series of Lecture Delivered before the Yale Chapter of the Sigma Xi during the Academic Year 1916–1917, 45–81. New Have: Yale University Press.
Schuchert, C. 1929. Chamberlin’s philosophy of correlation. The Journal of Geology 37:328–340.
Shepard, F. P. 1923. To question the theory of periodic diastrophism. The Journal of Geology 31:599–613.
Simpson, G. G. 1944. Tempo and Mode in Evolution. New York: Columbia University Press.
Simpson, G. G. 1952. Periodicity in vertebrate evolution. The Journal of Paleontology 26:359–370.
Simpson, G. G. 1986. G. G. Simpson’s recollections of W. D. Matthew. PALAIOS 1:200–204.
Willis, B. 1910. Principles of paleogeography. Science 31:241–260.