* This is Part 2 of a three-part installment of “Problematica.” It explores the popularity of Thomas Chamberlin’s theory of periodic diastrophism in the first half of the twentieth century: just how big a deal was it, anyway? The whole essay was inspired by a few sentences in Tempo and Mode in Evolution (here is the link to Part 1, which explores the origin of the diastrophic theory). Problematica is written by Max Dresow…
Thomas Chamberlin’s theory of periodic diastrophism was a big deal. But just how big a deal was it? Was it really the “prevailing idea” in American geology in 1950— the kind of thing an introductory student could expect to encounter early in their geological education? And if so, was it usually presented, not as one possibility among many, but as the currently-accepted best way of looking at things? That was the contention of some mid-twentieth century geologists writing before the consolidation of plate tectonic theory (e.g., Henbest 1952). But as long as I’ve known about this claim I’ve doubted it. Few people think, for example, that it was adherence to Chamberlin’s geotheory that prevented American geologists from getting behind continental drift (cf. Wood 1985).* But if periodic diastrophism really was the prevailing idea in American geology, this would be an irresistible narrative.
[* Except, perhaps, in this sense. It is often noted that American geologists had a particular commitment to continental permanence as a matter of geotheory. Usually, this is traced to the influence of James Dwight Dana, who regarded continental and oceanic crust as non-interchangeable and fixed in place (Oreskes 1999). But the permanence and fixity of the continents is just as much a feature of Chamberlin’s system as of Dana’s; so if Chamberlin succeeded Dana as America’s leading geotheorist, the popularity of fixity should be ascribed, at least in part, to Chamberlin’s influence.]
Thomas Chamberlin during his time as the president of the University of Wisconsin (1887–1892)
Of course, research moves faster than pedagogy, so we need to distinguish two claims: the first, that periodic diastrophism supplied a general framework for geological inquiry in 1950, and the second, that it played a key role in geological pedagogy in 1950. The second claim is more plausible than the first. But what inspired this essay was evidence that diastrophism continued to find favor with researchers as late as the 1940s. As George Simpson wrote in Tempo and Mode in Evolution: “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). That’s just what the theory of periodic diastrophism predicted, and, as I said in the first part of this essay, it’s frankly shocking that these words were tapped out on Simpson’s typewriter.
In the second part of the essay, which you’re now reading, I try to come to grips with the popularity of periodic diastrophism between 1910 and 1930. I first discuss E. O. Ulrich, who carried Thomas Chamberlin’s ideas on diastrophism back and forth across the country, and ultimately used them to carry out a sweeping revision of the Paleozoic series: his very own “diastrophic revolution.” Then I discuss some other geologists influenced by Chamberlin, including Joseph Barrell, Charles Schuchert, Bailey Willis, Amadeus Grabau, and Chamberlin’s son, Rollin. Later, in Part 3, I will return to Simpson and the question that motivated this essay: how popular was the diastrophic theory after 1930?
E. O. Ulrich’s diastrophic revolution
E. O. Ulrich was, by all accounts, a difficult man: headstrong, touchy, and prone to bouts of professional belligerence. He never saw a fight he didn’t like, at least when it came to defending his own, often highly controversial, stratigraphic ideas. And yet he was widely regarded as an outstanding paleontologist and stratigrapher; someone whose discoveries put him “into line with [Roderick] Murchison, [Adam] Sedgwick and [Charles] Lapworth” (Ruedemann 1946, 270). These men had established five of the six periods of Paleozoic time: the Cambrian (Sedgwick), Ordovician (Lapworth), Silurian (Murchison), Devonian (Murchison and Sedgwick), and Permian (Murchison). Ulrich’s ambition was to add two periods of his own: the Ozarkian— a block of time to follow the Cambrian— and the Canadian— a block of time to follow the Ozarkian.* And all based on a stratigraphic model built upon the foundation of periodic diastrophism.
[* Actually, this isn’t quite the whole story. In addition to intercalating two periods between the Cambrian and Ordovician— these four systems together comprising the “Eopaleozoic”— Ulrich pushed to recognize two new systems in a subsequent “Neopaleozoic,” the Waverlyan and Tennessean. These systems were held to follow the Silurian and Devonian in succession, bringing the total number of Paleozoic systems to eight. (That is, after the Pennsylvanian had been placed in the Mesozoic and the Permian eliminated entirely!) But the Waverly and Tennessee “groups” were already recognized before Ulrich came on the scene. With the Ozarkian and Canadian things were different. These were Ulrich’s creations, and his great ambition was to see the Ozarkian in particular accepted as a real system.]
Edward Oscar Ulrich (1857–1944)
Ulrich was largely self-educated. Hailing from Covington, Kentucky, he was one of the founders of the “Cincinnati School” of paleontology that flourished near the end of the nineteenth century (Caster 1982). (Covington is just across the river from Cincinnati.) In his early twenties he met Charles Schuchert— later a bigshot geologist at Yale— and the two soon developed a close friendship. Along with their joint enthusiasm for fossils, the men indulged the fashion for spiritualism that was then sweeping the country, and even participated in some amateur productions of Gilbert and Sullivan operas (Ruedemann 1946). Their friendship would later fracture under the weight of Ulrich’s irascibility, or perhaps his insecurity. But this was not before Schuchert had played a key role in securing Ulrich’s appointment with the U.S. Geological Survey in 1897— an appointment that had been threatened by Ulrich’s reputation for cantankerousness.
The pinnacle of Ulrich’s career was undoubtedly 1911. This was the year a “paper,” totalling no fewer than 399 pages, appeared in the Bulletin of the Geological Society of America. Titled “Revision of the Paleozoic Systems,” it was the culmination of a decade spent amid the ridges and valleys of Appalachia and the undulating plains of the Midwest. During this time, Ulrich had become an undisputed expert on the Paleozoic rocks of the eastern half of the country. But that was not all he had done. In addition, he had developed a philosophy of stratigraphic correlation deeply indebted to Chamberlin’s writings on periodic diastrophism. As Ulrich wrote in an abstract to his paper (published as a free-standing piece in Science): “The proposed [revision] is based primarily on crustal movements, diastrophism, the succession of which is determined by the faunal evidence.” With Chamberlin as a guide, Ulrich intended to rewrite the geological column of North America, and with it, the very geological time scale itself.
The “Revision” is not a triumphant piece of writing. Convoluted and repetitive, it includes several discussions of the same concepts and criteria, to say nothing of duplicated criticisms. (It seems the peripatetic Ulrich had little time for editing.) Still, these repetitions underscore what Ulrich took to be the significance of the work: not merely the definition of two new geological systems, but the articulation of a new mode of stratigraphic practice based on diastrophic criteria. His goal was first to establish that his stratigraphic methods were beyond reproach, and second, to show what could be obtained through their application— a fundamental revision of the Paleozloic series.
A figure from the “Revision” showing incursions of the Atlantic and Pacific oceans over geological time. Notice the “oscillatory character” of the incursions and the total draining of the continents at period boundaries. This draining would leave a major erosional surface or unconformity, which Ulrich used (following Chamberlin) to define the base of a system. Notice also the two new systems intercalated between the Cambrian and Ordovician— the Ozarkian and Canadian
Ulrich began with a critique of fossil evidence. The point wasn’t to disparage fossils; Ulrich was a paleontologist after all. It was just to say that fossils aren’t an all-sufficient guide to stratigraphic correlation, especially for “minor stratigraphic units of distinct basins” (Ulrich 1911, 291). Fossils needed to be used in conjunction with other forms of evidence to ensure reliable correlations. Physical and structural evidence put fossils in context, enabling geologists to more reliably interpret occurrence patterns and avoid illicit inferences. Fossils, for their part, help geologists locate physical surfaces, whose position fixes the boundaries of important stratigraphic units.
The most important kind of surfaces in Ulrich’s geology were erosional surfaces, or unconformities. These were produced by oscillations in the level of the land and sea, here creating space for deposition, there exposing sediments to erosion. When the sea retreated, sedimentary deposits that were formerly underwater would be gnawed down by wind, rain, and running water, with sediments accumulating in ocean basins. However, with the return of the sea, shallow water deposition would recommence, smothering the surface in sediment. All that would remain at this point was an unconformity, which might be practically invisible if the lithology of the over- and underlying sediments was the same. Still, the surface would reflect an interval of time erased from the stratigraphic record. And, more importantly, it would record the action of a process operating on regional or even global scales, which could then be used to carve the geological column at its joints.
The last was Chamberlin’s insight, and Ulrich was happy to credit him as its author. “In my opinion,” Ulrich wrote, “a rhythmic relationship connects nearly all diastrophic movements… [which] may be arranged into cycles and these again into grand cycles, the whole arrangement probably corresponding in units to the divisions of an ideal classification of geologic time” (Ulrich 1911, 399). Diastrophism “affords a true basis for intercontinental correlation of not only the grander cycles but also of their subordinate stages.” But how, exactly? That is where Ulrich’s subordinate assumptions came in. For Ulrich, the natural units of the geological column were packages of sediment bounded by unconformities. These unconformities could be “traced” around the world, at least those bounding the very largest units (systems). But there were erosional surfaces bounding smaller units too, and these were produced by the same processes operating on smaller scales. Every sedimentary unit, regardless of scale, began with an episode of submergence and deposition and ended with one of emergence and erosion. Deposition took place within basins produced by diastrophic processes, like the downwarping of the continental crust. The basins were not, as a rule, interconnected; Ulrich imagined each basin to have its own history of submergence and emergence (allowing it to receive sediments by flooding or lose them by erosion), and its own faunal assemblages derived from the ocean basins.* This meant that the history of each basin, while under diastrophic control as far as sedimentation went, was to some extent decoupled from the history of the rest.
[* This was the source of much friction between Ulrich and his colleagues. Most of these preferred a model of large epicontinental seas: “long enduring, often broad and deep interoceanic waterways,” containing much variation in physical conditions (Ulrich 1911, 534). But in Ulrich’s view, stratigraphic evidence favored a model of discrete basins separated by buckled-up portions of crust (“barriers”), alternately filling and emptying. In Ulrich’s words, these basins were “limited in extent and subject to frequent oscillations and withdrawals [of the sea],” with “geographic changes in nearly contemporaneous fossil faunas [due] less to local physical conditions than to original peculiarities of the faunas of the oceanic basins from which the different continental seas happened at the time to draw their organic supplies” (312).]
Left: map of North America showing overlapping (successive) invasions from the Arctic, Atlantic, Gulf of Mexico and Pacific sides. Notice the pattern of deposition this suggests; not one of shifting facies in a stable, interconnected seaway, but one of successive deposition of lithologically uniform units in shallow, oscillating basins. Upper right: a “sketch map of southeastern North America” showing Appalachian troughs and “principal lines along which stratigraphic overlaps are common” (Ulrich 1911, 293) An overlap, for Ulrich, “suggests preceding sea withdrawal and cessation of marine deposition in the areas thereby emerged” (329). Lower right: deposition in a sedimentary basin, showing three stratigraphic units of consistent lithology and characteristic “morphology” (thick in the middle and pinched out on the sides)
For Ulrich, the duration of the hiatus represented by the unconformity determined the rank of the unit: whether it was a system, series, or stage, say. His method was “to divide the stratigraphic sequence at the first plane beneath the introduction of a new fauna or beneath a marked faunal change that exhibits evidence of diastrophic movements” (Ulrich 1911, 581). If the plane marked “a great faunal break,” so long as “the compared faunas invaded from the same oceanic basin,” then Ulrich regarded it as the beginning of a new system. He did this because, in Chamberlin’s model, the largest faunal breaks are expected to be associated with the largest diastrophic pulses, the ones that divide earth’s history into “periodic phases of worldwide prevalence” (Chamberlin 1898, 449).
One such break occurred just above the Cambrian deposits in the Appalachian Valley. Here, resting unconformably on Cambrian rocks, were thousands of feet of dolomitic limestone containing scant fossil remains: the Ozarkian System. It was named after its type location in the Missouri Ozarks, which, although thinner than the Appalachian succession, was “more fossiliferous and, … in an epitomized way, more complete” (Ulrich 1911, 28). Still, it was in Appalachia that the rocks staked their claim to system-status, mounting from the Bellefonte dolomites in Alabama to the carbonates of Pennsylvania. Then, another break. And above it, a second new system, the Canadian, including all rocks younger than the Ozarkian dolomites and older than “the first sandstone and limestone of the Saint Peter series in northern Arkansas” (647). This included a succession of limestones and shales especially well-developed in Newfoundland— ergo, the “Canadian System.” Unlike the Ozarkian, the Canadian had no clearly demonstrable base. But it had thickness; one measured section in Bellefonte, Pennsylvania comprised over 4,000 feet of fossiliferous limestones. No Canadian or Ozarkian rocks were known from outside North America, although the identification of these rocks as systems implied that they must exist elsewhere.
A figure showing (A) the “fluctuation and oscillation in average relief of median Areas of North America with respect to Sealevel,” and (B) “relative vertical Displacement of the Strandline [former shoreline] in successive Periods with respect to an assumed average Sealevel.” In this figure, the troughs of the relief and displacement curves correspond to unconformities, and the peaks to maximum floodings. The figure also shows a temporal asymmetry between Eo- and Neopaleozoic time, when submergent conditions predominated, and Meso- and Cenozoic times, when emergent conditions predominated
The Ozarkian, in particular, was Ulrich’s baby. According to Lael Bradshaw, he defended this system “with an intensity that far exceeded his other efforts to establish his geologic ideas” (Bradshaw 1989, 164). It was his play for scientific immortality, his attempt to inscribe his name on the very base of the Phanerozoic rock column. But it did not succeed. Today, geologists place all the rocks assigned to the Ozarkian and Canadian “Systems” into either the upper Cambrian or lower Ordovician strata. The names, meanwhile, have been abandoned (Weiss and Yochelson 1995).
Ulrich survives in geological memory as a cautionary tale. If people know anything about him it’s that he ignored facies relationships, which explain how distinct lithological features and fossil assemblages can sometimes be contemporaneous (Brett et al. 2007).* Because he ignored facies, Ulrich tended to multiply stratigraphic units beyond necessity. For him, it was almost a matter of logic that each package of sediment represented its own time interval. So he massively extended the Phanerozoic column by carving out new systems and series that were, in fact, already represented in the time scale.
[* This was related to his disbelief in large continental seaways, and his penchant to think in terms of shallow basins dominated by relatively uniform depositional environments (see, e.g., Ulrich 1911, 317–319.]
Still, this should not lead us to underestimate Ulrich’s impact on American stratigraphy, which was considerable. As an apostle of Chamberlin, Ulrich was a dominant presence, a force to be reckoned with. His colleague Rudolph Ruedemann called him “an outstanding scientist without any peer in his field” and others paid him respect by avoiding direct confrontation. But even at his peak he was never the undisputed leader of American stratigraphy. Always there was resistance to his ideas, always controversy. And his influence waned after the publication of the “Revision.” By the 1920s and certainly by the 1930s Ulrich’s stratigraphy was on its way out (Bradshaw 1989). Facies was the word of the day, and Amadeus Grabau ascendant. Ulrich bristled and eventually raged at this, but it was to no avail. Even America’s most forceful stratigrapher was powerless to turn back the clock.
Radiating Influence
I have devoted an entire section to Ulrich because he was the perfect stratigraphic ambassador of Chamberlin’s ideas, the person who translated periodic diastrophism into a sweeping revision of the Paleozoic time scale. But as Dunbar and Rogers note in their Principles of Stratigraphy, “practically all the outstanding American geologists” of Ulrich’s generation were influenced by Chamberlin: among them, Charles Schuchert, Bailey Willis, Joseph Barrell, and “that king of the fakers” (to quote Ulrich) Amadeus Grabau (Dunbar and Rogers 1959, 303). Then there was Rollin Chamberlin, Thomas’s son and successor at the University of Chicago. Like his father, Rollin was convinced of “the concept of the world-wide periodicity of diastrophism as the ultimate basis of correlation” (Pettijohn 1970, 94). This put him in the company of E. O. Ulrich as a loyal acolyte of the elder Chamberlin. But unlike Ulrich (and like his father), Rollin was no boots-on-the-ground stratigrapher. Instead, he was a structural geologist interested primarily in the origin of folded mountains. He also studied glaciers, and devoted some of this time to testing “ideas developed by the elder Chamberlin as a result of his studies of glaciers in north Greenland” (Pettijohn 1970, 96).*
[* Rollin was, of course, a nepo baby. But he was also an accomplished scientist, eventually gaining election to the National Academy of Sciences. And he climbed mountains, making a total of sixty-three ascents before health concerns forced him to retire. These included summits of Pico de Orizaba, Mont Blanc and the Matterhorn.]
Rollin Chamberlin (1881–1948) and a photograph taken in the Cariboo Mountains of British Columbia during an expedition with Allen Carpe (1927). Together the two men climbed Mount Sir John Abbott (Kiwa Peak), one of Chamberlin’s sixty-three alpine ascents
The younger Chamberlin taught at the University of Chicago for 35 years beginning in 1912. This was perhaps the main conduit for the elder Chamberlin’s ideas, and it’s curious that the symposium I mentioned in Part 1 of this essay was only convened in 1949, the year after Rollin’s death. Still, Thomas Chamberlin’s influence traveled along many grooves radiating both east and west from his kingdom in the Windy City. An especially important one cut through New Haven, Connecticut, where Schuchert took up a position in the Yale geology department beginning in 1904. Around the same time a brilliant young geologist, Joseph Barrell, arrived to fill a chair in structural geology created specifically for him. Barrell would die from infection just sixteen years later, prompting Thomas Chamberlin to lament his passing: “We [geologists] had come to look upon him as one of the most promising leaders in the deeper problems of earth science” (quoted in Schuchert 1925). William Morris Davis went ever further, calling Barrell’s death “a truly overwhelming disaster for American geology. We place him foremost in our science.”
According to Schuchert’s recollection, Joseph Barrell was “5 feet 10.5 inches in height… with a full head of wavy light brown hair” (Schuchert 1925, 4). He “was pale and spare of build, and yet of great muscular strength— the ‘strong man’ of his class at Lehigh.” More to the point, he was brilliant. In the words of Herbert Gregory: “His intellectual power was so obvious and so continuously displayed that twenty years of intimacy has left on me an impression of a mind rather than of a man.” Schuchert was more worldly, noting that Barrell belonged to the “blue-eyed Nordic type”— the kind of remark that takes on a more sinister cast when it’s remembered that it was written at the height of the eugenics craze in North America.
Joseph Barrell (1869–1919), who died of pneumonia and spinal meningitis at 49
Barrell’s brilliance was on full display in his most celebrated paper, “Rhythms and the measurement of geologic time” (1917). The paper— which ran to an Ulrichian 170 pages— began with a bit of purple prose that established the author’s indebtedness to Chamberlin:
Nature vibrates with rhythms, climatic and diastrophic, those finding stratigraphic expression ranging in period from the rapid oscillation of surface waters, recorded in ripple-mark, to those long-deferred stirrings of the deep imprisoned titans which have divided earth history into periods and eras. (Barrell 1917, 746)
Of these rhythms, the most important for the determination of geologic time were the diastrophic ones. These must ultimately “be measured in terms of the smaller, and the smaller… in terms of years. Sedimentation is controlled by them, and the stratigraphic series constitutes a record, written on tablets of stone, of these lesser and greater waves of change which have pulsed through geologic time.”
Barrell’s paper was aptly titled. It was about “the measurement of geologic time,” and included a long discussion of “measurements based on radioactive decay”— a subject that was then just ten years old. However, “the viewpoint of the paper [was] geological,” and before Barrell turned to these newfangled concerns, he spent three sections considering variations in the rate of geological processes over time (Barrell 1917, 747). For example, he observed that the “later Tertiary and Quaternary” together formed a “great period of revolution,” which is to say, an interval of mountain building (768). This interval came at the end of a long process of falling sea levels (relative to continents), which Barrell thought could have amounted to as much as 500 meters since the Paleozoic. Now, because rates of denudation (erosion) were known to increase with relief, the present high relief of the continents meant that rates of continental denudation could be “ten to fifteen, or even twenty, times the mean for all earth history” (749). It followed that attempts to estimate the magnitude of time based on extrapolating present rates of denudation were bound to be in error. To arrive at sound estimates of the duration of geological time, it was necessary to take into account variations in geological conditions, and this meant coming to grips with “the markedly cyclic or rhythmic nature of geologic activities, both in denudation and in deposition, and the acceleration of these conditions at the present time” (789).
Today, Barrell’s paper is mostly remember for a remarkable diagram titled “Sedimentary Record made by harmonic Oscillations in Baselevel.” This was the diagram that established Barrell, in the eyes of a later commenter, as the first geologist “to understand the relationships between sedimentation, preservation, and accomodation [the space available for sedimentary accumulation]” (Miall 2015, 11–12). Barrell sets the stage by noting that “[the] making of a sedimentary series is conditioned on an oscillating but progressive rise in baselevel” (Barrell 1917, 789). (“Baselevel” is an abstract surface corresponding to the wave base or river flood level— it is the lowest level to which running water can flow, and so the lower limit of an erosional process.) A rise in baselevel ensures that space is available for sedimentation. This is accomplished by downwarping, Barrell thinks (although sea-level rise will also do the trick). Now, because the depression of land tends to be discontinuous, sedimentation occurs in rhythmic pulses separated by periods of land emergence and scour. It follows that sedimentation is not a continuous process even during period of net crustal depression “but represents an irregularly rhythmic alternation of fill and scour with a balance in favor of the fill” (748). Barrell is not saying that sedimentation is never continuous. He thinks that if you trace the deposits of a continental shelf far enough from shore, they “must begin to show a continuous record” (793). But closer to shore the sedimentary record is interrupted by a great many gaps, some small, some large. To steal a line from Derek Ager (1973), the sedimentary record is “more gap than record,” at least in those environments that have contributed most to the Phanerozoic rock column.
Barrell’s figure, “Sedimentary Record made by harmonic Oscillations in Baselevel,” with color codings for ease of interpretation. Here, blue shading represents intervals of time in which sedimentary accumulation is possible, whereas pink shading represents intervals of time erased by erosion (and represented by disconformities, D, in the columnar section). The total amount of time represented by sedimentary deposits is represented by black bars in the “bar code” (top of figure). I’ve also included a pie chart to represent the amount of time recorded by the entire columnar section (left).
Like Barrell’s observations on denudation, the processes represented in this figure have implications for estimates of the magnitude of geological time. As Barrell observes, “A fundamental conception connected with composite rhythms is that a long time interval may be represented by a short columnar section, and yet the individual beds may be deposited rapidly” (Barrell 1917, 798). This means it is illicit to extrapolate observed rates of deposition to estimate “the time of accumulation of [a] whole formation,” since this will tend to undersell the amount of time represented by the formation
Barrell’s diagram illustrates this picture and draws out its implications. Specifically, it shows how a combination of “rhythms”— small and large, fast and slow— conspires with continuous downwarping (giving a long-term rise in baselevel) to produce the sedimentary series at a single location. In the diagram, time flows from left to right. The curve A-A describes the long-term rise of baselevel, increasing the space available for sedimentary accumulation.* The curves B-B and C-C, which are here pictured as a composite curve containing both major (B-B) and minor (C-C) oscillations, depict, on the one hand, diastrophic oscillations separating the “smaller divisions of time,” and on the other, the summation of smaller oscillations including climate cycles. The diastrophic oscillations are responsible for the breaks in sedimentation or “disconformities,” marked with lines in the stratigraphic column at the left of the figure. The “crenulations” associated with climate cycles and other minor rhythms are associated with smaller breaks in sedimentation, which Barrell terms “diastems.” Both kinds of gaps are pictured in the “bar code” at the top of the figure. The larger gaps represent disconformities, the smaller ones diastems. Black bars represent intervals of time recorded by sedimentation, which add up to much less time than those “recorded” by gaps.
[* Or perhaps it would be better to say rejuvenating the space available for sedimentation at regular intervals, since the space available for sedimentary accumulation is not a simple function of downwarping.]
All this goes well beyond anything Chamberlin ever wrote. Yet it is anchored in a basically Chamberlin-ian view of the stratigraphic record, in which diastrophism supplies a basic control on sedimentary accumulation. Diastrophism is not the only control, and it’s difficult to imagine Barrell saying, as Chamberlin once did, that in comparison with diastrophism “the elements of denudation and deposition are essentially trivial” (Chamberlin 1909, 693). Still, Chamberlin’s voice pulses through Barrell’s work:
It is clear that epochs of diastrophism are more or less closely correlated in widely different regions. Changes in sealevel are necessarily felt over the whole earth, increasing or decreasing by relativity the mean height of the lands. But beside this the lands themselves are periodically broadly warped and, more locally, mountain growth takes place. In so far as the relief of the land is simultaneously modified, the stages of erosion cycles in different regions tend to be correlated and the mean rate of denudation for broad regions and even for the whole earth may vary in the same direction. (Barrell 1917, 756)
Then there was Schuchert. An invertebrate paleontologist by trade (he coined the term “paleobiology”) and a leader in the study of historical geography (“paleogeography”), Schuchert had fallen out with his old friend Ulrich over stratigraphic matters, including his adoption of the facies concept. Yet he continued to admire Chamberlin, and even contributed a paper to a memorial volume on “Chamberlin’s philosophy of correlation” (Schuchert 1929). There he recounted the basic features of Chamberlin’s philosophy, noting that “of all Chamberlin’s teachings, no other is more widely used than his philosophy of correlation.”
The cyclic phenomena in the evolution of the earth are now nearly everywhere in Europe and America an accepted fact in geology, and the various writings of Chamberlin setting forth the manifestations of diastrophism have made the working of this principle all the plainer. (Schuchert 1929, 338)
A signed painting of Charles Schuchert (1858–1942), and Schuchert’s hand-drawn paleogeographic map of North American (late Cretaceous) showing marine incursions
The principle of cyclicity was especially important to the new field of paleogeography. Schuchert recounts that he began drawing paleogeographic maps in 1903, “and more especially since 1910 he [i.e., Schuchert himself] has been using, as the basis for the delimitation of periods and eras, the cyclic phenomena of diastrophism as defined by Chamberlin, plus the results of organic evolution” (Schuchert 1929, 338). He observed, however, that as time went on and knowledge became “more detailed and exact,” it was “made plainer that our accepted periods are not all in harmony with the cyclic truism, partly because there are minor cycles within the major diastrophic ones, not all of which appear to be explainable by continental creep and by water displacement due to the accumulating sediments” (338–339).
Some of the minor cycles are surely produced by body deformations [as Chamberlin held]… and some are of such wide transgression as to call for oceanic subsidence and a changed sea-level amounting to some hundreds of feet (climatic control was absent at these times). On the other hand, it now also appears that the withdrawal of the oceanic waters from the continents at the close of the period cycles is not always as complete as the writer formerly held. [Ditto for Ulrich.] (Schuchert 1929, 339)
Some continents even show “stratigraphic records completely bridging the supposed breaks between certain periods, making it necessary to be very cautious in deciding just where the line of separation shall be drawn” (Schuchert 1929, 339). Anyway, Schuchert observed that the breaks between the major eras still line up with the grand diastrophic cycles— a kind of consolation prize for the diastrophic theory.
Schuchert’s friend Bailey Willis was likewise influenced by Chamberlin. “The periodicity of diastrophism is the fundamental fact of geographic history,” he thundered at the 1909 meeting of the American Association for the Advancement of Science. “[All] changes in the inorganic as in the organic are conditioned by that periodicity, and all such changes are therefore themselves periodic… It follows logically from the preceding that the initial cause of change, diastrophism, is necessarily the ultimate basis of all correlation” (Willis 1910, 255). And yet the periods of diastrophism, Willis thought, have not, as a rule, been contemporaneous the world over. For Willis, “the great ocean basins” were “distinct dynamic provinces,” each with its own history of diastrophic disturbance. Moreover, it is only the continental masses adjacent to the affected basin that are disturbed during an interval of diastrophic activity. It follows that “folding and unconformity… are frequently not contemporaneous even in one and the same dynamic province,” and certainly not between provinces (259). As Willis put it, “major cycles of world-wide conditions are constituted by coincidence of regional conditions” (247–248).
Still, while the different groups of diastrophic phenomena are “very unequal in scope, character, and value [for correlation],” yet “all other phenomena are dependent and sequential” (Willis 1910, 257). “Diastrophism sets the stage and marks off the acts of the earth drama.” Natural change is, in the last analysis, periodic.
Bailey Willis (1857–1949) and Amadeus Grabau (1870–1946). Willis’s relationship with Chamberlin has sometimes been misunderstood, as, for example, when Mott Greene observed that his 1909 remarks betrayed only a hesitant acceptance of the diastrophic theory (Greene 1982). In fact, this is based on a misreading of some key passages, whereas Willis’s correspondence reveals an opinion of Chamberlin bordering on reverence (see, e.g., Newman 1995). Indeed, when Chamberlin died, Willis placed him beside Aristotle, Copernicus, Galileo, Newton, and Darwin as one of history’s “great original thinkers” (Willis 1929a)
The final figure to mention is Amadeus Grabau, the champion of the facies concept in American stratigraphy. Born in Chamberlin’s home state of Wisconsin, Grabau rose rapidly in the geological profession and at thirty-one secured a professorship at Columbia University. There he authored two influential textbooks, including Principles of Stratigraphy (1913), which devoted several pages to a (very positive) treatment of “correlation by diastrophism.” This is perhaps not so surprising. Grabau’s book sprawled to more than 1,200 pages, after all, and Chamberlin was then a dominant figure. Still, it is interesting that both Ulrich and his great rival accepted correlation by diastrophism essentially as Chamberlin envisioned it. So wide was Thomas Chrowder Chamberlin’s influence on American geology in the early twentieth century.*
[* Grabau is a fascinating character. German by descent, he split from his wife— the writer and immigration advocate Mary Antin— in 1919 due to her pro-German sentiments. At which point he relocated to Peking University (Beijing) and became a beloved teacher and mentor, earning the title “Father of Chinese Geology.” While in China he developed a comprehensive view of the stratigraphic record based on the idea that the cyclic phenomena recorded in major packages of strata resulted from slow oscillations in sea level (Grabau 1940). These were ultimately driven by the swelling and contraction of the sea bottom, which is to say, by diastrophism in the ocean basins.]
Periodic diastrophism in 1930
In his essay on Chamberlin’s philosophy of correlation, Schuchert asked whether “[Chamberlin’s] principles [have] become everyday working ones among the students of historical geology?” (Schuchert 1929, 338). In answering, he distinguished between the European scene, where “very little direct use is… made of them,” and the American one, where “the story is quite different.” Here, “Willis, Weller, Ulrich, Bassler, Raymond, Schuchert, and others have been using to good advantage the principles of diastrophism, and through their many students this knowledge has grown into wide acceptance.”* In American geology prior to 1930, Thomas Chamberlin was a dominant presence, his ideas a lingua franca for otherwise very different geologists.
[* Weller, Bassler, and Raymond were Marvin Weller, R. S. Bassler, and Percy Raymond.]
None of this is very surprising, especially considering that Chamberlin was alive and active during this period. The real question— the question that motivated this essay— is whether periodic diastrophism remained popular into the 1930s and even the 1940s. It’s a question for Part 3; but to put a bow on the present discussion, let me say that, as far as I can tell, Chamberlin’s influence crested in the decade following 1910. Already by the 1920s it was in decline— and while the decline was gradual, still the salad days had come to an end (Greene 1982). Then, in the 1930s, Chamberlin and Moulton’s planetesimal hypothesis came in for criticism. This had been Chamberlin’s major focus in the decades preceding his death, but by 1935— and certainly by 1940— it was moribund (Brush 1978). Periodic diastrophism was not thus killed; that theory had preceded the planetesimal hypothesis and could survive without its coordinating assumptions. But as Schuchert (1929) had observed, the more daring versions of the diastrophic theory were, by then, also in difficulty:
The Cambrian, Ordovician, and Cretaceous “periods,” as now delimited, are surely not in harmony with the teachings of diastrophism, and the Silurian, Devonian, Mississippian, Permian, and Triassic appear to manifest minor diastrophic cycles in their marine oscillations in this or that continent. (Schuchert 1929, 339)
Schuchert was generous to allow that Chamberlin had “always recognized and [given] considerable thought to the minor diastrophic manifestations superposed on the larger diastrophic cycles” (Schuchert 1929, 339). But the drift of his remarks was clear. As geologists had acquired increasingly detailed knowledge of the sedimentary record, the utility of Chamberlin’s model had diminished. Nature might vibrate with rhythms, but the rhythms were not as coordinated as Chamberlin had hoped. With this realization, periodic diastrophism took its place among other important ideas whose scope of application remained to be precisely determined (Willis 1929b).
Find a link to Part 3 here when it is available…
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