Popular Science Monthly/Volume 84/February 1914/Early Geological Work of Thomas Nuttall

From Wikisource
Jump to navigation Jump to search



WHEN, in England about a century ago, earth-study was made a modern science through William Smith's famous geological discoveries that the relative age and natural sequence of rock-layers were susceptible of accurate determination by means of the contained organic remains, America very early, and from a wholly unexpected quarter, furnished important aid in support of the newly established principles. The circumstances were long since all but forgotten. In the few casual references made to them in latter years either their significance was misunderstood or familiarity with the attendant conditions was entirely wanting. As the first successful application of modern geologic principles in the New World the episode must ever remain of greatest historic interest.

Singularly, this primal American effort to correlate by their faunal contents geologic formation widely separated geographically was not made in that portion of our continent which was most accessible and where it was most natural to expect it—that is, along the well-settled Atlantic border—but it was in the then remotest section of the upper Mississippi valley. First fruits of research and observation were obtained in a region which was then perfect wilderness, but which now forms part of the great and populous state of Iowa. Moreover, these remarkable observations were made within a decade of the time when the novel method was originally announced in England. They antedated by fifteen years Samuel Morton's similar effort on the Tertiaries of our Atlantic coast commonly regarded as the maiden attempt in America along these lines. By two decades they were in advance of the first work of that pioneer American paleontologist, Lardner Vanuxem. They anticipated by a full generation the famous investigations of Thomas Conrad and James Hall in New York. Indeed, they were the means of actually and correctly interpreting the true position and biotic relations of the Carbonic rocks of the continental interior a half century before their geologic age was otherwise generally admitted. The Mississippian limestones, as the rocks are now called, remain to-day as compact and as sharply delimited a sequence of geologic terranes as they appealed when first recognized in that memorable summer of the year 1809.

This successful use in America of faunal criteria for purposes of solving problems of geologic correlation and of identifying geological formations was the first real ray of modern light to penetrate the graphic darkness shrouding the New World. The happy application of these criteria was due directly to the keen scientific perception and peculiar reasoning of one who was never known as a geologist at all, but who was raised to fame through a wholly different channel of scientific activity. The name of this truly remarkable personage was Thomas Nuttall, botanist.

Nuttall's extensive travels in America were undertaken chiefly in the interests of his monumental works on North American plants and of his valuable contributions to American ornithology. On his first great trip, after traversing the southern shore of Lake Erie, and coasting by canoe Lakes Huron and Michigan, he entered Green bay, and, following that famous all-water route to the west which the Indians had used from time immemorial, ascended Fox river to the short portage to the Wisconsin river, down which latter stream he floated to its month, near Prairie du Chien, thence down the Mississippi river to St. Louis. Subsequent trips took him far up the Missouri and Arkansas rivers.

On his Mississippi venture besides garnering great quantities of interesting plants and taking voluminous notes on the birds, he appears to have made extensive collections of the fossils which he found throughout his path abundantly scattered through the limestones which in high cliffs bordered both sides of the great stream. In the course of his explanations of the geologic features of the region through which he passed Nuttall naively notes that he is "fully satisfied that almost every fossil shell figured and described in the 'Petrif acta Derbiensia' of Martin was to be found throughout the great calcareous platform of secondary rocks exposed in the eastern Mississippi valley." Thus by means of fossils he parallels these limestones of the Mississippi river with the mountain limestone of the Pennine range in Derbyshire, England, to which, several years later, Conybeare gave the title of Carboniferous.

Along the Mississippi river, as we now know, Nuttall really encountered little else than rocks of Early Carbonic age, so that his identifications of the fossils were doubtless, with very few exceptions, correct. Moreover, at this date and for some time afterward, the lower portion of the exposed stratigraphic sections, it must be remembered, was entirely undifferentiated, the great sequence of older beds which were subsequently separated from one another being jumbled together under the title of Transition group. It was not until more than a quarter of a century later that out of them, in Britain, Murchison and Sedgwick established the Cambrian, Silurian and Devonian systems.

Another important geologic correlation is to be credited to Nuttall. On his journey up the Missouri river, in 1810, which he undertook with John Bradbury, a Scotch naturalist, he reached the Mandan villages on the upper reaches of that stream. He makes especial mention of the Omaha village situated below the mouth of the Big Sioux river. A short distance upstream from the last mentioned point he examined strata which, by means of their fossils presumably, he refers to the Chalk division of the Floetz, or Secondary, rocks of northern France and southern England. This is the earliest definite recognition of beds of Cretacic age in America. It preceded by a decade and a half the separation, by John Finch, of the newer Secondary rocks from the Tertiary section in the Atlantic states, and Lardner Vanuxem's and Samuel Morton's references of the same deposits to the Cretaceous age. Thus also was another great succession of one of our main geologic periods discovered in a then remote part of our continent years before it was recognized in the East.

At the mouth of the Big Sioux river Nuttall fell in with an old trapper who described to him the great falls which blocked navigation at a distance of 100 miles up that stream, and who told him of the famous Indian pipestone quarries beyond.

The analogy established by Nuttall between the general Carbonic section of Iowa and the upper Mississippi valley and that of northern England was one of the important geologic discoveries in America. Its great significance was pointed out by Owen a couple of decades later. Its historical value grows with the advancing years. In the final recognition of a standard Carbonic section for this continent the sequence displayed in the Mississippi basin must prevail, since it is now generally conceded that the Appalachian succession of strata can never be considered as the typical development.

So conspicuously botanical in character are Nuttall's services to science that one can but wonder under what circumstances he could have obtained his keen insight into matters geological. Elias Durand said of him immediately after his death that "No other explorer of the botany of North America has personally made more discoveries; no writer on American plants, except perhaps Asa Gray, has described more new genera and species." Lists of his published memoirs and papers quite generally omit all reference to his recorded geological observations, probably because their importance could hardly be fully appreciated by writers in other fields of science. In the present connection our main interest centers on the transplanting so early to the interior of the American continent of Williams Smith's novel ideas concerning fossils. Brief reference to some of the early events in Nuttall's life seem to offer a clue.

Nuttall was born in Yorkshire, England, in the mountain limestone belt, and near the scene of Martin's famous labors on the Carbonic fossils of Derbyshire. He was early apprenticed to the printer's trade and after a few years removed to London. There he followed his trade until, at the age of 22, he set out for America, in 1808. He appears to have been a printer of the Benjamin Franklin order, since while engaged at his trade he became proficient in the knowledge of the sciences, Greek and Latin, and kindred subjects. During the period of six or seven years that he was in London he appears to have made the acquaintance of a number of the scientific men of the day. At least it is probable that at this time he acquired some familiarity with Smith's discoveries, which were at that date attracting wide attention from English scientists. It is also quite possible that Nuttall gained much of his scientific information through setting up the types for those very memoirs which have since become geologic classics. It is not unlikely also that he even met Smith, since the latter is known to have been often in London at that time, and to have taken up his permanent residence there several years before the printer-naturalist left his native country.

At any rate, Nuttall had been in America scarcely a year before he was putting his geological knowledge to test. His familiarity with Martin's "Petrifacta Derbiensia" and Smith's principles clearly indicates that he must certainly have acquired his information at least several years previous. Then, too, his acquaintance with that pioneer American geologist, William McClure, for twenty years president of the American Philosophical Society at this period, should not escape notice. Two other papers, partly geological in nature but chiefly mineralogical in character, on the rocks and minerals of Hoboken, and of Sparta, New Jersey, and the many keen observations on the rocks recorded in his journal of a trip from Philadelphia to Pittsburgh attest his unusual intimacy with matters in geology.

Notwithstanding the fact that the brief memoir which Thomas Nuttall published on Iowa-land and the contiguous regions was the only one which he seems ever to have printed on strictly geological subjects so important are the principles set forth for the first time in this single, simple, short contribution to the literature of American terranal correlation that it places its author in the front rank among pioneer geologists, not only of Iowa, but of our country. Although one of the foremost botanists of his day, and an ornithologist of world-wide reputation his great service in first pointing out by method and by means the fundamental concepts of modern historical geology in America should not be forgotten.