|EARLY GEOLOGICAL WORK OF THOMAS NUTTALL|
DES MOINES, IA.
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 strati-