THOMAS NUTTALL 185 



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 scien- 

 tific 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 coast- 

 ing 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 in- 

 teresting 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, Eng- 

 land, to which, several years later, Com^beare gave the title of Carbon- 

 iferous. 



Along the Mississippi river, as we now know, Nuttall really en- 

 countered little else than rocks of Early Carbonic age, so that his iden- 

 tifications 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 



VOL. LXXXIV. — 13. 



