AMERICAN GEOLOGY DECADE OF 1850-1859. 



457 



The first report, known under the title of Geological Reconnaissance 

 of Tennessee, was presented to the general assembly in 1855, and pub- 

 lished in 1856. It was given up largely to a somewhat popular treatise 

 on the economic geology of the State, with much interesting stratigraph- 

 ical matter. 



He discussed the occurrence of the ores of iron, copper, lead, zinc, 

 and even gold and silver, and included also a brief chapter on Alu- 

 minum or the Metal from Clay. "Stone coal'" and the marbles 

 received a share of attention, as well as various minor minerals. From 

 a strictly geological standpoint the matter given in chapters 5 and 6 — 

 the closing chapters of the report — was of greatest importance. Here 

 he dwelt on the general geological structure of the State and gave the 

 now well-known Cumberland section, reproduced with the original 

 legend in tig. 61, and also an ideal cross section illustrating the geolog- 

 ical structure of East Tennessee. He pointed out the striking paral- 

 lelism of the valleys and ridges and the occasional vertical position of 

 the beds, as well as the frequent repetition of the same series of beds, 

 due to folding 1 and faulting. 



N. W. 



Fig. 61. — Section from the Cumberland, 8 miles north of Jasper, to the Eastern base of Lookout 

 Mountain. I After James M. Safford.) 

 (Length of section, 20 miles: vertical scale, about five thousand feet to the inch.) 

 A and C, High edges, respectively, of the Cumberland and Walden's ridge, overlooking Sequatchee 

 Valley, represented by the depression between. D, Narrow valley of the Tennessee River; the section 

 crosses a few miles above Kelly's Ferry. E, Portion of the Walden's ridge and Raccoon range cut off 

 by the river, etc. L, Lookout Mountain. Depression between E and L, Valley of Lookout Creek. 



The unbroken lines represent the formations as they actually occur. The broken lines indicate 

 the elevation of the folds, and the amount of matter removed by denudation. B, Summit of the 

 restored Sequatchee fold. I, I, Converging lines indicating a section of the supposed fissure or rent. 

 F, Summit of another smaller fold. 



He grouped the rocks under fourteen formations, extending from 

 the mica-slate group of metamorphic rocks of Azoic age to the Allu- 

 vial, post-Tertiary series. The much discussed and still enigmatical 

 Ocoee conglomerates were included in his semimetamorphic series at 

 the top of the Azoic. Troost, it will be remembered, put them at the 

 base of his Cambrian. 



The importance of fossils for purposes of correlation was at this 

 time distinctly recognized. 



Every formation has, in great part, its own species of fossils. Most of those found 

 in one do not occur in any other. Upon this fact depends the great utility of fossils. 

 They furnish, when known well enough to be recognized, unmistakable evidence of 

 the geological position, and hence the general character of the formation in which 

 they occur. 



