LETTER TO THE SECRETARY. XV 



t 



subjected to considerable folding and displacements in the different por- 

 tions of the district. 



One of the most interesting discoveries was that of the presence of 

 fish-remains in the Lower Carboniferous. Several forms were found, 

 identical with or closely allied to Keokuk species of the genera Cladodus, 

 Petalodus, Anthiodus, and Helodus. 



In the upper basin of Snake River, Tertiary lacustrine beds occur. 

 These are probably the equivalents of the lake-beds of Dr. Hayden. 



The Teton Range was examined, and found to be a gigantic monoclinal 

 ridge, with a metamorphic *and granitic nucleus, which forms a lofty 

 exceedingly rugged, jagged crest, extending in a north and south direc- 

 tion three-fourths the length of the range, culminating in Mount Hayden. 



In Jackson's Basin, east of the Teton Range, a vast accumulation of 

 morainal matter was noted. Along the west side of the basin extensive 

 morainal accumulations occur, which have been cut into beautiful ter- 

 races by Snake River. 



Calcareous tufa, indicating the presence of springs, was found at the 

 mouth of Salt River, in a small basin east of Lincoln Valley, &c. None 

 of these, however, are comparable with the enormous spring deposits 

 met with at the northeastern foot of the Wind River Mountains, in the 

 upper portion of the Wind River Valley, which were hastily examined 

 late in the season. 



The geological notes given above present only the salient features of 

 the season's work. 



PALEONTOLOGY. 



The necessity of a careful examination of the various geological for- 

 mations in the field, and a review by a practical paleontologist of the 

 various districts that have from year to year been surveyed by the dif- 

 ferent geologists of this and other surveys, has been long felt. Such a 

 work, indeed, was imperatively necessary before a consistent and com- 

 prehensive classification of the formations could be established. This 

 duty was assigned to Dr. C. A. White, the paleontologist of this survey, 

 and he took the field at the beginning of the past season and continued 

 his labors until its close. The special duty with which he was charged 

 was to pursue such lines of travel as would enable him to make critical 

 examination of the geological formations in succession as they are exposed 

 to view on both sides of the Rocky Mountain chain, and also on both 

 sides of the Uintah chain ; to collect and study the fossds of these forma- 

 tions in such detail as to settle, as far as possible, the questions of the 

 natural and proper vertical limits of the formations, their geographical 

 range, their correlation with each other, and to define the paleontologi- 

 cal characteristics of each. 



He has pursued his researches with such success during the past sea- 

 son as to demonstrate the necessity of continuing this class of investi- 

 gations by various lines of travel across what is generally known as the 



