APPENDIX TO THE REPORT OF THE SECRETARY. Gl 



A very extraordinary feature of these rocks is the occurrence of silici- 

 fled forests which are found in situ not only at one liorizon but at a great 

 number of horizons throughout a great part of the whole series. Fos- 

 sil leaves found associated with the silicified forests near the middle of 

 the series indicate the prevalence of a flora very closely related to that 

 of the present time. They belong, according to Professor Lesquereux, 

 to late Miocene or early Pliocene times. 



Among the many points of interest in the way of flowed volcanic 

 rocks was the discovery and examination of extensive deposits of obsid- 

 ian. In one locality upwards of 600 feet of obsidian strata occur, much 

 of which is solid glass ; banded, sphernlitic, and brecciated varieties are 

 interbedded with the more solid layers. A very extensive collection of 

 these and other volcanic rocks was made. 



ifo workable beds of coal have been found within the park area, nor 

 have any deposits of the i^recious metals been discovered. 



To Br. A. C. Peale and Mr. J. E. Mushbach was assigned the special 

 investigation of the hot springs and geysers. Owing to the lateness of 

 the season when the park was reached, and the early storms in Septem- 

 ber, there was comparatively little time for work. About two months 

 were spent by them in mapping and investigating the sjirings in the 

 Shoshone Basin, Upper and Lower Fire-Hole Basins, Red Mountain 

 Basin, Gibbon's Fork Basin, the Mammoth Hot Springs, and the Mud 

 Springs localities of the Yellowstone River. 



Over 1,500 temperatures were recorded, and about 2,500 springs were 

 mapped and notes taken for their description. Special attention was 

 paid to the geysers and notes of their times of eruption and the heights 

 reached by them were taken. 



Two of the geyser basins were almost unknown before and had never 

 been described. The Gibbon's Fork Basin presented many features of 

 interest, among which were the numerous varieties of the siliceous de- 

 posits, many of them probably new to science. Water from important 

 springs of the principal localities was brought in for future analysis. 

 Notes were taken for mapping the different groups of springs on a large 

 scale, so that hereafter they may enable the tourist to identify the in- 

 dividual springs. Many new geysers were discovered and new points of 

 interest in relation to the old ones obtained. 



Large collections of specimens were made and brought east. 



The notes of this division of the survey being largely statistical, the 

 complete results of the work cannot be detailed until they are thor- 

 oughly worked up. 



The following is a summary, by Mr. O. St. John, of the geological 

 work prosecuted in the field assigned to the Wind River division : 



The region explored comprises a triangular area extending along tlie 

 forty-third parallel from Salt River to the Wind River Valley, a distance 

 of about 100 miles. The boundaries on either side converge, uniting 

 near the parallel 13° 45'. It thus includes about half of the Wind River 



