82 GEOLOGICAL SURVEY OF THE TEEEITORIES. 



The evidence is clear that ever since the cessation of the more power- 

 ful volcanic forces these springs have acted as the escape-pipes, but 

 have continued to decline down to the present time, and will do so in the 

 future, until they cease entirely. The charts accompanying this report 

 will enable. the reader to form a clear conception of the position and 

 number of the most important springs in this basin, but an equal num- 

 ber of the dead and dying have been omitted. We may therefore con- 

 clude that the present system of hot springs and geysers is only a feebler 

 manifestation of those remarkable internal forces of the earth, which 

 were so wonderfully intensified during the periods of volcanic activity, 

 that they really present for our study a miniature form of volcanism. 

 Even at the present time there are connected with them manifesta- 

 tions of internal heat and earthquake phenomena which are well 

 worthy of attention. While we were encamped on the northeast side 

 of the lake, near Steamboat Point, on the night of the 20th of July, 

 we experienced several severe shocks of an earthquake, and these 

 were felt by two other parties, fifteen to twenty-five miles distant, 

 on different sides of the lake. We were informed b}^ mountain -men 

 that these earthquake shocks are not uncommon, and at some sea- 

 sons of the year very severe, and this fact is given by the Indians 

 as the reason why they seldom or never visit that portion of the 

 country. I have no doubt that if this part of the country should 

 ever be settled and careful observations made, it will be found that 

 earthquake shocks are of very common occurrence. 



Our trail passed over the rim of the basin on the south side of Mount 

 Washburn, and the lowest point was 8,774 feet. In crossing this divide or 

 rim, I saw, on the north side, some of the somber argillaceous sandstones 

 that contain the deciduous leaves between Gardiner's Eiver and Tower 

 Creek, After passing the " divide" we descended the almost vertical sides 

 of the rim into the valley of Cascade Creek, at the level of 7,787 feet, or 

 about 1,000 feet below the " divide." Our trail was a tortuous one, to 

 avoid the fallen timber and the dense groves of pine. The country im- 

 mediately around the creek looked like a beautiful meadow at this sea- 

 son of the year, (July 25,) covered with grass and flowers. Cascade 

 Creek flows from the west into the Yellowstone, between the upper and 

 lower falls. Just before it enters tlie Yellowstone, it flows over a series 

 of ridges and breccia, making one of the most beautiful cascades in this 

 region ; hence the name of the little stream. Like all these rapids or 

 falls, it is formed of the more compact basalt, resisting the wear of the 

 atmospheric forces, while the breccia readily yields. As this little cas- 

 cade is seen from the east branch of the Yellowstone, dividing up into a 

 number of little streams and rushing down from ledge to ledge until it 

 reaches the bed of the river, it presents a picture of real beauty. High 

 up on Cascade Creek, almost a mile above its mouth, the channel is carved 

 out of a kind of sedimentary volcanic sandstone, arranged in regular 

 strata; most of it is so largely made up of worn fragments of obsidian 

 and other igneous rocks that it might be called a pudding-stone. The 

 natural sections in the channel of this creek aid us much in forming an 

 idea of the extent of the modern lake deposit, which doubtless began 

 in Tertiary times, and continued on up into or near the present period. 

 The surface everywhere is covered with fragments of volcanic rocks, 

 apparently quite modern, so that it presents that peculiar appearance, 

 which 1 have often alluded to, like the refuse about an old foundry. 



But the objects of the deepest interest in this region are the falls 

 and the Grand Caiion. I will attempt to convey some idea by a de- 



