SCIENCE. 



[N. S. Vol. V. No. 105. 



tion under his instruction and supervision. 

 Dr. John Locke was his geological assistant 

 in this work. The determination of fossils 

 of geological horizons was yet very imper- 

 fect, and the main conclusion arrived at 

 was that the lead-bearing limestones were 

 probably older than the Carboniferous. 



1841. In 1841 the Wilkes Exploring 

 Expedition, which, since 1838, had been 

 cruising along the coasts and among the 

 islands of the Pacific ocean, reached the 

 coast of Oregon. Near the mouth of the 

 Columbia river the ship Peacock on which 

 was Prof. James D. Dana, the geologist of 

 the Expedition, was wrecked, entailing the 

 loss of all the latter's personal effects as 

 well as many of his collections. 



His loss was in the end, however, a gain 

 to geological science, for on his trip across 

 the Cascade mountains, and to San Fran- 

 cisco through the mountains of Oregon, 

 past Mt. Shasta and down the valley of the 

 Sacramento, he gained a personal knowl- 

 edge of the geological conditions of the 

 West, which was invaluable to him in later 

 years when he was called upon to discuss 

 the observations of later observers in the 

 preparation of his Manual of Geology. 



In his report upon the geology of the 

 Wilkes Expedition, Dana calls attention to 

 the fact that the slates of the Umpqua and 

 Shasta regions resemble gold-bearing rocks 

 of other regions, but it does not appear that 

 he found actual evidence of the occurrence 

 of gold. 



He did observe the occurrence of sand- 

 stone dikes intersecting sandstones and 

 shales near Astoria, and drew some inter- 

 esting conclusions as to changes of level of 

 the Coast region, which were further evi- 

 denced by the fiords along the coast and 

 terraces along the river valleys ; the latter 

 he reasoned could not be explained by the 

 current hypothesis that they were deposited 

 in barrier lakes. As regards the whole 

 Kocky_Mountain region he concludes that 



it was probably in a great measure sub- 

 merged until Cretaceous or later time. 



1842-5. The three famous expeditions 

 of Fremont were conducted in the years 

 1842, 1843-4 and 1845 respectively. They 

 covered a very large part of the Cordil- 

 leran region, but unfortunately no geologist 

 was attached to the expedition. Fremont 

 himself, however, was a scientifically edu- 

 cated man, and had served under Nicollet 

 in his expedition up the Missouri. His 

 scientific notes, and the fossils and rocks 

 collected, were afterwards worked up by 

 Prof. James Hall. 



Among the specimens thus brought and 

 described were detected Niobrara lime- 

 stones, upturned against the granites near 

 Pike's Peak ; green clays from the Eocene 

 of the Bridger Basin, thought to resemble 

 Cretaceous green sand ; coal from the Muddy 

 on the western edge of that basin, with 

 fossil ferns which Hall said were not Car- 

 boniferous ; fresh water shells from the Ter- 

 tiary formations there and at the head of 

 the Uinta River, on the east slope of the 

 Wasatch Mountains ; various eruptive rocks 

 from the Snake Eiver Valley, Blue Moun- 

 tains and the Cascade Eange ; and a series 

 of specimens from a bluff 700 feet high, 

 which consisted largely of volcanic ash 

 with fresh water fossil infusoria, which 

 were probably formed of the Tertiary beds 

 of the John Day Eiver. 



1846. In the spring of 1846 Dr. Wis- 

 lizenus, ' a German by birth, but an Ameri- 

 can by choice,' as he characterizes himself, 

 and evidently a man of wide scientific cul- 

 ture, undertook an examination into the 

 geography and natural history of northern 

 Mexico and Upper California at his private 

 expense. While on his way west the war 

 between the United States and Mexico 

 broke out, and he was detained a prisoner 

 for six months in the state of Chihuahua. 

 Finding it impracticable to continue his 

 work unaided, upon the arrival of the 



