72 



SCIENCE. 



[N. S. Vol. VII. No. 159, 



masses in a canyon which in grandeur is only- 

 second to the Canyon of the Colorado. It is an 

 abrupt trench cut to a depth of over 5,000 feet 

 in the basaltic plateau. The deepest and most 

 impressive part lies in the vicinity of the Seven 

 Devils, a group of peaks rising to elevations 

 exceeding 9,000 feet on the eastern side of the 

 river. From the summits of these there is a 

 sharp and continuous slope of 8,000 feet down 

 to the level of the river. The exposures along 

 the canyons are magnificent, showing from 

 1,000 to 4,000 feet of horizontal lavas' covering 

 a series of older slates and greenstones. 



The Salmon River Canyon, for a long dis- 

 tance above its junction with the Snake, is be- 

 tween 4,000 and 5,000 feet deep. Except in its 

 lowest portion, it is out in the rocks of the older 

 series. Granitic rocks, forming a large part of 

 the great Idaho granite area, occupy a large 

 space in Idaho adjacent to the Columbia lava. 

 Instead of being of Archean age, as has been 

 hitherto supposed, the granite is probably post- 

 Carboniferous, as shown by the contact meta- 

 morphism of the Paleozonic series adjoining on 

 the north. 



This series of slates, limestone, schist and 

 greenstones present the greatest similarity to 

 the Auriferous slates of the Sierra Nevada. 

 Round Crinoid stems were found in one of the 

 limestone lenses. Excellent exposures are 

 found in the lower Salmon River Canyon and 

 along the Snake River. The Columbia lava 

 flows are of Miocene age. They consist nearly 

 exclusively of massive basalt, and are piled up 

 one on another in seemingly endless succession. 

 Slight differences of structure make the indi- 

 vidual flows conspicuous and from a distance 

 the exposures along the canyon side appear like 

 those of a sedimentary series. The lava flows 

 were poured out over an exceedingly uneven 

 surface of deep valleys and precipitous moun- 

 tain ranges. The latter tower far above the 

 summit of the lava plateau, while the bottom 

 of the former lie below the level of the river. 

 Coupling this evidence with the fact that the 

 sediments in the lower Snake River Valley, 

 above Weiser, are of great depth, their bottom 

 probably not being far from sea level, it appears 

 that this whole area has sufl^ered a depression 

 since pre-volcanic times. The great outpouring 



of the Columbia lava evidently dammed a gap 

 between the two high pre-volcanic ranges, the 

 Blue Mountains of Oregon on the west and the 

 Salmon River Ranges on the east. This barrier 

 produced a great lake, the Miocene and Pliocene 

 sediments of which now fill the upper Snake 

 River Valley. The inland sea overflowed its 

 barrier, established an outlet and the mighty 

 volume of water has worn a canyon which 

 eventually drained the lake. 



At this meeting the Society elected officers for 

 the ensuing year. These are : President, Arnold 

 Hague : Vice-Presidents, Joseph S. Diller and 

 Whitman Cross ; Treasurer, M. R. Campbell y 

 Secretaries, C. Willard Hayes and T. W. 

 Stanton ; Members-at-Large of Council, S. F. 

 Emmons, George P. Merrill, "W. H. Weed, 

 David White and Bailey Willis. 



W. F. MOESELL. 



U. S. Geological Survey. 



NEW BOOKS. 

 The Smithsonian Institution, 1846-1896. The 

 History of its first half century. Edited by 

 George Brown Goode. City of Washing- 

 ton. 1896. Pp. 856. 



Audubon and his Journals. Maria Axtdubon. 

 With zoological and other notes by Elliott 

 CouES. New York, Charles Scribner's Sons. 



1897. Vol. I., pp. X + 532. Vol. II., viii + 

 535. $7.50. 



Revision of the Orthopteran Oroup Melanopli 

 (acridiidse). With special reference to North 

 American Forms. Samuel Hubbard Scud- 

 DER. Washington, Government Printing 

 Office. 1897. Pp. 421. 26 plates. 



An Elementary Course of Infi.nitesim.al Calculus. 

 Horace Lamb. Cambridge, The Univer- 

 sity Press ; New York, The Macmillan Com- 

 pany. 1897. Pp. XX + 616. $3.00. 



Theoretical Mechanics. A. E. H. Love. Cam- 

 bridge, The University Press; New York, 

 The Macmillan Company. 1897. Pp. xiv + 

 370. $3.00. 



Lessons With Plants. L. H. Bailey. New 

 York and London ; The Macmillan Company. 



1898. Pp. xxxi + 491. $1.10. 



