104 



SCIENCE. 



[N. S. Vol. IX. No. 212, 



The region under discussion covers an 

 area from the Northern Pacific Railroad to 

 the Canadian boundary, sixty miles east 

 and west by one hundred and twenty north 

 and south. The following topics were taken 

 up : Terranes — A. Eruptive, general ab- 

 sence of basalt, the schists, granites and 

 gneisses, greenstones, andesite of Glacier 

 Peak, volcanic tuff and dust, acid and basic 

 .dikes, the source of the Columbia lava. B. 

 Sedimentary, Pretertiary, i. e., Carboniferous 

 and Triassic strata, including the Similka- 

 meen system and the Ventura system. C. 

 Tertiary strata, including Snoqualame slate, 

 Winthrop sandstone, Camus sandstone, 

 Swank sandstone, Roslyn sandstone, Ellens- 

 burg sandstone. Abundance of fossil leaves. 

 D. Pleistocene strata, moraines and valley 

 gravels. 



Structural Geology. — Domes, includ- 

 ing the Cascade dome, the Wenatchee 

 dome. Folds and faults. Physiography: The 

 Cascade peneplain, the Cascade plateau, 

 dissection of the Cascade plateau. Mature 

 topography. Low-grade valleys. 



Ancient Glaciers. — On the east side of 

 the Cascades : Yakima glacier, Wenatchee 

 mountain glacier, Icicle glacier, Wenatchee, 

 Chelan, Methow, Okanogan glaciers. On the 

 west side of the Cascades : Sauk glacier, 

 Skagit glacier, confluent ice sheet. Absence 

 of northern drift. Gravel deposits. 



Terraces. — Great terraces of the Colum- 

 bia, the Snake and Spokane, due to climatic 

 changes. No evidence of recent submerg- 

 ence ; absence of white silt. 



Existing Glaciers of the Wenatchee 

 mountains and the Cascades. 



Climate. — The rainy western slope with 

 dense forests and the drj'er eastern slope 

 with open forests and grass. 



Economic Geology. — Coal, gold, copper, 

 iron, building stone, clays, etc. 



In discussion Bailey Willis expressed 

 doubts as to the divisibility of the Tertiary 

 sandstones into so many distinct members, 



believing that combination would be neces- 

 sarj^ He also argued that the domes were 

 due to cross-folding rather than to lacco- 

 lithic uplift, as ui-ged by Russell. S. F. 

 Emmons suggested lava dams as the cause 

 of the terraces rather than submergence or 

 change of climate. G. M. Dawson said 

 that the white silt was not to be expected 

 in the region under discussion and favored 

 submergence and glacial ice as the causes 

 of the terraces. In reply I. C. Russell 

 stated that the lava flows were older than 

 the terraces, as the terrace gravels were 

 present in cafions cut in the lava. He ad- 

 mitted that Willis's views regarding the 

 sandstones and the uplifts might prove cor- 

 rect and that the causes of the terraces was 

 obscure. 



The Society then adjourned for lunch. On 

 reassembling the subject-matter of W J 

 McGee's paper was introduced by W. H. 

 Holmes. Holmes described the discovery 

 of bones and artefacts on the surface in the 

 vicinity of the California gravels that had 

 yielded buried skulls and implements, and 

 detailed the stories of old residents regard- 

 ing the large part that practical jokes 

 played in the discovery of the remains. He 

 illustrated the geology of the Table Moun- 

 tain region by sections, and developed the 

 general argument that the relics were those 

 of Digger Indians, who are still in resi- 

 dence, or were within the period of the gold 

 miners. He was followed by W J McGee 

 before discussion opened. 



Geology and Archceology of the California Gold 

 Belt. W J McGee, Washington, D. C. 

 In continuing the paper of Holmes the 

 speaker sketched the geological history of 

 the Western Sierras, emphasizing the Ter- 

 tiary age of the gravels, the ancient drain- 

 age ; the inflow of tuffs and lavas ; tlie sub- 

 sequent erosion of the present steep river 

 caflons to a depth of 2,000 feet. He stated 

 that in this time the fauna and flora had 



