754 



SCIENCE 



[N. S. Vol. XXIX. No. 749 



and the soft cross-bedded sand contains the im- 

 pression of the skin that entirely envelops the 

 bones, which are nearly all in normal position. 

 The contents of the stomach are also preserved. 

 It will be mounted as in death by the American 

 Museum of Natural History. 

 Isobases of Post-Algonquin Elevation Across Lakes 



Michigan and Huron: J. W. Goldthwait. 



The results of precise measurements of altitude 

 of the Algonquin beach, during the last four 

 years, are here summarized. 



With data collected last summer for the Ca- 

 nadian Geological Survey, isobases of the de- 

 formed water-plane are constructed over the 

 region east of Lake Huron and Georgian Bay in 

 Ontario. It is found that at the south end of 

 Lake Huron the Algonquin beach is horizontal, 

 and twenty- five feet above the present lake; that 

 forty or fifty miles north of Sarnia the beach be- 

 gins to rise towards the north-northeast, at a 

 rate which increases slowly to three feet per mile 

 over Lake Simcoe, and then very rapidly north of 

 Orillia to five feet per mile near the pre-Cambrian 

 border. Beyond that, to North Bay, the warping 

 seems to have been much more irregular. 



The attitude of the deformed Algonquin plane, 

 south of the pre-Cambrian bounaary in Ontario, 

 is compared with that over the north half of 

 Lake Michigan, three hundred miles away. Iso- 

 bases drawn across Lakes Michigan and Huron 

 emphasize the close correspondence in the details 

 of post-Algonquin uplifts in these two regions. 



Conclusions are drawn as to: (1) The regular- 

 ity of the uplifts over the Great Lake region, 

 south of the pre-Cambrian border; (2) the south- 

 ern limit of the uplifts; (3) the original altitude 

 of Lake Algonquin above sea level and (4) the 

 cause of the uplifts. 

 Sand and Oravel Resources of Nebraska: G. E. 



CONDEA. 



This paper is now in press. It consists of 210 

 pages of text and 82 figures in Part 3 of Vol. 3, 

 Nebraska Geological Survey. 

 The Glacial Character of the Yosemite Valley: 



F. E. Matthes. 



Tlie Yosemite is a stream-worn canyon modified 

 by ice erosion. That it is primarily a product of 

 stream cutting no one familiar with its relations 

 to the rest of the Merced Eiver canyon, and with 

 the position which the latter occupies in the series 

 of great transverse valleys of the Sierra Nevada, 

 will question. That it has been invaded by 

 glaciers, on the other hand, and has to some 

 extent been remodeled by them, is amply attested 



by the threefold record of glaciation, viz., the 

 moraines, striiE and glacial sculpture in and about 

 the valley*. The glacial character of the Yosem- 

 ite is however by no means equally pronounced 

 throughout: most accentuated at the upper end, 

 it rapidly fades downvalleyward and ultimately 

 vanishes at the lower end. This gradation is ex- 

 plained by the circumstance that the valley lay 

 close to the periphery of the glaciated zone of 

 the Sierra. In earlier glacial times the ice ad- 

 vanced considerably beyond the foot of the val- 

 ley, but the later glaciations appear to have been 

 more moderate, the ice front seldom reaching 

 down to the " gateway." The lower portion of 

 the valley bears therefore no fresh signs of glacia- 

 tion, and since the older icework has been con- 

 siderably obliterated by subaerial erosion, its 

 glacial character can now scarcely be detected ex- 

 cept by the trained eye. The upper half of the 

 valley, Tenaya Canyon and the Little Yosemite, on 

 the other hand, having sufiFered more frequent, 

 more intense and also more recent glaciation, 

 have been extensively remodeled and present to- 

 day a glacial aspect of the most pronounced and 

 clear cut type. 



The disparity between the lower and upper 

 portions of the Yosemite is further heightened by 

 the presence in the latter of a variety of aberrant 

 sculptural features. The ice had to deal here with 

 rock-masses of singularly variegated structure, 

 ranging all the way from the schistose to the 

 massive. Since ice accomplishes most of its work 

 by plucking, its effectiveness as a sculpturing agent 

 is largely determined by the fissility of the mate- 

 rials it attacks. Its action in the Yosemite was 

 therefore necessarily a selective one, guided and 

 controlled locally by the direction, attitude and 

 distribution of the joints. Thus it was permitted 

 to achieve large results where the intensity of 

 the fissuring favored plucking, as in the region 

 about the Cathedral Spires, while it found itself 

 almost powerless against such huge masses of 

 unjointed rock as Mt. Broderick, El Capitan or 

 the Cathedral Rocks. Again, the remarkable 

 wall-like smoothness as well as the orientation of 

 the cliflfs over which the waterfalls plunge, re- 

 flects the strong directive influence of the rock 

 structure. 



LIST OF PAPEES BEAD BBFOEE THE QEOLOQICAL 

 SOCIETT OF AMEEICA 



Abstracts of these papers have been sent to 

 Science by the secretary of the Geological So- 

 ciety of America. 



