Identifier: annualreportofun1711geol (find matches)
Title: Annual report of the United States Geological Survey to the Secretary of the Interior
Year: 1880 (1880s)
Authors: Geological Survey (U.S.)
Subjects: Geological Survey (U.S.) Geology Water-supply Forest reserves Mines and mineral resources
Publisher: Washington : G.P.O.
Contributing Library: University of Illinois Urbana-Champaign
Digitizing Sponsor: University of Illinois Urbana-Champaign

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further-more, they probably extend beneath the city, w here they are coveredby later deposits. At various places along the western side of the Willamette Valley,between forest drove and Corvallis. a number of bowlders of graniteand schist were observed under conditions that strongly suggest transportation by ice, probably in the form of icebergs, floating upon theWillamette Sound. The first one noted was upon the hill slope near the county stonequarry, a mile south of Dilley. at an elevation of L20 feel above thesea. The bowlder is of biotite granite, and is about 2.\ feet in diam-eter. Chloritic bowlders were seen near Amity, at an elevation of 190feet. A few miles north of Corvallis granite bowlders occur, and 11 ..O ; -Q c :-2 3 3 Fio. 16—Section of cliff at Allium, near Portland. 1,Sand; 2, Coarse gravel; J, Sand, pebbles, and smallbowlders. 1 In (lie Trans. St. Louis Acad. Sri., Vol. I, 1800, )>. 121, Shuinard deserilies a Miocene I.eda from alew miles south of Oregon City.
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PLEISTOCENE. 487 miles southwest of that city bowlders, not only of granite but also ofglaucophane schist, were seen by the roadside at an elevation of overIoO feet above sea level. No striae or other marks showing glacialorigin or ice transportation were seen on the bowlders, but that theyare erratics carried there from the mountains is evident, for no suchrocks are known in the places where they occur. Mr. W. A. Pomeroy,of Oswego, Oreg., informs me that in the vicinity of the Prosser mine,8 miles south of Portland, there are angular bowlders of syenite, rang-ing in weight from a few pounds to several hundred, widely scatteredin valleys and on the tops of hills and knolls 800 to 1,500 feet high. During the Glacial period, as pointed out by Professors Newberry,Russell, and others, glaciers of the Cascade Range were large, andextended almost if not quite into Willamette Valley; for those ofMount Shasta in California at that time reached the very base of themountain upon the western sid

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