ABSTRACTS OF PAPERS 111 



"Helderberg limestone" and "Helderberg group" ; the rocks contain a great 

 number of characteristic fossils, especially of marine forms. On the slope 

 appear Hudson shales, and flaggy sandstones of the Hamilton formation crown 

 Countryman Hill. The deep amphitheater at Indian Ladder lias been worn 

 out by the water of a small stream. 



There is now a small museum and library in the park, and the Geological 

 Survey has set up a bench-mark. It is hoped that very soon the cottage 

 building for the reception of guests will be completed, so as to afford com- 

 fortable shelter for visiting geologists who wish to study this Mecca of geolo- 

 gists. The library would be glad to receive geological publications linving any 

 {tearing on the local conditions ; such mail should be addressed to the Curator 

 of John Boyd Thacher Park, East Berne, New York. 



Presented by title in the absence of the author. 



The next paper was oii address made by Mr. Diller as retiring Vice- 

 President of Section E of the American Association for the Advancement 

 of Science, under the title 



RELIEF OF OUR PACIFIC COAST 

 BY J. S. DILLER 



(Ahstract) 



The continental feature bordering the Pacific coast of the United States is 

 a mountain lielt of surpassing grandeur and composed in general of two lines 

 or ranges of mountain elevations with a depression between. For the most 

 part the two lines of mountains appear to be parallel with each other and the 

 coast, the Sierra Nevada and the Cascade ranges on the east and the Coast 

 ranges, including the Klamath Mountains of California and Oregon and the 

 Olympic Mountains of Washington, on the west, from the Mexican line to that 

 of British Columbia. Cross-folds connect the side ranges and separate the 

 great valley of California from the Willamette Valley of Oregon. 



The Sierra Nevada is composed of folded sediments and igneous rocks of 

 various ages, from Silurian to .Jurassic, and faulted and tilted as one great 

 block, with long gentle slope to the west and steep slope to the east. 



The Cascade Range is essentially volcanic and due mainly to volcanic up- 

 Iiuilding, though partly to uplifting, from Mount Adams, in Washington, to 

 liassen Peak, in Califoi'nia ; but beyond these limits the older crystalline rocks 

 ri.se to the surface. 



The Klamath Mountains are in large measure like the Sierra Nevada in 

 their rocks, although more fossillferous, but differ in structure, being char- 

 acterized by broadly curved thrust-faults with the overthrust into (he i-oncave 

 curve and thus toward the Pacific Ocean. 



The Coast Ranges of California and Oregon are composed almost wholly of 

 Me.sozoic and Tertiary rocks. In California the Coast Range rocks arc greatly 

 crushed and fauKod. hut in Oregon the coinprcssion has liooii nim-li less 

 intense. 



The scclinii MiljdiiiiKMl ill 1 o'clock j). m. 



