38 W. UPHAM — giants' kettles eroded by MOULIN TORRENTS 



in its upper part and 14 feet below. On a later page of the same report, 

 in a discussion of the drift and striation of the northeastern part of this 

 state, Emmons wrote of " the numerous potholes in ledges of rock now 

 distant from any stream and far above all the creeks in the region/' ^ 



In southeastern New York potholes which may be of glacial origin 

 have been described by Doctor N. L. Britton in the Bronx valley, 2 to 3 

 miles north of Williams Bridge, two having de])ths respectively of about 

 9 and 10 feet,t and others were noticed by Professor Oliver P. Hubbard 

 in the Hudson valle}^, opposite to the town of Catskill.l 



PENNSYLVANIA 



The most remarkable known of these giants' kettles, whether we con- 

 sider their size or the manner of their occurrence and discover}'', are two 

 found in 1884 and 1885 in Lackawanna county, Pennsylvania, about 

 three miles northwest of Archbald. As described b}^ Mr C. A-. Ashburner, 

 the Archbald potholes are 1,000 feet apart and were both discovered in 

 coal mining, their bottoms being in the coal bed. When the drift filling 

 the one first discovered was cleared out, it was found to be 38 feet deep, 

 with a diameter of about 15 feet at the bottom, increasing to a maximum 

 of 42 feet and a minimum of 24 feet across its top. The second pothole, 

 of similar basal diameter in the coal bed, had not been cleared of its 

 drift contents, but it is known, from the leveling and test-pits or borings 

 of the mining company, to have a depth of about 50 feet in the rock, 

 with a covering of 15 feet of drift above.§ 



IDAHO 



A very interesting series of glacial gravel deposits in north central 

 Idaho, resting along a part of its course on a rock bed that is much 

 waterworn and marked by potholes, is described by Professor George H. 

 Stone. It is a short distance south of Elk Cit}^ on head streams of the 

 south fork of the Clearvyater river. The area was covered during a part 

 of the Glacial period by a piedmont ice-sheet or broad glacier, deploy- 

 ing westward from the Bitter Root mountain range, nearly as the present 

 Malaspina ice-sheet of Alaska is spread out between Mount Saint Elias 

 and the sea. These gravel deposits belong in the same class with the 

 prolonged series of esker or osar ridges and gravel plains which are so 

 grandly developed in Maine and in Sweden, and of which occasional 

 examples occur also, although of less extent, in nearly all broadly gla- 



* Geology of New York, part ii, survey of the second geological district, 1842, pp. 410, 411, 424. 



t Trans. N. Y. Acad. Sci., vol. 1, 1882, pp. 181-183 ; Amer. Jour. Sci., third series, vol. 25, p. 158, Feb- 

 ruary, 1883. 



X Trans. N. Y. Acad. Sci., vol. 9, 1890, p. 3. 



g Geol. Survey of Pa., Annual Report for 1885, pp. 615-625, with a map, sections, and two plates 

 (views from pho\,ographs of the first pothole when cleared out for use as an air shaft). 



