GEOLOGY OF THE NORTH CREEK QUADRANGLE 63 



of feet above the comparatively lowland of the region. A com- 

 parison of the North Creek sheet with all other published Adiron- 

 dack maps shows that, from the physiographic standpoint, this 

 region is noticeably different from the Adirondacks in general. 



Some of the best examples of such domes are: Kelm, Chase, 

 Tripp, Hackensack, Moon, Heath, Potter, Birch, No. 9, Little, 

 Crane, Huckleberry, Mill, Stockton, and Prospect mountains. The 

 greatest of these domes is Crane mountain which rises 2000 feet 

 above the immediately surrounding country. The upper 1000 to 

 1500 feet of this mountain are very steep to almost precipitous 

 on all sides except the north making this great rock dome a grand 

 sight as viewed from Thurman (see plate 8). ]Mill and Stock- 

 ton mountains deserve special mention because they rise as two 

 great isolated masses above the comparatively low and featureless 

 surrounding country and form conspicuous features of the land- 

 scape as viewed from any of the higher points for a number of 

 miles around (see plate 13). As viewed from the south, Potter 

 mountain is a fine example of a rock dome which rises 700 feet 

 above the general level of the country (see plate 14). 



The domes may be classified under three headings according to 

 shape: (i) those with nearly circular bases and which are very 

 symmetrical and almost uniformly steep on all sides, as Potash, 

 Mill, and Stockton mountains and the top of Kelm mountain; (2) 

 those with elliptical bases and represented by nearly concentric 

 elliptical contours to the summit, as Moon, Birch, No. 9, and 

 Huckleberry mountains; and (3) those of irregular shape as shown 

 on a large scale by Crane mountain and many smaller masses. 



After climbin«T all the domes the writer has been impressed by 

 the almost universal occurrence of exfoliation on a large scale over 

 their surfaces. These mountains are literally peeling or shelling 

 off by the removal of exfoliation sheets of great size, some having 

 been noted as much as 50 to 75 feet across and from i to 3 feet 

 thick. Among many other good places to observe this phenomenon 

 are on the west or south sides of Moon, Crane, or Huckleberry 

 mountains. Not infrequently, especially during the fall and spring 

 months, slabs loosen up and go thundering down the mountain sides. 

 Though the rocks are all clearly gneissoid, the exfoliation appears 

 entirely to disregard this structure and often great sheets come otf 

 at right angles to the foliation. 



This very common occurrence of exfoliation domes in the region 

 the writer believes to be due to a combination of factors especially 



