QUATERNARY AGE. — GLACIAL PERIOD. 531 



vary from fine lines to furrows three or four inches deep; but they are occasionally a 

 foot deep and several feet wide ; or even two feet deep, as on the top of Monadnock 

 (Hitchcock); and even eight to ten feet deep, making great mouldings of the surface, 

 as in the Connecticut River sandstone, in North Haven (near New Haven, Ct.); and 

 four to six feet in compact limestone, near Ithaca, N. Y. At the same time, the varia- 

 tions, from broad smooth planings and ploughings to deep groovings and line scratches, 

 show variations in the moving mass. The channels are sometimes made of broken 

 lines, or successions of slight curves, as if from hitches in the progress of the gouging 

 agent; and the edge of a layer, where there was a sudden descent, is occasionally 

 chipped off, as if the heavy body had gone down with a jump. 



Rocky ledges have been left with polished and rounded surfaces, 

 like those called, from their shape, in the glacier regions of the Alps, 

 roches moutonnees (or sheep-backs) (p. 699). 



Again, the scratches exist over the higher summits of the country, 

 as well as over the lower, — occurring on Mount Mansfield, in the 

 Green Mountains of Vermont, 4,400 feet above the sea level, and on 

 the White Mountains to a height of 5,500 feet. Moreover, the north 

 side of a ridge or summit has often been smoothed off and made 

 steep, when the southern has been left with a gradual slope. The 

 north side, in such cases, is called in Sweden the stoss or struck side. 



2. Direction of the Scratches. — The direction of the scratches corre- 

 sponds with that of the movement of the Drift, being in general south- 

 ward, or southeastward in New England, but southwestward in West- 

 ern New York, near Lake Huron, Lake Superior, and Lake Winnipeg. 



On the higher summits of northern New England, the average course is approxi- 

 mately S. 40° E. ; to the eastwai-d, in Maine and adjoining parts of Canada, S. 50° to 

 S. 66° E., increasing in easting to the eastward; in western Connecticut and New York 

 adjoining, about S. 25° E. ; in western New York and on the eastern side of Lake 

 Huron. S. 35° W. ; on the northeast side of Lake Huron, S. 37°-45° W. 



Over the lower lands of a country, there is commonly some conformity to the general 

 slopes of the surface, or to those of the principal river valleys, as stated with regard 

 to the Drift itself. "While the scratches follow the course of the Connecticut valley, in 

 the valley itself (averaging S. to S. 15° E., for 100 miles north of Massachusetts; S., 

 in Massachusetts: S. 10°-25° YV\, in Connecticut), to the east, as well as west, of the 

 valley, over the higher land, the same southeasterly course prevails that is usual over 

 the more elevated parts of New England. (Am. Jour. Sci., III. ii. 233.) Along the 

 valleys of the Lamoille, the Winooski, and Otter Creek, in Vermont, of the Merrimack 

 in Massachusetts, and in the lower part of the Lake Champlain valley, the scratches have 

 the directions nearly of the valleys. In western New York and western Canada, and 

 about the eastern borders of Lake Huron, the prevailing course of the scratches is 

 southwest : but. at many points south of the eastern arm of Lake Huron, called 

 Georgian Bay, as recorded by Logan, it is southeast; and this is so, apparently, be- 

 cause this is the course of the Georgian Bay depression. 



There are sometimes two or more sets of groovings, differing in 

 direction. For example, in western New York, there is, in addition 

 to the southwest system, a subordinate south system (Hall) ; and, on 

 Isle La Motte. in Lake Champlain, there are eight sets (Adams), 

 although usually not over two or three in Vermont. 



