The Drift or Boulder Formation. 331 



rising into hills 200 to 400 and sometimes 500 feet above its 

 surface, with the exception of the mouths of several transverse 

 valleys occuring on the left bank, among the slates, sandstones 

 and limestones on the north side of the anticlinal axis. The 

 general valley of the lake, thus bounded, presents several gentle 

 turns, the directions connected with two of which, reaching down 

 to the mouth of the Keepawa River (thirty-five miles) are 158^, 

 191°, 156^, numbering the degrees from north as zero round by 

 east. The parallel grooves in these reaches of the valley turn 

 precisely with their bearings, and they are registered on various 

 rounded and polished surfaces projecting into the lake, and some- 

 times rising to thirty and forty feet over its level. It was not 

 easy to follow them to higher surfaces, for these usually were 

 covered with the moss and trees of the forest, but they were 

 occasionally traced to spots where they thus became concealed. 

 These projecting points never were found to deflect the grooved 

 lines in the slighest degree, and one remarkable instance of this 

 occurs on the east side of the lake about a mile above the lower 

 large island, at the south horn of a pretty deep bay. The rock 

 belongs to the slate conglomerates, and it is composed of pebbles 

 and boulders of igneous origin. Its face is a clean, smooth, rounded 

 surface cutting through the pebbles, which are polished down 

 with other parts. It is very deeply grooved with parallel furrows 

 in the bearing 160"^, and from the water's edge they run obliquely 

 up the face (an inclined plane of 60° in an upward direction of 

 102*^,) and continue on in the same bearing of 160° on the 

 rounded or rather flattened top, thirty -five feet above the lake ; so 

 that whatever body moving downward in the valley may have 

 caused the grooves ; it was not deflected by meeting with a 

 surface, presenting a thirty-five feet height of front, so steep as 60°, 

 notwithstanding it impinged upon it at an angle of no more than 

 32°. On the summit of the rock there is another set of parallel 

 grooves, not so deeply marked, which cross the former at an 

 acute angle, the bearing being 185°. In another place, about 

 six miles higher on the lake, on the same side, a polished surface, 

 not over four or five feet above the water, belongs to the very 

 base of the limestone formation. Vast boulders and fragments of 

 the sandstone below lie in a calcareo-arenaceous cement, some of 

 the imbedded circidar slices or half boulders being nine feet in 

 diameter, while in some parts the solid sandstone strata are seen, 

 and great cracks or worn fissures in them are filled with cement. 



