, 
X 
‘ 
5 
3 
Mesozoic and Cenozoic Geology and Paleontology. 211 
by any currents of water sweeping over the surface, under some great 
general cause, but that it has all been quietly and silently effected by 
the simple agency of rain and frost, acting uninterruptedly through a 
vast period of time. 
3d. That a large portion of the Be saiial detritus of the West, even 
in those regions where drift bowlders are met with, must have had its 
origin in the suberial destruction of the rocks, the soluble portion ot 
them having been gradually removed by the percolating water, while 
that which remains represents the insoluble residuum, the sand and 
clay, which was originally present in smaller quantities in the strata 
thus acted on. 
Bowlders of Laurentian rocks* are found in considerable numbers 
scattered over the high table-land of western Canada, south of Georgian 
bay. <A portion of this region attains an elevation of 1,760 feet above 
the sea. These blocks are generally more angular than those from a 
similar source found at lower levels, and are associated with many 
others of local origin. 
The stratified drift is separable into two divisions in western 
Canada, the lower of which, called the Erie clay, had been partially 
worn away before the deposition of the upper so as to produce un- 
conformability. The Erie clay is commonly more or less calcareous, 
and always holds bowlders in greater or less abundance. The thick- 
ness at any one place does not exceed 200 feet, but clays belonging to 
this division occur at various levels from 60 feet below the surface of 
Lake Ontario to 100 feet above Lake Huron, showing differences in 
level of about 500 feet. It occurs along the north shore of Lake Erie 
from Long Point westward to the Detroit river, and appears to under- 
lie the whole country between this part of the lake and the main body 
of Lake Huron. It is found at Owen sound, and along Nottawasaga 
river, and along the shores of Lake Ontario as far east as Brockville. 
The upper division is called the Saugeen clay, because it is well ex- 
posed along the Saugeen river. It consists of a thinly-bedded, brown 
calcareous clay, generally containing but few bowlders or pebbles. 
This division occurs also at all levels from Lake Ontario to 100 feet 
above Lake Huron, showing differences of level almost equal to that 
of the lower clay. 
At the oil wells, on the 13th and 14th lots of the 10th range of Ennis- 
killen, two beds of gravel, of four and five feet respectively, have been 
met with in the clay, at depths of ten and forty-four feet from the sur- 
* Geo. Sur. of Canada, 1863. 
