FOX-STRANGWAYS : GLACIAL PHENOMENA NEAR YORK. 
19 
raises the question as to which is the older of the two, and, contrary 
to natural supposition, inclines to the view that the northern or 
York ridge was formed first. As to their relative age, the distance 
between them is so slight, considering the great extent of this glacier, 
which must have been over 100 miles in length with an average width 
of 20 miles, that one would be inclined to regard these two mounds 
as practically part of one and the same moraine. If the valley 
was stripped of the more recent superficial beds which now cover it, 
there is little doubt that several other parallel ridges would be dis- 
covered both to the north and south of those that are now exposed ; 
and it is very probable that the isolated mounds of drift seen here 
and there in the vale are portions of such mounds just appearing 
through the thick covering of later beds. If such is the case, it 
would be natural to suppose that the most southerly ridge is the 
older, and the more northerly the younger, or as Mr. Kendall says 
"a moraine of retrocession." 
Of the internal structure of these ridges we know very little. 
The sections about York frequently show highly contorted beds of 
clay and sand, proving that great pressure has been exerted against 
them since their first deposition, and it is very probable that many 
of the out-crops marked on the map are due to similar contortions. 
The fact of clay being now seen at the surface is no proof that the 
glacier over-rode the moraines, "plastering their inner and outer 
faces with clayey ground moraine." 
Mr. Kendall seems to see no difficulty in a glacier of this size 
overriding its moraine. Such a glacier 1 admit may have passed 
over the spreading beds of drift to the west of York, but I cannot 
conceive it passing over the narrow ridge to the east without dis- 
persing the materials and entirely obliterating its character as a 
ridge. It has been objected that a great part of these mounds is too 
clayey to be moraine ; but we must bear in mind that this glacier 
at one time probably extended much further to the south, and also 
that the valley to the north undoubtedly contains a good deal of 
true boulder clay ; a portion of which would be borne forward by the 
glacier, and mixed with the more gravelly morainic material at its 
terminus. Until a better section has been exposed of the internal 
