THE PARALLEL ROADS OE GLEN ROY. 
33 
barriers, presented by McCulloch and Sir T. 
Lander-Dick, that of continental upheavals and 
subsidences, advocated by Sir Charles Lyell 
and Charles Darwin, that of inundations by 
great floods, maintained by Professor H. D. 
Rogers and Sir George Mackenzie, that of 
glacial action, brought forward by myself, 
have been duly discussed with reference to 
this difficult case; all have found their advo¬ 
cates, all have met with warm opposition, and 
the matter still remains a mooted point; but 
the one of all these theories which shall stand 
the test of time and repeated examination and 
be eventually accepted will explain many a 
problem besides the one it was meant to solve, 
and lead to further progress in other direc¬ 
tions. 
I propose here to reconsider the facts of the 
case, and to present anew my own explanation 
of them, now more than twenty years old, but 
which I have never had an opportunity of 
publishing in detail under a popular form, 
though it appeared in the scientific journals of 
the day. 
Before considering, however, the phenomena 
of Glen Roy, or the special glacial areas scat- 
2* C 
