124 THE ROYAL SOCIETY OF CANADA 
and to the effects of evaporation, and changing it may be under these 
different cor ditions from anhydrite to gypsum and from gypsum back 
again to anhydrite, there may have been developed conditions both 
of pressure and of shrinkage, confined to the surface of the layers, 
and which might have had the effect of throwing the latter into 
wrinkles long prior to the operation of the more powerful pressures 
due to deformation, and which determined the larger foldings? Or 
can it be supposed that differences in the toughness and pliancy in 
the different layers, resulting possibly from the degree of hydration, 
may, during these larger foldings, have caused some beds to yield 
more readily than others, thus determining the effects observed? The 
two suppositions are opposed to each other, as one regards the 
minor wrinklings to have been determined before and the other after 
the deposition of the beds had ceased; but the occurrence of faults and 
unconformity, confined to certain layers, would seem to indicate that at 
various times in the course of that deposition shearing agencies were at 
work. The question is one full of difficulties, but whatever the explana- 
tion, the effects produced are certainly of a most singular and unique 
character. 
