[BAILEY] THE GYPSUM OF ALBERT COUNTY, N.B. 123 
directly upon the abruptly cut edges of another set, with an angular 
discordance of 30° or more between the two, while both have been 
subjected to shearing and faulting. The compression indicated by the 
more regular foldings or frills would be about one-fifth of the original 
leneth. Examples of the faultings may be seen in Plate II. 
What explanation can be given now of these various conditions? 
Lateral pressure at once suggests itself as the most probable cause of 
the larger crumplings which differ in no way from those produced in 
other rocks as the result of deformation subsequent to the deposition 
of the beds. It is also well known that where flexible beds, like 
shales, lie between others, like quartzites, which are hard and unyield- 
ing, the softer beds may exhibit numerous and complicated plications 
which are not shared with them by the firmer deposits between which 
they are enclosed. But usually such plications are of the most irregular 
character, whereas, in the present instance, as has been stated, the finer 
corrugations show all the symmetry and regularity of an artistic design, 
and that too involving different patterns in layers not more than an 
inch apart, while layers apparently equally fine and flexible and in 
general position parallel with the latter, show no such subordinate 
plications whatever. And if it is difficult to understand how such a 
structure as that represented in Plate I. where a single layer has been 
so strangely plicated without any evidence of such movement in the 
enclosing layers, though the folded layer be not more than half an inch 
in thickness, could be produced, what are we to say regarding that 
illustrated in Plate II., where another layer, again of inconsiderable 
thickness, is conspicuously serrated or dentelated upon one side while 
the opposite side is flat and the mass of the layer is destitute of any 
evidence whatever of movement? From the structure in this case and 
from the relations of rectangularity to the general stratification ex- 
hibited by the more conspicuous frillings, even when the beds as a 
whole are crumpled, one is almost led to think that the cause, what- 
ever its nature, which determined these subordinate structures operated 
prior to and independently of those determining the larger foldings. 
It must be remembered in this connection that anhydrite, in the 
course of its conversion into gypsum, undergoes as the result of the 
absorption of water, a very considerable increase of volume (about 60%) 
and that this would cause lateral pressure confined to the layer or 
layers in which the hydration was going on; also that under varying 
conditions of temperature, salinity, etc., very slight variations in 
conditions might lead to very different results as regards the tenacity, 
plasticity, etc., of the forming beds. May it not have been the case 
that as the materials which now form the gypsum deposits were being 
slowly laid down in shallow basins, alternately exposed to submergence 
