CALCAREOUS CONCRETIONS OF KETTLE POINT 137 
inches. The decomposition of the pyrites has led to the efflo- 
rescence of the usual sulphates of iron and alumina and of the 
hydrous oxalate of iron, humboldtite. 
The shale is nearly horizontal, well laminated and very fissile, 
the flakes of the rock being readily split out and piled up on 
edge by the waves, which thus build a curious belt of jagged and 
Fic. 2. Concretion and deformation of the shale. 
shattered fragments on the bed rock. The only other notable 
structure in the interconcretionary spaces is the universal occur- 
rence of two extremely perfect systems of vertical joints at right 
angles to each other (Fig. 1). These joints affect the shale 
only, and do not pass through the concretions anywhere, so far 
as I have had opportunity of observing the latter. 
The most striking structure in the shales is, however, the 
local departure from the normal horizontal position of the parts 
of the beds in the immediate vicinity of the concretions. In 
every one of the dozen well-exposed concretions still in place 
the strata are plainly arched over the upper hemisphere and bend 
