140 REGINALD A. DALY 
interesting than the interior of the already shattered ‘‘kettles.”’ 
It is said that the concretions may be seen on the bottom - 
in the very shallow water of the lake five or six miles from 
Kettle Point, and that specimens may be readily fished from the 
bottom as much as two miles from the shore, where they have 
been leached out by the erosive action of the larger waves. 
Fic. 5. Large concretion in place; the shale in its immediate vicinity exhibits 
slaty cleavage developed tangentially to the concretion. 
Composing as they do such a comparatively large proportion of 
the rock, and occurring in similar profusion in the Upper Devonian 
of Michigan and Ohio, it is hardly just to say, in the words of 
Dana, that radial spherical concretions are ‘‘ of inferior geological 
importance.* 
A chemical analysis of one of the darker tinted brown con- 
cretions was made, and yielded the following percentage com. 
position : 
*Manual of Geology, 4th ed., p. 97. 
