348 The American Geologist. Jane, 1895 
call for no special comment here. The others may be briefly 
noticed. 
Foravi ill/feral Limestone. — This rock has a fairly constant 
petrographical character although it occurs in at least two 
horizons. The lower and more persistent and voluminous of 
the two formations is nearly pure limestone; the upper con- 
tains a notable proportion of clay. There are several hundred 
feet of sandstone and other rocks between the two formations. 
In general it is a very compact rock resembling lithographic 
limestone. Its color is a light drab gray to dark gray. The 
rock is generally traversed by minute veinules of calcite inter- 
secting in all directions without evidence of faulting, and by 
larger veins of dark-colored silica, usually an inch or two 
thick, traversing the rock pjirallel to the bedding, with occa- 
sional transverse veins. The Foraminifera are represented 
by clear hyaline spots ranging in size up to .5 mm., which, 
in favorable cases, may be observed with the lens to have the 
forms of shells. In thin section the limestone is a structure- 
less cryptocrystalline aggregate which between crossed nicols 
appears light, whitish gray, due to compensator}^ polarization. 
The sections afford no evidence of deformation nor are the 
Foraminifera deformed by dynamic action. The latter are 
quite discrete from the matrix in which they are imbedded. 
The rock appears to be a chemical deposit in which Foramin- 
ifera were more or less sporadically entombed. 
Badiolarian Cherts. — These are hard, flinty, siliceous rocks 
of a prevailingly brownish red color. Yellow and green 
colors are not uncommon, however, and other colors are more 
rarely met with. The most remarkable feature of these cherts 
is their bedding. This is well displayed in numerous favor- 
able sections. The essential feature of the bedding is the 
alternation of thin sheets of chert with partings of shale. 
The sheets of chert range generally from one to three or four 
inches in thickness, with an average of perhaps two or three 
inches. Occasionally there are thicker beds. The shaly part- 
ings vary usually from about one eighth to one half an inch 
in thickness. As the sections are in places several hundred 
feet thick they present the remarkable phenomenon of an 
alternation of thousands of these chert sheets with the corres- 
ponding layers of shale. 
