96 CEMENT MATERIALS AND INDUSTRY. [bull. 243.1 
1 inch to a foot or more in thickness, intercalated with like irregular"] 
layers of chert; in other places it occurs in lenticular masses; again,! 
the chert occurs in lenticular or nodular masses in the limestone; in ) 
still others the chert and limestone are so intimately diffused that it< 
is not possible to draw any sharp line between them. It often hap-] 
pens, however, that the limestone forms a bed from 20 to 100 feet or j 
more in thickness, almost or entirely free from chert. It is in such 
places that the stone acquires an economic value. The variability o: 
the Boone formation is largely due to local causes favoring or retard 
ing replacement of limestone by chert. 
Nearly all the limestone in the chert is more or less crystallin 
but it is much more so in some places than in others. In a genera 
way it is more crystalline in the central part of the area than eithe 
to the east or west, and more crystalline in the east than in the wes 
While there are many local changes in color, texture, and structure 
of the limestone in the chert, there are some distinctly marked vari 
ties of it. 
Distribution. — The oolitic limestone, which is one of the most val 
able varieties, is known to occur at three localities: Northeast 
Batesville; near War Eagle Creek, about 4 miles north of Huntsville; 
and on Brush Creek, in T. 17 N., R. 28 W. The rock at Bates! 
ville a occurs in layers from 3 to 5 feet thick, and can be quarried in as | 
large pieces as can be handled. In color and appearance it resembl 
the Indiana oolitic stone somewhat, but is harder and more crystalli 
than most of the Indiana stone and is harder to work. The ston 
found at the two other localities mentioned above is lighter colored, 
softer, and more easily wrought. 
Another variety occurring in the western part of Independence 
County is a hard, compact, close-grained, finely crystalline, slightly 
fossiliferous, dark- colored stone, the dark color being due to bitumi- j 
nous matter, which in some places occurs only in such small quantities j 
as to give the stone a light-gray color. In some places it develops a 
shaly structure, but in most places occurs in layers from 2 inches to | 
feet in thickness, which are firm, solid, and resonant. 
A variety which is. widely distributed over the central part of the 
area is highly fossiliferous, coarsely crystalline, and varies from light 
to dark gray in color. The fossils are mostly crinoid stems, though.] 
the rock contains numerous bryozoans and brachiopods. In so 
places it contains considerable amorphous matter, but in many pla 
is almost completely crystalline. 
Composition. — The limestones in the chert vary greatly in composi 
tion, ranging by close gradations from chert to almost pure calciun 
carbonate. However, in nearly all places where the large beds o 
« According to Mr. E. O. Ulrich this rock overlies the Boone and belongs to the Moorefield shale. 
as 
