HAWORTH AND BENNETT.| General Stratigraphy. 103 
operated extensively a few years ago, obtained their material 
from the Allen limestone. Here the crystallization was car- 
ried to a high degree, sufficient to make almost the entire mass 
of the rock crystalline, but not so as to destroy its fossils. 
Fauna.—The fauna of the Allen limestone is particularly in- 
teresting on account of its carrying so many fossil sponges 
where it is exposed to the surface from Chanute southwest- 
ward. These sponges are unusually numerous and well pre- 
served, making quite a characteristic feature. 
Vilas Shales.48 
The name Vilas shales is here used to designate the shale 
lying just above the Allen limestone and below the Stanton. 
When the name was first suggested by Adams its exact appli- 
cation was not clearly defined because the position of the shale- 
bed was not then fully determined as regards limestones above 
and below. Adams thought that the Iola limestone extended 
southwestward, capping the hills at Neodesha, and that, there- 
fore, the Vilas shales lay under the Iola. In this particular 
area he mistook the Allen for the Iola. Later he saw his mis- 
take, and corrected it in United States Geological Survey Bul- 
letin 238. 
The shale-bed about Vilas to which he attached the name is 
now known to lie on top of the Allen limestone, its outcropping 
forming a narrow zone extending practically across the state, 
except where cut off by the tying of the limestone above and 
below it. 
Thickness.—The Vilas shales vary greatly in thickness. At 
one point south of Vilas they are about 125 feet, and the out- 
cropping line of the overlying limestone is carried back west- 
ward fully five miles from the outcropping line of the underly- 
ing limestone. To the southwest it thins rapidly and on the 
south bluffs of Fall river at Neodesha has a thickness of a little 
more than 5 feet. Still farther south it so nearly disappears 
that the two enclosing limestones practically become one and 
it can scarcely be distinguished at the south line of the state. 
To the northeast of Vilas the thickness decreases to about 10 
feet, which diminishes to 5 feet at the Kansas river. Through- 
out the greater part of the distance northeastward from Gar- 
nett the Vilas shales are so thin that the enclosing limestones 
form one escarpment and may be considered as one. 
48. Adams, Dr. George I.: Univ. Geol. Surv. of Kan., vol. 111, p. 51. Lawrence, 
1898. 
