620 WALTER R. BERGER 
of the Fort Scott limestone. The records have been studied 
carefully and the top of the Fort Scott limestone determined by 
means of ‘‘spiderweb” cross-sections made from several thousand 
well records scattered uniformly from the locality of the outcrop on 
the east, westward past the edge of the area. 
The interval between the Boone chert and the Fort Scott lime- 
stone, i.e., the thickness of the Cherokee shale and Fort Scott 
limestones, at their outcrop near Pryor Creek, Oklahoma, has been 
determined as being 500 feet. This is considerably less than has 
been given heretofore for this interval, but the measurements have 
been carefully checked by three parties and the results are in 
substantial agreement. . 
From a study of the isobathic lines it will be observed that the 
greatest intervals recorded between the Fort Scott limestone and 
the Boone chert are in a northeast-southwest line from Labette 
County, Kansas, to Rogers County, Oklahoma. The interval 
becomes smaller both to the east and to the west of this line. 
In this connection it is interesting to note that the thickness 
of the limestone in the Fort Scott formation averages 20 to 40 
feet on the outcrop and thickens rapidly westward to an average 
of 80 to 100 feet in northeastern Osage County, Oklahoma, and 
southeastern Chautauqua County, Kansas. Thence the formation 
thins to the west until it can scarcely be recognized in the well logs 
in west central Osage County, Oklahoma, and western Chautauqua, 
Elk, and Greenwood counties, Kansas. The alignment of greatest 
limestone thickness in the Fort Scott formation parallels the 
northeast-southwest alignment of greatest interval between the 
Boone chert and the Fort Scott formation. 
The greater thickness of the Cherokee shale along the line from 
Labette County, Kansas, to Rogers County, Oklahoma, as shown 
by the isobathic lines, is interpreted as indicating the deeper part 
of the depositional basin in which the Cherokee was deposited. 
The lowest beds in this portion of the basin do not appear to have 
been deposited in the areas to the east and west, which were prob- 
ably either land or covered intermittently by shallow water. It is 
only in this deeper part of the basin that we have the thick, lentic- 
ular sands, such as the Bartlesville, Burgess, and Tucker, which are 
