LIMESTONE. 125 
of Washington, where it reaches a thickness of nearly 30 feet. The 
tunnel of the Baltimore and Ohio Railroad, 1 mile east of town, cuts 
through the bed, exposing at its west end the section given below. 
The limestone is quarried at this place. 
Section of Upper Washington limestone 1 mile east of Washington. 
Ft. in. 
Limestone, blue-black 2 3 
Shale, black 2 
Limestone, blue-black 10 
Shale 4 
Limestone, blue-black, brittle 1 10 
Shale, black 2 2 
Limestone, hard, gray, and thin shale 5 4 
Shale, soft, dark S 
Limestone, light brownish gray, very hard, to level of railroad 3 6 
16 11 
On Cemetery Hill, in the southwestern part of Washington, just 
off the quadrangle, a section of 19 feet exposed in an old quarry is 
made up of a great many thin beds of alternating limestone and shale. 
The detailed measurement of an average section here is as follows : 
Section of Upper Washington limestone on Cemetery Hill, Washington. 
Ft. in. 
Limestone, gray-brown 1 
Shale, soft, black 1 
Limestone, hard, blue-black 2 5 
Shale, black 4 
Limestone, brown-gray 11 
Shale, soft, black 2 
Limestone, blue-black 1 8 
Shale, black 1 1 
Limestone, compact, brown-gray 3 
Shale, yellow 1 
Shale, hard, black, slaty 2 
Limestone, brown 10 
Shale, light brown 2 
Limestone, hard, brown 2 2 
Shale, soft, dark 4 
Limestone, hard, brown 4 
Shale 3 
Limestone, hard, brown 1 8 
Fire-clay shale, dark 1 
Limestone, brown-gray; bottom of quarry. 
18 9 
