44 



Fragmentary Lime Rock Strata. 



Section of Rock Strata on Will's creek. 

 Direction pf strata, E. and W. — rPosition, nearly horizontal. — Order, ascending 



Fiff. 6. 



Bed of the Run. 



1. Coarse, calcareous, mill stone grit, or fine Breccia, in beds of 

 about a foot in thickness. This rock is composed altogether of 

 comminuted, and generally rounded grains of different colored lime- 

 stone, from the side of a very large pea to that of fine sand. They 

 are strongly cemented by carbonate of lime, with a little iron, which 

 makes a very firm cement. The color of the grains is generally 

 light ash, and a dirty blue. Where the component grains are fine, 

 the sparry cement gives it the glimmering look of siliceous sandstone. 

 From its great resemblance to the Laurel hill mill stones, which are 

 siliceous, the neighboring inhabitants have manufactured it into stones 

 for their mills, especially for the grinding of wheat — very good flour 

 is made from these stones, but they need dressing often. When 

 used a few days, the surface of the stone, between the furrows, takes 

 a fine polish — shewing the imbedded grains of lime, similar to a 

 Breccia. This deposit rests on a stratum of common grey lime- 

 stone, which forms the channel of the run below. At the spot 



