Wm. F. Prouty — Meso-Silurian Deposits of Maryland. 567 



have a general trend N. 20°-30° E. There are six such folds 

 exposing these strata in Maryland : three in Allegany County 

 and three in Washington County (see map, fig. 1). The axes 

 of the anticlines are formed by the very resistant "Tuscarora" 

 or "white Medina" sandstone. Nearly all the folds are un- 

 symmetrical, giving a much narrower outcrop on the west than 

 on the east side. 



General Character of the Deposits. 

 Clinton Formation. 



The rocks of this age in Maryland consist essentially of red- 

 dish and olive to grayish and brown argillaceous shales which 

 are slightly lighter in color and less fossiliferous toward the 

 bottom. The exposed surfaces of this shale often show a deep 

 scarlet color. Thin sandstone bands occur at irregular inter- 

 vals throughout nearly the whole formation and become more 

 numerous toward the bottom, giving the formation the appear- 

 ance of grading into the Tuscarora quartzite. These thin sand- 

 stone bands were in general originally more calcareous than at 

 present and are uniformly more fossiliferous than the shale in 

 which they occur. Toward the top of the formation limestone 

 bands become numerous and replace the sandstone layers. They 

 seldom exceed six inches in thickness, and in some localities 

 are very f ossiferous. Immediately overlying the limestone- 

 bearing shales throughout the region there occurs a quartzitic 

 sandstone, of variable thickness, which in character resem- 

 bles very closely the Tuscarora. This sandstone thickens 

 markedly toward the east, increasing from ten feet in thick- 

 ness near Cumberland to nearly seventy feet in some eastern 

 exposures. In the top portion of this sandstone is found the 

 so-called top Clinton iron-ore, usually not more than a foot in 

 thickness and commonly of too low a grade to work. In places, 

 however, it is thicker and has been enriched so that in the 

 past it has served as an ore and might at present locally be so 

 called were it more accessible to the railroad. In this latter 

 respect the top Clinton ore differs markedly from the so-called 

 bottom Clinton ore which occurs throughout the Maryland 

 area from one hundred and twenty to one hundred and sixty 

 feet from the bottom of the formation and which, though it 

 sometimes attains forty feet, in thickness, is not sufficiently 

 high in iron to be valuable as an ore. This lower iron sand- 

 stone occurs in two beds separated by from six inches to six 

 feet of olive shale. Both the bottom and top "ore" bodies 

 contain numerous though very poorly preserved fossils. 



The olive shales and thin crystalline limestone bands imme- 



