388 DESCKIPTIVE GEOLOGY. 



possibly be organic casts, biit, if so, are not definite enough to admit of 

 specific determination. 



Above the quartzite is a very large, heavy bed of limestone, 600 or 700 

 feet in thickness, which is much contorted, the dip-planes being in some 

 places entirely obscured by metamorphism and local twists, but, in general, 

 sufficiently developed to see that it is entirely confomiable with the under- 

 lying quartzites. In these limestones, a few ill-preserved fossils were found, 

 and are determined by Professor Meek to be distinctly Coal-Measure forms. 

 These beds, then, mark the base of the Upper Coal-Measure group. The 

 strike is north 16° east, or north magnetic. On the hill-slopes to the north 

 of the river, where they consist of cream-colored and gray, highly-altered 

 limestones, reaching almost the whiteness of marble, they curve westward, 

 up the ravine north of the upper tunnel, and are seen on the heights above 

 to be conformable with the diminished dip of the quartzites. South of the 

 river, they seem to be less altered and less contorted, and to possess a more 

 regular and heavier bedding. A mile or more up the hills, near where they 

 pass under the Tertiaries, they are seen to be interspersed with beds of pale 

 yellow, fine-grained limestones. Overlying these are a series of yellow cal- 

 careous shales, about 1 75 feet thick, very brittle, and whose surfaces, instead 

 of being smooth planes, are broken by little ridges and depressions, some- 

 what resembling ripple-marks, but wanting in their regularity. This is 

 doubtless a peculiar result of pressure, and the shaly weathering due to 

 the irregular surface of the crushed limestone. They are covered in many 

 places with a sulphur-yellow oxidation-product. Search yielded no fossils. 

 Above these calcareous shales are a series of sand and mud-rocks, chocolate- 

 and olive-colored shales, and red argillaceous sandstones, about 225 feet in 

 thickness. These are peculiar, as displaying the very finest ripple-marks, 

 the distance between the wave and trough being not over an inch to an inch 

 and a half; alternating chocolate and olive shales form the lower 200 feet; 

 the upper 25 feet being of a pretty solid sandstone. These are overlaid by 

 about 100 feet of yellow and olive shales, which decompose very easily, 

 and have a general earthy outcrop. Next in the ascending series are about 

 150 feet of gray-blue limestone, followed by about 20 feet of mud, hardly 

 compacted into rock, showing here and there thin seams, which are stony. 



