Geology of Seis'eca County. • 93 



miles south of Waterloo. Following the stream downward 

 toward the limestone we find (in descending order), 



1. The usual black shale (? 20 feet). 



2. Crossing the road, eastward, a foot of hard limestone. 



3. Blue-black shale, finely jointed, with immense numbers of 

 Liorliynchiis limitaris, and some Styliola fissurella^ a few trilobites 

 and orthocerata. Large concretions. 



:t. Yery black shale, sooty in look, with whitish deposit (sul- 

 phate of iron); delicate fossil impressions, in part gilded with 

 pyrite. A very fine grained, tough, nonfossiliferous limestone, 

 two and one-half laches thick, divides this shale in two. 



After losing the exposure for some distance, limestone appears 

 in the bed of the brook, in three tiers ; the upper two 11 and 4 

 inches ; the lower can not be measured. Upper surface marked 

 with slender curving light streaks, probably of concretionary 

 origin, an inch or two in length; lower tier with hornstone. 



This section is typical of the base of the Marcellus in this 

 region. The divisions 3 and 4 could not be measured, but repre- 

 sent only a few feet each. 



The thickness of this formation is suggested in several ways. 

 At the northeast corner of Seneca lake it forms the whole base 

 of the hill and rises probably 70 feet along the hill side. The 

 large hill farther south rises 200 feet above the lake ; its west- 

 ward foot in the lake displays cliffs of this rock 30 feet high ; its 

 eastward slope of 50 feet is of the same rock. 



Two stretches of cliff, previously mentioned, are found along 

 the lower part of Seneca lake, which, with Kendig's creek, form 

 the chief exposures of the Marcellus shales. The belt of country 

 covered is from three to six and eight miles wide — the latter 

 being the distances between extreme exposures on the lake fronts, 

 where for geometric reasons the exposures are prolonged. 



Hamiiton Shales. 



This division comprises two thin beds of limestone and four 

 shales, as follows, beginning ^t the lowest. 



1. Transitional shale. 



2. Basal limestone. 



3. Olive shale. 



