﻿W. S. Shaler — Geology of Cobscooh Bay District, Me. 45 



believed that the deep sea deposits have more continuity of 

 structure, i. e., are less divided into layers, than those found 

 near the shore. This is probably the case with the strata formed 

 in many parts of the sea ; still we know that the Devonian black 



Fig. 8. — Section on Pembroke River, Cobscook Bay. A, massive trap 30 ft. 

 thick. B, B, B, sandstones and shales. C, C, C, thin ash beds. 



Fig. 9 — Section 3 miles N.W. of Red Island. A, massive trap. B, B, red sand- 

 stone and shale. C, breccia, probably volcanic. D, irregular ash bed. E, vermi- 

 form concretions in sandstone (Scolithus tubes). 



shales of the Ohio Yalley termed in the Kentucky reports the 

 Ohio shale, have a remarkable amount of stratification planes, 

 though they were certainly formed in deep water in a position 

 remote from the shore. We also know that any such disturb- 

 ance as would be produced in the deep seas by an earthquake 

 shock, would certainly cause a movement of the mud of the sea 

 floor, thereby bringing about the formation of a stratification 

 plane in the deposit. As this region was much subjected to 

 volcanic action at the period when these sediments were deposit- 

 ing, we may well believe that earthquakes were common in this 

 portion of the sea floor. 



The great preponderance of siliceous and shaly beds and the 

 remarkable absence of limestones in this district is a note- 

 worthy feature. It is probably due in the main to the singular 

 absence of corals and the infrequency of brachiopods and 

 crinoids, which groups were the principal lime producers of 

 the Paleozoic seas. 



All the evidence goes to show that these rocks of the Cobs- 

 cook series we*e in the main formed in water of moderate 

 depth under circumstances, which, owing to some causes, were 

 not very favorable to the development of organic life. In the 

 latter regard this district is in striking contrast with the basin 

 of the St. Lawrence, where during the same periods the seas 

 contained a singularly abundant life, as is shown by the Upper 

 Silurian deposits of the Island of Anticosti. I venture to sug- 

 gest, as a possible cause of this peculiarity, the fact, that this 



