﻿iT. S. Shale?" — Geology of Cdbscook Bay District, Me. 39 



the main apparently composed of true lavas but at certain points 

 evidently composed of fragmental volcanic rock in the form of 

 ash beds and breccias. In their composition, in their attitude 

 and in their fossil contents they present many eminent pecu- 

 liarities. 



In the absence of any sufficient topographical survey of the 

 district it has not been found possible to prepare a geological 

 map which will represent even the more important features of 

 this structure. 



The following account is intended only to present the more 

 general facts which were determinable by a preliminary inspec- 

 tion of the ground. 



The first point that strikes the observer is that the expo- 

 sures of rocks of Silurian and Devonian age which are shown 

 in the Cobscook district, i. e. the region lyjng to the east of 

 Moose Island, have nearly uniformly eastern dips. The fol- 

 lowing table of these dips will show that in localities fairly 

 representing about one hundred miles of shore line in the 

 Cobscook series of bays, there is very little departure from this 

 uniform direction. It is also evident that the amount of this 

 dip is not great and is very regular; it rarely rises above 60° 

 and rarely falls below 20° of inclination. The few instances in 

 which the dip of the rocks departs decidedly from the general 

 easterly direction may be explained by local accident and do 

 not indicate any general change in the direction of the dip. 

 It should be said that the dips given in the table represent 

 about the average of over two hundred observations from which 

 the selection was made. 



Selected list of dips observed in Cobscook Bay. 



■ Locality. Strike. Dip. 



McMaster's Island N. 45° E. S.E. 10-60° 



Eastport Island, W. side K 45 W. N.E. 60. 



" " N. 60 E. N.W. 20. 



Reynolds Cove _ . _ N. E. 20-30. 



Pembroke River N. 10 W. KE. 30. 



Pembroke Neck, W. side IS". E. 20-30. 



" E. " N. 125 E. S. 17. 



" " « N. 110 E. S.E. 10. 



Dudley Island K E. 50-60. 



Pembroke River N. 45 W. N.E. 55. 



...... N. 45 N.E. 45. 



" " N". 130 E. S.E. 30. 



South of Seward's neck canal KE. to N.W. E. 10-30. 



South Bay K 50 E. E. 30-40. 



" " N. 45 W. E. 15-25. 



Straight Bay N. 40 W. E. 35. 



" N.40W. E. 35. 



