﻿]Sf. S. Shaler — Geology of Cobscook Bay District, Me. 49 



lar in appearance to those on Campobello abound about 

 Frenchman's Bay, and at other points to the westward. 

 Wherever these rocks occur it seems to me there is reason to 

 hope for some traces of the overlying Cobscook series. 



One of the most difficult problems in the section is to deter- 

 mine the relations of the Perry series of sandstones and con- 

 glomerates to that of Cobscook Bay ; at no point as yet has the 

 former series been found in contact with the latter. But in 

 the valley of Sipps Bay we find a series of red shales and 

 sandstones, which has a thickness of over fifteen hundred 

 feet, and probably belongs to the Perry series. These beds 

 Jiave the same general dip as those of the Cobscook series, 

 where the latter series is shown about a mile farther to the 

 south. It ,is likely that -a careful search in this part of the 

 field may reveal a contact of these two sets of beds. 



On the mainland just north of Moose Island, and thence up 

 to the town of Perry, similar sandstone and conglomerate beds 

 are shown, with a strike which would place them above the 

 beds of the Cobscook series of that island. But in this Perry 

 district the section of red shales and sandstones lies apparently 

 on the denuded edges of the granitic and s}^enitic rocks which 

 form a yet lower series than those which furnish the floor of the 

 red conglomerates and shales of Deer Island. That is to say, 

 while the Perry series of Deer Island lies on the old slates 

 of the Campobello series, in the more northern exhibition of 

 the beds they are directly on the rocks of presumably Lauren- 

 tian age. The Perry series of rocks appears to be much less 

 cut up by dykes than the underlying Cobscook series ; no intru- 

 sions of igneous matter were observed in the outcrops which 

 were studied. This makes it probable that the time of most 

 intense volcanic action had passed away before the Perry series 

 was deposited. 



Thus this district seems to contain the following more or less 

 well indicated series of stratified rocks. At the base a series 

 whose thickness is unknown, consisting of gneissoid syenitic 

 and granitic rocks and some mica schists ; of this series little 

 is known : it is the prevailing series of crystalline rocks along 

 the coast of Maine, and is probably of Laurentian age. 



Above these series lies a second which for convenience we 

 have termed the Campobello group, comprising a set of dark 

 greenish and grayish siliceous and argillaceous rocks contain- 

 ing very little lime. 



This Campobello series has a thickness of at least four thou- 

 sand feet and may be thicker; the rocks appear to be entirely 

 destitute of fossils though they are not so much metamorphosed 

 as necessarily to lose by this change all trace of fossils if they 

 had once contained them. This section may be equivalent to 



Am. Jour. Sol— Third Series, Vol. XXXII, No. 187.— July, 1886. 

 4 



