GEOLOGY OF^AEOOSTOOK COUJSÎTY, JIAINE. 43 



where the stream again turns to the east, and about half a mile below the mouth of a 

 small brook coming in upon the northern side, are bluffs of grey calcareous slate, interstrat- 

 ified with thin layers of grey sandstone, and holding also thin layers of dark-blue compact 

 limestone. They all lie at a low angle, and from this point, for a mile or more, exhibit 

 along the shores a series of undulations, in which the folds are, for the most part, very 

 broad and open, with very moderate dips (4" or 0°), but which also include some more 

 abrupt corrugations, with dips as high as 80'. The slates have a strong cleavage, with an 

 underlay N. 50 W. > 80", and have also a pale-greenish tinge, which, by weathering, 

 sometimes becomes quite pronounced. The limestone layers are from three-fourths to one 

 and a quarter inches in thickness, being separated from each other by about six inches of 

 slate, and where first seen form continuous sheets, but somewhat further down they 

 exhibit the remarkable peculiarity of being transversely and abruptly broken into separate 

 pieces, from one or two inches to a foot in length, as though the whole rock had been 

 shattered by the passage of violent vibrations — a feature which is exactly repeated in 

 similar beds, having similar associations, on Siegas River, in Victoria County, New 

 Brunswick. Much of what has been called limestone upon this river is really only a highly 

 calcareous slate, which weathers somewhat like the first-named rock, but there are also, 

 in places, numerous thin bands alternating with the slates, of nearly pure, dark-blue lime- 

 stone, seamed with spar. The last beds visible upon the stream are to be seen about 

 three quarters of a mile above the mouth of Salmon Brook, in Washburne, below which 

 the river is bordered by low banks and intervales. It is near this point that, in the fields 

 above the river, occurs the bed of iron-ore referred to by Prof Packard, in Hitchcock's 

 Report. This, not outcropping upon the stream, was not seen by the writer, but its posi- 

 tion would, apparently, correspond to that of the red and green slates, which are else- 

 where, both in Maine and New Brunswick, so generally associated with such ores. 



■ If now the above section upon the Aroostook be compared with that given in my 

 paper of last year, as seen on the East Branch of Fish River, it will be found that, if the 

 conclusions above stated are correct, there is between the two a very close correspondence 

 Thus, in the Fish River section, we have — 



Grey, reddish and brown sandstones and shales, associated with bed.s and enclosing masses of fos- 



siliferous limestone. 

 Grey calcareous conglomerate, with pebbles of dark ilinty slate, jitsper, etc. 

 Grey calcareous and buff-weathering sandstones, with crinoids and shells. 

 Grey and dark-grey slates, with remains of plants. 

 Grey, bluish-weathering calcareous slates. 



and upon the Aroostook — 



Grey, reddish and brown sandstones, containing fossiliferous calcareous layers, and associated 



with beds of highly fossiliferous limestone. 

 Green and red slates, with thin beds of calcareous conglomerate. 



Heavy beds of coarse conglomerate, with pebbles of black siliceous slate, green and red jasper, etc. 

 Grey sandstones, often buff-weathering, with numerous remains of shells and corals, mingled with 



fragments of plants, small pieces of black slate, and occasionally of serpentine. 

 Grey, dark-grey and greenish, calcareous slates, with thin bands of limestone, and beds of hema- 



titic iron- 

 Grey, bluish-weathering calcareous slates. 



