48 GLACIAL GRAVELS OF MAINE. 



could be concentrated into beaches at right angles to the shore. The rains 

 easil)^ penetrate the beach gravel, until they reach the more impervious 

 till; they then seep along the top of the till in the gravel, and escape as 

 small springs at the beach cliffs. The till is compact and clayey, and con- 

 tains great numbers of scratched stones. It appears to differ in no impor- 

 tant respect from the till found in the mainland north of this island. 

 Ragged Island is more diversified by hills, and the till has been denuded 

 from the southern slopes of the hills and drifted into the valleys, forming 

 one or more plains of beach gravel extending across the island from south 

 to north, as at Monhegan. 



Isle an Haut is about 7 miles long from northeast to southwest, and 

 about 2 miles broad. Its eastern and southern sides are exposed to the 

 open ocean. On account of the number of fallen trees and the density of 

 the scrub forest, the island is difficult to explore and it is impossible to get 

 any general view of the old beaches. Near the southwestern extremity of 

 the island I traced a line of beach gravel up a valley to a height of 225 

 feet by aneroid. Here the rolled gravel suddenly disappeared, and above 

 that elevation only ordinary till could be found. Guided by the barom- 

 eter, I then went nearly around the island at this elevation, and at every 

 valley found rounded gravel and bowlders up to 225 feet, at which eleva- 

 tion the rolled gravel began to thin out, and the contour of 250 feet was 

 plainly above the Avater-washed drift. From that elevation to the top of 

 the highest hill (550 feet) not one water-washed stone could I find, though 

 they were very abundant and easily found below. On the projecting angles 

 of the hills (wliich would be capes with the sea standing at high levels) 

 the till was extensively denuded. No cliffs of erosion were observed above 

 the present beach. 



Similar observations were made near Southwest Harbor and at many 

 other points on Mount Desert Island, also at many favorable places on the 

 mainland. One of the most accessible places for examining the highest 

 beach is about 3 miles northwest of Rockland, in the valley of Chicka- 

 waukie Stream and Lake. This valley is bordered on the west by a high 

 hill or ridge, rising 400 feet or more above the sea. For several miles 

 along the southern and eastern base of this hill rolled gravels are abun- 

 dant. In places the gravel takes the form of a distinct terrace on the 



