GEOLOGY OF MOUNT DESERT. 69 



But at the closing stages of the ice invasion and for a time 

 afterwards, the land must have stood lower than now ; for 

 beds of stratified clay bearing marine fossils are found at 

 various points on the lowland of the Island and the main- 

 land, up to about two hundred feet above the present sea 

 level. Judging by the relation of these clays to the washed 

 gravels and sands on the higher slopes, it is probable that 

 the submergence about the close of glacial time amounted 

 here to at least three hundred feet. The clays are relatively 

 scanty on the southern side of the Island ; they are exposed 

 above the shores of Wasgatt Cove, near the Narrows of 

 Somes Sound, and in Seal Harbor. On the northern low- 

 land, they have a wide extension, and conceal the rocky 

 floor over much of the district. On the mainland, the 

 clays and sands are so plentiful over the coastal lowland 

 that they greatly diminish the ruggedness of the rolling 

 foundation on which they lie ; and they efficiently aid the 

 deposits of till in displacing the rivers from their preglacial 

 courses. 



During the depression indicated by these stratified de- 

 posits, Mount Desert was not a single island, but a row of 

 imperfectly connected mountains. Somes Sound was then 

 a thoroughfare, and had several fellows on either side. 

 Nearly all the lower stretches of the Island were sub- 

 merged. Not only so ; at that time the scanty remnants 

 of rocks other than the granite, now visible in patches 

 along the shore, must have been entirely concealed beneath 

 the sea. The geological structure then visible would have 

 been extremely simple. 



The depression of the land about the close of the glacial 

 period cannot have been maintained long at any one level, 

 for nowhere on the slopes of the island are there shore 

 lines of as great distinctness as those which mark the 

 present margin of the sea. A depression of much more 

 than three hundred feet has been inferred by Professor 



