282 GLACIAL GEAVBLS OF MAINE. 



where all the vigilance of road overseers and selectmen exercised for years 

 has not succeeded in finding- a- wagon load of genuine water- washed gravel. 

 4. Ai-e the drumhns remains of a former sheet of till irregularly eroded 

 by the glacier"? I do not know how a glacier can deposit till and not at 

 the same time also deposit glacial gravel. Glacial streams are inseparable 

 from a glacier. The work of the latest ice-sheet is a fair sample of what 

 former ice-sheets did, differing only as they have differed in size or time of 

 continuance. Now the latest Ice period has left hundreds of square miles 

 covered with well-rounded stones and bowlders distributed over a large 

 part of this State, as well as of New England generally. If at any future 

 time Maine is again glaciated, those rounded stones will be incorporated in 

 the till or pushed bodily out into the Gulf of Maine, being more or less 

 changed in shape during the process, but still being quite different in form 

 from angular stones of fracture. It is possible to conceive of glaciation so 

 severe as to remove all the glacial gravels from Maine into the sea, but 

 farther west, where the outer terminal moraines are deposited on the land, 

 the water-rounded stones of the last ice-sheet would appear in the moraines. 

 If any one claims that the lenticular hills are remains of the till of a former 

 Ice period that failed to be eroded by the latest invasion of the ice, on 

 him rests the burden of proving that the till and terminal moraines of 

 southern New England contain a sufiicient number of once rounded stones 

 and bowlders to account for the glacial gravels of such supposed more 

 ancient ice-sheet and which the later ice incorporated into its own deposits. 

 Of course it is assumed that if a sheet of till can be eroded by ice, masses 

 of sediments would sooner be eroded. For the present the theory under 

 examination can not be insisted on. 



RELATION TO MARINE GRAVELS. 



The relation of the lower till to the beach gravel deserves notice in 

 this connection. 



A good place for study of the subject is at Matinicus Island. A 

 lenticular mass of till 10 to 50 feet deep covers the western portion of the 

 island, as is proved by the cliff of erosion at the present beach and by 

 wells. The till is everywhere covered by a few feet of beach gravel. The 

 till is very fine in composition, is very compact and intensely glaciated, has 

 a dark-blue color, and is typical lower till, very different from the matter of 



