ETNA-MONROE SYSTEM. 137 



whole has some of the characteristics of a fan-shaped delta. A plain of 

 marine clays extends from this point eastward to the Penobscot River. 

 Between this gravel plain and South Newburg, 2 miles distant, there are 

 several small low ridges or plains of rather fine gravel, which fact favors 

 the conclusion that during the final melting there Avas a limited overflow 

 from the larger plain (then a glacial lake) eastward into the arm of the sea 

 which then occupied the valley where now is South Newburg. South of 

 the delta-plain above mentioned lies a region of valleys and low hills. The 

 glacial gravels cross these as a series of broad ridges, separated by gaps, 

 which soon expand into a pretty large jjlain, about 2 miles long and three- 

 fourths of a mile wide. Along one part of the plain is a ridge rising above 

 the rest of the plain. This ridge expands in places into reticulated ridges 

 inclosing deep kettleholes. Bordering this ridge, which is composed chiefly 

 of large pebbles, cobbles, and bowlderets, is the rather level plain of finer 

 sand and gravel. Evidently the central ridge was deposited in a channel 

 between ice walls. The bordering plain is a delta, deposited either between 

 ice walls in a glacial lake or in the sea. This plain is situated east and 

 northeast of Monroe Village, and the Monroe Fair-ground is situated on it. 

 Marine clays widely cover the valley of Marsh Stream to a jjoint far west 

 of Monroe. South of Monroe Village the gravel takes the form of lenticu- 

 lar ridges or elongated domes. From this point south the gaps are a very 

 regular and constant part of the system, and they do not seem to depend 

 on the surface features of the land for their distribution ; at least if there be 

 such a dependence it is not easily detected. The system extends southward 

 through Monroe, crosses a low divide in Swanville, skirts the western side 

 of Groose Pond, and then takes a neai'ly straight course to Belfast Bay, near 

 the line between Belfast and Searsport. South of Goose Pond the system 

 for some nfiles takes the form of a low plain one-eighth to one-fourth of a 

 mile broad. The material becomes finer on the south, and is a delta-plain, 

 laid down prpbably in a bay of the sea inclosed at the sides by glacial ice. 



The gaps between these separated gravel deposits are not due to ero- 

 sion, unless locally here and there at the crossing of streams, but the gravel 

 was deposited discontinuously in this way. Between the separate deposits 

 lie undisturbed till or marine clay. 



The length of the system, from Stetson to Belfast Bay, is about 35 miles. 



