HETIOULATED ESKERS OE KAMES. 449 



"Roman theaters," many of which are so deep as to inclose lakelets without 

 visible outlets. 



Probably the phenomena of all the glaciated countries will have to be 

 compared before we are able to explain these interesting formations in all 

 their details. 



The most important facts concerning the reticulated ridges are the fol- 

 lowing : 



1. Their geographical distribution. The most remarkable of these 

 plains are situated in southwestern M^ine, where they are connected with 

 the Conway-Ossipee kame plains of New Hampshire. Almost all the osars 

 and other gravel systems here and there expand into a plexus of reticulated 

 ridges, but they are not large except in the granitic areas. The granite 

 outcrops of eastern Maine are much smaller than those of western Maine, 

 and the general slope of the laiad is not so steep. For these and perhaps 

 other reasons the reticulated eskers of that part of the State do not cover 

 so broad areas. 



2. Their relations to long gravel systems. The reticulated kames are 

 not a distinct class of systems, but a peculiar form into which the longer 

 gravel systems here and there expand. They were deposited by the same 

 glacial rivers that left the osars and other types of gravels. 



3. Their relations to relief forms of the land. All the longer gravel 

 systems at some part of their course pass from one basin of natural drain- 

 age to another, and most of them do so repeatedly. In the interior of 

 the State the areas of reticulated ridges into which the osars and broad 

 osars expand are rather small. They are situated variously with respect to 

 the slopes of the land, being found on both up and down slopes and in 

 level regions. Thus going up and over the hills and across the valleys, the 

 great river at last penetrated all the higher transverse ranges of hills along 

 the low passes and came out into a region of broad valleys which soon 

 merge into the sea-border plain, a roUing region extending 30 to 40 miles 

 from the sea. In the hill country the gravels usually take the form of osars 

 or osar terraces, but when they reach the broad valleys of gentler slope 

 they expand into great plains or tracts of reticulated ridges. These are 

 mostly situated between the contours of 230 and 500 feet. 



4. The forms of the ridges. In western Maine the ridges are usually 

 MON xxxiv 29 



