DEAD EIVER-JEEUSALEM SYSTEM. 187 



greater breadth tlian usual in such a situation. The valley of Purgatory 

 Stream to the northeast is from one-third of a mile to more than a mile in 

 breadth. The appearances are as if the valley was occupied by a local 

 tongue of ice which continued its' motion while the gravel plain was being 

 deposited. If so, the space between the front of the ice and the hill to the 

 south woidd be occupied by a broad glacial stream, or by a lake, and the 

 osar-plaiu may in part partake of the nature of a water-washed terminal 

 moraine. 



The system evidently dates from a late period of the Ice age, since 

 the marine delta near its southern extremity is situated so far from the 

 present coast. 



LOCAL ESKERS IN NORTHWESTERN MAINE. 



Horseback at Leadbetter Falls. — Tliese falls are situated ou the Penobscot River 

 near its source. Prof C. H. Hitchcock describes a ridge, presumably of 

 glacial gravel, as follows: "At the farther end of the portage is a large 

 horseback, which terminates here in a ledge larger than the ridge itself. 

 We traced this horseback up the river for 3 miles, and found it was not 

 parallel with the river itself"^ 



pariin Pond horsebacks. — Professor Hitclicock also descnbes a horseback near 

 Parlin Pond, as follows: "Northwest from Pariin Pond there is a curving 

 horseback three-fourths of a mile long."^ I am informed that there is 

 another similar ridge northeast of the pond, near its outlet. 



Kibby stream horseback. — A two-sided ridge, probably of glacial gravel, is 

 reported by Mr. A. J. Lane, of Lexington, and others as being found 

 between Spectacle Pond and Kibby Stream, which flows into Dead River 

 at Grand Falls. 



DEAD RIVER-JERUSALEM SYSTEM. 



From the great bend of the Dead River in Dead River Plantation, a 

 very low valley extends southward past the east base of Mount Bigelow. 

 Bog Brook takes its rise near the highest part of this pass and flows slug- 

 gishly northward to the Dead River. A ridge of sand and gravel begins a 

 short distance south of Dead River and follows the valley of Bog Brook. 

 It forms a natural roadway through a low level region near the axis of the 



' Second Annual Report npon the Natural History and Geology of the State of Maine, p. 345, 1862. 

 'Ibid., p. 3Si9. 



