LIMITED OCCURRENCE OF CIRQUES 293 



noticeable change of grade or inequality of surface. A small brook which 

 heads in a ribbon cascade on the headwall courses slowly along the floor. 

 There is no pond here like Hermit Lake, in Tuckermans Eavine, or 

 Spaulding Lake, in the Great Gulf. It is hard to imagine a local glacier 

 abandoning this ravine at the close of the Glacial period and leaving its 

 floor so perfectly free from morainic ridges or knolls. The cirque cutting 

 evidently antedates the last regional glaciation. The block pile at the 

 head of Jobildunk Eavine, like those in the Mount Washington ravines, 

 appears to be freshly quarried englacial drift, dropped by the ice-sheet, 

 together with rockfall debris of the period of deglaciation. 



One is disinclined to accept Jobildunk Eavine as an ancient cirque, 

 because it exceeds in size most of the Mount Washington ravines, although 

 it lies on the flank of a mountain only 4,810 feet high, and because the 

 ravines around Mount Lafayette (5,269), as already stated, seem to be 

 little altered, if at all, by local glaciers. Two factors may perhaps recon- 

 cile the apparent inconsistency: (a) The area above 4,000 feet on Mount 

 Moosilauke, though somewhat smaller, is much wider in an east-west 

 direction than that on the Lafayette Eange. The chance for snow to 

 collect in the ravines on the leeward (eastern) side of the mountain is 

 therefore greater on Moosilauke than on Lafayette, (b) The develop- 

 ment of a headwall depends largely on the condition of jointing at the 

 head of a ravine. It is possible that the quarrying out of the rock-masses 

 from the head of Jobildunk Eavine was more favored by the attitude and 

 number of joints there than on the side of Mount Lafayette. These 

 factors might compensate for the difference in height of Lafayette and 

 Moosilauke, which, after all, is only about 450 feet. 



The ravine on the northwest side of Moosilauke, which is skirted by the 

 Benton trail, is wider and rather funnel-shaped at its head, but lacks the 

 U-shaped cross-section and the steep headwall of Jobildunk Eavine. So 

 far as known, therefore, the local glaciation of Mount Moosilauke seems 

 to have been limited to the single glacier on its eastern side. 



From these scattered, yet related, observations it appears probable, as 

 in 1912, that the local alpine glaciers of the White Mountains were very 

 short, occupying only a few of the more favorably situated ravines, and 

 that they completed the development of cirque forms before the last or 

 southeastward passage of the ice-sheet over the region. 



Conclusion 



Assembling the conclusions reached through field-work on and around 

 the Bethlehem moraine, the Carroll outwash deposits, the special features 

 of the Ammonoosuc Valley, and the ravines on the neighboring summits, 



