A. C. Lane — White Mountain Physiography. 351 



morpliosed zone was not mncli higher. Thus, during the 

 Mesozoic, when erosion went on with little local differen- 

 tial uplift or disturbance when the sea rose (Barrell says 

 to 2450 feet A. T.), the Paleozoic White Mountains were 

 reduced to ridges in hard rocks, well below timber line, 

 in fact, not much over 4000 feet above the level of the 

 Cretaceous sea. If we go back into the mountains and 

 look, not for the heights of the old surface, but for the 

 lower parts as near as possible to the old sea-level line, 

 low gaps and necks not likely to have suffered much since, 

 we find, besides some '' shoulders" or ^4awns" between 

 5000 and 4000 feet, of which I shall write later, many on 

 Cutter's 1918 map of the Appalachian Mountain Club 

 not far from 3000 feet. I had picked out Maple Moun- 

 tains, 2635 feet A. T. (44° 10' Lat., 71° YI\ Long.) as 

 representing the lowland near Mount Washington, and 

 was pleased to find that it checks quite well with Barrell's 

 2450-foot ^^Becket terrace" of the Cretaceous. A lot 

 of points rise only a short distance above this one (Mitten, 

 Pine Peak, and Mount Little Wildcat, Rockybranch 

 Ridge Stairs, Crawford, Parker, Black, Saunders). It 

 would not be hard to imagine lower levels, but the 

 independent coincidence of my judgment with Barrell 's 

 figure gives me some confidence. 



But how about the ''lawns" and shoulders of the 

 ''Alpine garden" which Goldthwait takes to be remnants 

 of an old grade? I should explain them thus. The 

 Cretaceous 4000-foot ridges were not above timber line, 

 but the elevations of the Tertiary carried them above 

 timber line, and the parts projecting were subject to more 

 rapid erosion. When they got high enough, and the 

 climate rigorous enough, glaciers occupied the ravines 

 and carved the cirques, while all during the times of 

 elevation the rivers were busy cutting down to lower 

 grades. I think cirques occur lower than Goldthwait is 

 inclined to allow, for North and South Baldface and 

 Eagle Crag seem to surround a well-marked cirque 

 extending from 3000 to 2000 feet. 



Finally, the advancing ice sheet swathed all the lower 

 parts of the mountains in ice, and put a stop to the local 

 carving, did some polishing, but little additional heavy 

 cutting. It seems to me that the ice surface must have 

 been for a long time at level; this "lawn," now between 

 4800 and 5500 feet, did not check the wasting by avalanche 

 of the nunataks above, but started to produce that ac- 



