460 Goldthwait — Old Graded Upland on the 



where the ice crowded through the saddles. In the case of the 

 Adams-Madison col, at least, the passage of the ice appears to 

 have scoured the crest of the range into a characteristic 

 hyperbola. 



The Ravines. — It has been stated that the cones and lawns 

 terminate sharply at the brink of steep walled ravines. This 

 feature is to be seen in the photographs (figs. 3 and 4) and the 

 map (fig. 2). Since an understanding of the ravines is neces- 

 sary to a proper conception of the upland, attention may now 

 be turned to them. 



Until recently the White Mountain "ravines" have been 

 generally regarded as the products of torrent sculpture, aided 

 by frost and landslides.* It is plain, however, to one familiar 

 with the origin of mountain forms that these great bowl-shaped 

 depressions or "mountain colosseums," as Starr King graphi- 

 cally called them, are glacial cirques. That they are extraordi- 

 nary, to say the least, was appreciated by those who early gave 

 them the names of " gulfs," " basins " and " ravines." Their 

 glacial origin, however, seems to have been overlooked. f 

 Around the five northern peaks there are no less than eight of 

 these cirques. They lie on all sides of the range except pos- 

 sibly the southwest, and trend in nearly every direction. In 

 size they range from the Great Gulf, whose crescentic head- 

 wall is 1500 feet high and whose length, measured along the 

 axis of the trough, is about three miles to the little bowl-shaped 

 Bumpus Basin, with hardly one-third these dimensions. Some 

 of the cirques like King's Ravine are isolated ; others, like Jef- 

 ferson Ravine and the Great Gulf, unite as tributaries to form 

 a single great trough. In all the headwalls are precipitous 

 and the rims well-defined. 



In view of this sharpness of form of the cirques, one is sur- 

 prised to find that local moraines at the mouths are wholly 

 absent. Even the debris near the headwalls, far back within 

 the ravines, is not so disposed as to demonstrate by any means 

 the recent occupancy of the cirques by valley glaciers. In fact, 

 the presence in King's Ravine of bowlder clay carried south- 

 eastward by the ice sheet far up into the cirque, and now lying 

 undisturbed on its floor, where local morainic ridges ought to 

 appear had local glaciers become re-established in the cirques 

 at the close of the ice age, seems to require that the carving of 

 the cirques took place before and not after the last epoch of 

 regional glaciation. If any local glaciers whatever survived 

 the ice sheet in the White Mountain ravines they must have 



* C. H. Hitchcock, op. cit., vol. i, p. 623. 



f Professor D. W. Johnson tells me that for several years he has cited the 

 White Mountain ravines as examples of cirques to students in his class, bas- 

 ing this opinion upon the contour maps of the U. S. Geological Survey. 



