458 Goldthwait — Old Graded Upland on the 



Throughout the area just described the lawns are covered 

 with loose rocks and glacial bowlder clay. Although at first 

 glance one would probably say that this is post-glacial talus, 

 cracked off from the exposed ledges by winter frosts and 

 pushed slowly clown the slopes, the disposition of the frag- 

 ments, and particularly the lines of white quartz blocks which 

 may be seen trailing in the direction of motion of the con- 

 tinental ice-sheet, not straight down hill but obliquely down or 

 even up hill, from striated parent ledges, indicate rather that 

 this sheet of loose rock is not now on its way down hill, but 

 rests exactly where the ice sheet dropped it. In the steep- 

 walled ravines there has of course been considerable sliding of 

 this debris in post-glacial time ; but on the gentler slopes of 

 lawns and cones generally it seems to record little if any recent 

 movement. It is bowlder clay in the first stages of production, 

 which, for want of a specific name we may call " block till." 



While the lawns are thus virtually continuous along the line 

 of the northern peaks from Boott's Spur to Mount Adams, the 

 greater part of the crest of the range in this distance is occupied 

 by the cones themselves. A brief description of these may 

 now be given. 



The Cones. — Washington, the highest of the cones by nearly 

 500 feet, is also the roundest. While it is somewhat steeper 

 on the southeast side, the asymmetry is so slight that the moun- 

 tain appears in profile as a rounded dome from every side. As 

 already mentioned, however, the Great Gulf has been cut back 

 into the north side of the cone fully half way to its summit. 

 This extraordinary foreground, as well as the similar cirque 

 re-entrants of Huntington's and Tuckerman's Ravines on the 

 east side, lend variety to the appearance of the mountain as 

 seen at close range from different viewpoints. The surface of 

 the cone is covered even to its top with block till like that of 

 the lower slopes and lawns, with which are associated peculiar 

 streaks and patches of ordinary glacial bowlder clay. The 

 verdure of these patches, especially where they are well watered 

 by springs so as to support a luxuriant growth of Alpine 

 flowers, greatly relieves the cold gray landscape of the rocks. 

 Here and there exposures of bed rock appear, especially on the 

 southeast side of the mountain, where low cliffs may be seen ; 

 but these have in most places been so much cracked and 

 loosened that the distinction between them and the scattered 

 blocks is not easy to see. To some extent the ledges, particu- 

 larly at the summit, show the flatfish, smoothed crowns charac- 

 teristic of glaciation, but there are no distinct striae or grooves 

 there. The presence of both bowlder clay and erratic bowlders 

 on and around the summit proves, as Professor Hitchcock dis- 

 covered in 1875, that the cone was completely covered for a 



