Ch. XVI.] 



GLACIEE LAKE— THE MARJELEN SEE. 



077 



61 i 



its periodical drainages, and the basin had not yet been filled 

 again. Such a state of things gave me an opportunity of exa- 

 mining a point of great geological interest, namely, the form 

 and structure of a large terrace or line of beach which encircles 



Fig. 23 



Mctrjelen See 



e 



Section of the glacier lake called the Marjelen See. 



a b c. Terrace of cletrital matter formed on the margin of the lake when full 



d. Surface of lake 40 feet below its usual level. 



e. Mass of floating ice with included stones detached from the dam. 

 /. Boundary hill composed of mica-schist. 



the lake basm all round its margin, and which constitutes 

 its shore when it is full, and when its surplus waters flow 

 over to the Yiesch valley. I satisfied myself that this terrace 

 is a counterpart of one of those ancient shelves or parallel 

 roads, as they are called, of Glen Roy in Scotland, which, as 

 Agassiz first suggested, were probably formed on the edge 



dammed up by ice, which may 



Mar 



jelen See consists chiefly of sand and small pebbles of quartz, 

 with stones of mica-schist, gneiss, granite, and a hornblende 

 rock, most of them angular and from a few inches to four 

 feet in diameter. The sand was stratified, but I could find no 

 organic remains in it. The width of the shelf, a &, (see fig. 23) 

 is about sixteen paces, and its slope varies from angles of 

 5° to 15°. The slope from b to c, which is under water when 



