698 MEMOIR OF GUYOT. 



The facts and conclusions were communicated to the Geological So- 

 ciety of France at a meeting at Porrentruy, in September, 1838. The 

 communication is mentioned in the bulletin of the society for that year,* 

 but no report of it is given because the manuscript remained in his 

 hands unfinished, in consequence of his protracted illness the winter 

 following. The i)ortion then finished (which was withheld from publi- 

 cation because, by special arrangement between them, Agassiz in 1840 

 entered upon the special study of the glaciers, and Guyot on that of 

 the Swiss erratic phenomena, for their separate parts of a general sur- 

 vey) has recently been printed in volume xiii (1883) of the Bulletin of 

 the Neuchatel Society of Natural Sciences. In 1842 this manuscript was 

 deposited, by motion of Agassiz, in the archives of the Neuchatel So- 

 ciety, and in 1848 it was withdrawn by Guyot when he left for America. 

 It is to be regretted that publication was not substituted in 1842 for 

 burial. Its recent publication was made by the request of Guyot, early 

 in 1883, from a certified cop}" of the original manuscript. 



This paper gives the facts on which Guyot based his conclusions, 

 and since these conclusions comprise some of the most important of 

 the views now accepted relating to glacial motion and structure, and 

 antedate the observations of Agassiz, Eendu, and Forbes, they have 

 special interest. 



The fact of a less rapid movement of the bottom ice than the top, oiving 

 to friction, he ascertained by the observation that in glaciers of steep 

 descent, like the Khone at its rapids, and the Gries, the transverse 

 crevasses and the masses they cut oft" are at first vertical or nearly 

 so ; but below the rapids, where the slope is gentle and the crevas- 

 ses become mostly closed, the masses are inclined with the pitch up 

 stream, and this up-stream inclination is reduced at the termination 

 of the glacier to a few degrees. The crevasses, although closing 

 up below, are still traceable. He says the so-called layers are not 

 strictly layers ; but great numbers of cracks remain, which give to the 

 mass the appearance of being made up of beds several yards thick, 

 as may be seen in the glaciers of the Griudeiwald valley, Aar, and 

 others. 



Further: To this pitch in the stratification at the lower extremity, 

 the beds rising outward, Guyot attributes also the origin of the ma- 

 jestic ice chambers, whence in most cases flow great streams, as that 

 of the Khone, of the Arveyron at the foot of the Mer de Glace, of the 

 Liitschinen from the glaciers of Grindelwald. 



The more rapid movement of the center than the sides also was learned 

 from the Rhone glacier and others of steep descent. The crevasses, 

 at first transverse, were found to be arched in front below the rapids, 

 and increasingly arched to the extremity, and the successive crevasse- 

 lines were very nearly concentric with the semicircular outline of 



•Vol, IX, p. 407. 



