72 M. Cli. Martins on the 



village of Ouches, the last in the valley of Chamonix. It is 

 there that the glacier has left the most varied and evident 

 indications of its passage. The enormous pressure that must 

 have been exerted to force tlie entrance of the narrow gorge 

 of Montees, the change in the direction of the valley, all con- 

 tribute to produce those phenomena which we observe at the 

 foot of promontories, or near contractions which narrowed 

 the bed of existing glaciers. 



In front of the village of Ouches, on the right bank of the 

 Arve, three hillocks are to be seen of a characteristic form ; 

 they are rounded in front, and precipitous behind. We at 

 once perceive, that the force which has worn away the in- 

 clined strata of argillaceous steaschist which composes them, 

 came from the upper part of tlie valley, and spared the face 

 turned towards the lower part of it. Hence this rounded 

 form in front, terminating abruptly in an escarpment turned 

 in the opposite direction. Let us examine these hills nearer 

 at hand ; everywhere, on the summit and sides, we find rec- 

 tilinear grooves, — those fine striae running in the direction of 

 the valley, and which could be traced only by glaciers ; and, 

 to complete the demonstration, numerous blocks of protogine, 

 often enormous, with sharp angles and trenchant ridges, rest- 

 ing on polished and striated surfaces. Even to the height of 

 5y3 metres, the whole mountain of Coupeau, above the right 

 bank of the Arve, is covered with moutonned rocks, which 

 disappear, so to speak, under innumerable erratic blocks. 

 The strise which furrow these rocks are not horizontal ; they 

 could not be so, for this mountain forms a salient promon- 

 tory in the valley, and the glacier having raised itself up 

 against the obstacle which opposed its progress, has grooved 

 the ascending stride which run from the front backwards, like 

 those we have mentioned on the glacier of the Aar, at the 

 foot of the promontory which bears M. Agassiz's pavilion. 



Thus the most convincing traces which a glacier can leave 

 of its passage at the entrance into a defile, hills rounded in 

 front and precipitous behind, moutonned rocks with grooves 

 and rectilinear strise, horizontal in the bottom of the valley, 

 ascending on the promontory which contracted it, and a la- 

 teral moraine, composed of angular blocks suspended on the 



