The Glacial Theory. 



139 



clincd or steeper than the interior, 'idly, Lateral moraines, nearly of 

 the same composition as the former, but arranged in longitudinal 

 mounds, deposited on the two flanks of the valley at the same height 

 two by two, following all the contours of the windings, entering 

 every sinuosity, and having an inclination which represents that of 

 the surface of the glacier, odly. Median moraines, resulting from the 

 junction of the lateral moraines of two glaciers uniting. These mo- 

 raines present the form of a triangular prism, whose axis is in the 

 direction of the valley, and the nearer its middle, the nearer the size 

 of the glaciers approaches to equality. 4:thly, Whenever the nature 

 of the rocks permits, the bottom and sides of the valley exhibit per- 

 fectly polished surfaces, together with particular indentations, in the 

 direction of the glacier's motion ; also strice, or fine parallel lines, 

 likewise runnhig in the same direction, that is to say, in the direc» 

 tion of the valley's inclination, but never following the greatest in- 

 clination of its sides. These striae are particularly characteristic. 

 Lastly, Large blocks not rolled, often resting, as in equilibrio, on one 

 of their smallest faces, and forming lines, etc. more or less extensive, 

 on the sides and bottom of the valleys. 



After describing numerous instances of moraines in the 

 valley of St. Amarin, M. Renoir remarks. 



One of the reasons which led me to consider these accumulations 

 of stones as moraines, is, that their absolute height is greater in the 

 middle than towards the rocks which encompass the valley, as is the 

 case with all the moraines of existing glaciers. The cause of this 

 peculiar form is known, and has been stated by the savans who have 

 occupied themselves with glaciers ; a form peculiar to moraines, and 

 which is the very opposite to that which deposits formed by rapid 

 currents would assume. Moreover, polished rocks appear along the 

 whole right bank of the rivulet Thur, at heights more or less consi- 

 derable, whenever the rocks have been sufficiently hard to preserve 

 their polish, or when they have been somewhat protected by their 

 position from the action of atmospheric agents. It is true that this 

 polish is no longer perfect, and has, consequently, been incapable of 

 preserving the striee ; but we have noticed, that the same deteriora- 

 tion is observable not far from glaciers, when the rocks are not 

 very hard, or when they have for a long time been left by the gla= 



