1862.] EAMSAY GLACIAL OKIGIN OF LAKES. 187. 



above the water. Outside the moraine lies a flat marsh, still 

 retaining traces of having been a lake, once also dammed by a second 

 and outer moraine, formed chiefly of large angular blocks of gneiss, 

 piled irregularly on each other like the old moraine of Cwm Boch- 

 Iwyd, above Llyn Ogwen in Caernarvonshire. Quantities of moraine - 

 matter strew the valley for two or three miles further down to the 

 little marshy lake at Waldbauer, which is also dammed up by 

 moraine-rubbish, in one place rudely stratified, like some of the old 

 moraine-heaps on the Jura and parts of the great moraine of Ivrea ; 

 or like the heaps of glacier-(i66mthat often border the lakes marshes, 

 and flat peat-mosses, once lakes, that diversify the lowlands of 

 Switzerland. At the upper end of the Alb Thai also, at the entrance 

 of Menzenschwanden Alb, I saw four moraines curving across the 

 valley, arranged concentrically one within another, hke those at 

 the end of the glacier of the Ehone ; and for many miles in the 

 Alb Yalley, both above and below St. Blasien, roches moutonnees 

 stand like islands through the alluvium, while it is also plain that 

 the sides of the mountains above have been to a great height smoothed 

 by ice. Nowhere however down to AUbruck, where the river joins 

 the Ehine*, did I see any " drift ;" and this village lying close on the 

 north side of the Jura, it seemed impossible that the higher ground 

 on the south side of that range, between the Lakes of Constance and 

 Geneva, should have been submerged during any part of the Glacial 

 period, while the country on the Ehine above Basel remained above 

 the sea. I therefore saw that the theory that the Pierre a hot and 

 its companion blocks had been floated from the Alps by marine ice- 

 bergs was untenable ; and a later examination of a portion of the Jura, 

 partly under the able guidance of Professor Desor, fully convinced me 

 that the ice that descended the great valley of the Ehone had covered 

 much of the low country and abutted on the south-eastern flank of 

 the Jura. 



Old Distribution of the Great Alpine Glaciers. — At that period, then, 

 of extreme cold, when the glaciers of the Alps flowed right across the 

 Miocene basin of Switzerland, a glacier of vast thickness (No. 1 on 

 the Map, PL YIII.), running from end to end of the upper valley of the 

 Ehone, debouched upon the lowlands at what is now the eastern end 

 of the Lake of Geneva, and spreading in a great fan- shaped mass 

 extended to the south-west several miles down the Ehone below its 

 present outflow from the lake, and north-east to the banks of the Aar, 

 about half-way between Solothurn and Aarau. The length of this 

 fan- shaped end of the glacier, from north-east to south-west, was 

 about 130 miles, and its extreme breadth about 25 miles. Another 

 great glacier (No. 5) descended in a direction opposite to the higher 

 part of the Ehone glacier, through the upper valleys of the Ehine, 

 and debouched upon a wide area that extends from Kaiserstuhl on 

 the Ehine, far to the north-east. In the centre of this area lies the 

 Lake of Constance. Between these, which were the largest glaciers 

 on the north watershed of the Swiss Alps, several smaller, but stiU 

 enormous, glaciers flowed in a north-westerly direction from the 

 * Between Basel and the confluence of the Aar and the Rhine. 



