=e 
358 The Glacial Theory of Prof. Agassiz. 
from Ecluse, near Geneva, to Aarau, a distance of 130 miles. (Sur 
tout le versant meridional de Jura, depuis le Fort de I’Ecluse jusqu’aux 
environs d’Aarau.) When the surface is newly exposed, it is smooth 
as a mirror, marked with furrows and fine scratches, and exhibits the 
roches moutonnées, or rounded undulations and domes, But the most 
characteristic fact is, that the furrows do not run from the summit down- 
ward, but in a horizontal or oblique direction, along the face of the 
ridge, showing that they were impressed by a body moving parallel to 
the chain along its southern flank. In form and position, they are, in 
short, precisely similar to the furrows produced by existing glaciers on 
the sides of the valleys along which they move... Further, these polish- 
ed and striated rocks are not confined to the declivities of Jura, but are 
found equally at their foot, in the bottom of on great tare mexalloys 
wherever the rock is calcareous,* 
In addition to these striated and. alishell cites rae has a mo- 
raines, and in these moraines patches of stratified deposits are found, 
‘such as are now formed in small lakes on the flanks of glaciers. It has 
thousands of erratic blocks, distinctly derived from the Alps ; and, that 
nothing might be wanting to complete the chain of evidence, Jura has 
its lapiaz, or water-worn gutters, where no water now runs; its creur, . 
or water-worn pits, in situations not dominated by any rock whence 
a cascade could fall; and its salient peaks, surrounded by coronets of 
boulders, as in Kees 7. Now, as no ridge occurs between the Alps 
and Jura, it is evident that the mass of ice which pressed against the 
southern declivities of the latter to the height of 3500 feet or more, 
with a force sufficient to cut and groove the surface longitudinally, 
must have extended far into the great valley or low country ; and as 
striated rocks and travelled boulders are also found all over the bottom 
of that valley, and on the Alps at its opposite side, we have before us 
a concatenated series of facts, leading almost inevitably to the cenclu- 
sion that a mer de glace, or vast sheet of ice, once enveloped the Alps 
and Mount Jura, and covered the whole of the low country between them. 
Hemmed in by the two mountain chains, the ice could expand only in a 
northeast or southwest direction, and Agassiz infers from the direction of 
the stria, that in the middle and northern part of the valley the motion 
was northeastwards, or towards the lake of Constance. 
Erratic Blocks of the Alps and Jura.—The large Alpine boulders 
found on Mount Jura » forty or fifty miles from their native rock, have 
been a stumbling block to geologists for the last half century. As the 
subject, though: tier discussed in books of science, may be new to 
sone neiiiiae egal we:shall: premize a shor! account of the vena 
Jandatan eens 
