i87 7.] The Loess of the Rhine and the Danube . 81 
channels would probably be cut out with precipitous sides, 
and it was not until these sides had been sloped down by 
the action of rain that the loess was deposited. 
Adding to the arguments already urged the fadt that no- 
where in the loess have any river shells been found, whilst 
they abound in the beds of all our large rivers, we have a 
case so strong against the theory, that, until its upholders 
offer some explanation of the fadts arrayed against them, 
we may fairly refuse to receive it. And if we are forced to 
conclude that the loess has not been deposited by the rivers, 
and that the excavation of the valleys took place at an 
earlier time, we must believe that in some way or other 
these valleys were again filled with water up to the height 
to which the loess reaches. This is the conclusion of the 
Austrian geologists with regard to the valley of the Danube, 
and that of Sir Charles Lyell with regard to that of the 
Rhine also ; and the next question we have to consider is 
whether the waters were pounded up through oscillations of 
the surface of the land, or in some other way. 
The valleys of the Danube and the Rhine were in ex- 
istence in early tertiary times, and we find two great accu- 
mulations of fossiliferous strata in them, —one miocene, the 
other post-tertiary. Both appear to be due, not to deposits 
from rivers wearing down their channels, but to interruptions 
to their drainage so that their channels were raised. The 
first of these interruptions is known to be due to the great 
volcanic disturbances during which the Alps were partly ele- 
vated ; the second I hope to show was caused by the ice of the 
Glacial period blocking up the drainage of the continent. 
I have already alluded to the transported boulders in the 
loess, and to its fauna, indicating its glacial age. Along the 
northern flanks of the Carpathians, the Scandinavian drift 
rises to heights of from 1000 to 1200 feet ; considerably 
higher than the low passes that lead into the basin of the 
Danube. General Helmerson has done me the honour to 
inform me that the transported northern blocks in Russia 
also range up to heights of from 1000 to 1200 feet above the 
sea. As the Russian diluvial clay can be traced continuously 
up to and around the Carpathians into the basin of the 
Danube, we may reasonably conclude that the water over 
which the northern drift was floated was the same as that 
in which the loess was deposited. 
But it will be urged that “ the northern drift is a marine 
deposit.” It is so stated in most works on geology ; but 
excepting around the southern border of the Baltic, and just 
so far as, and no farther than, the Scandinavian glaciers 
VOL, VII. (N.S.) Cl 
