42 
THE GEOLOGIST. 
which are found adhering to the striated rocks in the neigh- 
bourhood of Christiana. 
3. On the diluvial deposits of the Black Forest, by Prof . From- 
HERZ. — According to the opinions of the author of this essay, 
all the diluvial deposits of the Black Forest originate from that 
locality, which, he says, may be easily proved by comparing 
these deposits with the strata composing that chain of moun- 
tains. They are, in fact, the effects of large currents of water, 
which originated in the chain itself, lliese currents arose from 
the overflow of the great lakes which occupied the elevated val- 
lies before and during the diluvial period, and which took place 
during that epoch, not only over the whole extent of the Black 
Forest, but the neighbouring country also, by dislocations and 
disruptions in the existing strata. The channels by which the 
waters of these lakes entered the plains, and which are now in- 
dicated by ravines and vallies, with more or less escarpments, 
all bear the impress of a recent formation. 
The diluvial deposits of the district differ entirely from those 
of glacial origin; as moraines and striated rocks are altoge- 
ther absent ; those which are rounded in any way bearing evi- 
dence of other than glacial action. 
4. Observations made on the glacier of the Aar, in company with 
Messrs. Agassiz and Desor, by Dr. Vogt. — The snow ahvays 
falls in these elevated regions in the form of crystals, and not 
granular ; frost occurs there as well as in the plains. The water 
which is derived from the melting of the snow exposed to heat, 
everywhere infiltrates the mass, and cements the separate crys- 
talline particles ; the transformation is more and more complete 
in proportion to the depth of the glacial mass. Every glacier 
presents a series of respective strata of snow, frozen snow, and 
snow-ice ; these are nearly horizontal, and about 4|^ feet thick, 
appearing to be the accumulations of several successive years. 
The siu'face of the beds is distinguished by the fragments and 
dust upon it. Colouring matter infiltrates equally through 
