1 877. J The Loess of the Rhine and the Danube. 69 
character wherever it is seen. Land shells are scattered 
throughout it, and I found them up to a height of about 
mo feet above the sea, which was as high as there were 
good sections of it exposed ; but above this I traced it to 
the top of the hill, or to a height of about 1470 feet above 
the sea and 660 feet above the river. I took my altitudes 
by means of an aneroid barometer, calculating from the 
known height of the river at the bridge at Basel (803 feet), 
and though not absolutely correct they may be relied on to 
within a few feet, as I returned to my starting-point and 
found that only a small change had occurred in the baro- 
metric pressure in the meantime. Besides the land shells, 
small angular pieces of the local limestones and calcareous 
concretions are distributed throughout the loess. At the 
base of the hill it rests on a bed of gravel that has been 
cemented into a conglomerate by calcareous infiltrations. 
This gravel is composed of pebbles of crystalline rocks, 
rounded and subangular, and ranging in size from 1 inch up 
to 4 inches in diameter. With these are mixed angular and 
subangular fragments of the local limestones, of greater 
size. The highest point at which I noticed this old gravel- 
bed was 960 feet above the sea. It rests against the old 
valley bank, and the loess is distinctly superimposed upon 
it, and contains in its lowest part many pebbles derived 
from it. The importance of this fact will be recognised 
when I come to the discussion of the question of the origin 
of the loess. 
Between the base of the hill and the river there are three 
terraces of gravel capped with clay, at the heights respect- 
ively of 923, 860, and 830 feet above the sea, the lowest 
being about 25 feet above the river. I think that these may 
have been of more recent origin than the loess, and that the 
