70 The Loess of the Rhine and the Danube. [January, 
clay with which they are covered may have been washed 
down from the hills above them. 
The loess may be traced all round the flanks of the hills 
that surround the great plain between Basel and Bingen, 
and also on the hills that in some places rise up like islands 
in its midst. Thus Sir Charles Lyell notes that it covers, 
up to a height of 1600 feet above the sea, the Kaiserstuhl, 
— a volcanic hill which stands in the middle of the great 
valley of the Rhine, near Freiberg, in the Brisgau. It is 
also spread over the volcanic hills of the Lower Eifel. Dr. 
Samuel Hibbert, in his “ History of the Extindt Volcanoes 
of the Basin of Neuwied on the Lower Rhine,” published in 
1832, gave many instances of the intercalation of the loess 
with beds of volcanic ashes near Andernach. Much white 
pumice is spread over the loess, and it seems to be well 
ascertained that both during its deposit and afterwards the 
volcanoes were adtive. The veteran geologist, Herr Henry 
von Dechen, has mapped out these deposits, and described 
them in his “ Geognostischer Fichrer zu dem Laacher.” 
He has informed me that one of the highest patches of the 
loess on the volcanic hills lies south of Andernach, near the 
hill of Korrets, at an altitude of about 620 feet. Dr. Hibbert 
appears to have found it higher, for he states that on the 
Mahlsberg the loess attains an elevation of 800 feet above 
the sea, or 600 feet above the river, and is sometimes 60 feet 
thick. With regard to the pumice that is abundantly spread 
out on the top of the loess between Andernach and Coblentz, 
and which Herr von Dechen informed me indicated that 
the volcanoes were adtive at the time of the close of the de- 
position of the loess, it may be worth remarking that the 
Challenger explorations have shown that great quantities of 
pumice are spread over the bed of the ocean, proving it to 
be a common produdt of submarine volcanoes ; so that it is 
quite in accordance with our knowledge of its production to 
suppose that the volcanoes of the Eifel at the time of its 
eruption may have been submerged beneath the waters from 
which the loess was deposited. 
The loess extends up the valleys of the tributaries of the 
Rhine. The basin of the Neckar is, according to Sir Charles 
Lyell, filled with it. It is of great thickness, and at Can- 
stadt, near Stuttgart, overlies a bed of gravel, and contains 
bones of the mammoth and the woolly rhinoceros. There 
are thick deposits of loess in the valley of the Main. I had 
the great advantage of examining it near Wurzberg, in the 
company of the celebrated geologist Dr. Sandberger. It 
has been principally preserved, from the effedts of great 
