136 SEFSTROM ON THE FURROWS WHICH TRAVERSE 
with a particularly barren mass of diluvial alpine gravel. At 
Eichstadt the alpine limestone appears in the solid rock above 
the loose Lias and Keuper formations. Even here the alpine 
limestone has also formed mountains similar to those of the Alps, 
with precipitous sides. The Spessart, which for the most part 
is composed of granite and gneiss, has in its external configura- 
tion such a similarity to those Scandinavian mountains which 
consist of the same hard materials as in Smaland, that it is par- 
ticularly striking to the eye. 
Cologne, 4th September. 
* * * * * * * * * * * 
Since my last communication on the subject of the boulder- 
stones, I have passed over the Taunus, where I remained some 
time at the baths in Langenschwalbach, and have since been in 
England. 
The Taunus, as is known, is composed principally of a mass of 
clay-slate, which is considerably elevated above the surrounding 
country. The upper surface is pretty even, but covered with 
small hillocks, which apparently were rounded by the boulder- 
flood. The higher peaks which remain, and which could not be 
worn away by the flood, are composed of harder substances— 
trap, schaalstein, harder kinds of clay-slate, and the like. The 
deep valleys, on the contrary, which are found in this tract, and 
which have very precipitous sides, do not seem to have been 
caused by the flood, but appear in most places to be of a more 
recent origin. 
A circumstance which had drawn my attention during my jour- 
ney from Munich was here explained. On this road, particularly 
around Niiremberg, there occur in the superficial detritus (dam- 
jord), which otherwise is composed of clay mixed with sand, 
large and small grains of a snow-white quartz of such a singular 
appearance that it could not be mistaken for any other sort of 
quartz. I was, therefore, very curious to discover where this 
quartz occurs in situ, particularly since, to my knowledge, it 
does not belong to the minerals which are found northward. 
Contrary to all expectation, however, it was found in the clay- 
slate formation of which the Taunus is composed, and which 
stretches easterly towards Cassel, as well as through the whole 
of the southern part of the Hartz. It is found there in veins, 
often of such considerable dimensions that they are worked to 
procure materials for road-making. When the slate was ground 
