130 SEFSTROM ON THE FURROWS WHICH TRAVERSE 
away whole tracts of transition strata in West Géthland. But 
when we come nearer, we perceive, partly that the sandstone of 
these rocks is of a much harder nature, and more especially that 
the steep precipices have not been affected by the petridelaunian 
flood, but that, on the contrary, they are formed of clean un- 
changed surfaces, produced by the falling down of the large 
masses of stone which now lie around the foot of the remaining 
rocks, similar to those at Hunneberg and Halleberg in Sweden. 
Had I not previously had the opportunity of acquiring a correct 
knowledge of these last-named rocks, it would have indeed been 
difficult to comprehend the true cause, although it now appears 
to me very probable, and even discernible in the above-men- 
tioned prints. 
The undermost layers of sandstone, being looser, have evi- 
dently been undermined; and, in consequence, the uppermost, 
overhanging like the trap in West Gothland, have since fallen 
down. The existence of the steep sandstone precipices is not how- 
ever everywhere to be attributed to this cause; but many appear 
to have originated in the rending of the sandstone masses, 
when the basalt, which is now to be found on the higher moun- 
tains in the neighbourhood, was forced up. That such is the case 
may be seen by attentively tracing the layers of sandstone along 
the banks of the Elbe, where we find that the layers between the 
great crevices incline here and there; and probably these deep 
crevices, which are found in the masses of sandstone after the 
protrusion of the basalt, have in some degree assisted to make 
the undermost loose layers of sandstone accessible to the boulder- 
flood, particularly in those places where the crevices lie in the 
direction of the flood, and are open at both ends. The nature 
of the locality seems to favour this opinion; for in the cross 
valleys, and those closed at the upper end, the working of the 
flood is evidently less. Besides, the looser sandstone has also 
resisted the force of the flood, viz. where it is closely intersected 
with veins of basalt, in the way in which it occurs at der kleine 
und grosse Backofen, and which have sheltered Schramsteine, 
which lies to the southward. On the lower part of the preci- 
pices in that neighbourhood, traces of the course of this flood 
are seen, whilst the upper part of the precipices have clean sur- 
faces. The tops, on the contrary, are always rounded. I have 
therefore no doubt but that the boulder-flood even here has 
acted in the same way as in Sweden. 
ts 
