116 SEFSTROM ON THE FURROWS WHICH TRAVERSE 
river, that it cannot be supposed to have originated from the 
latter. The furrows found in the neighbourhood also show 
that the origin of the giant-caldron must be ascribed to the 
boulder-flood. 
That such a giant-caldron could not be formed in a short time 
is evident, as this cannot have been the effect of force; the hol- 
lowing must have been produced by a long-continued friction. 
The second question, namely, whether the stream had pro- 
ceeded uninterruptedly or occurred periodically, is still more 
difficult to answer. The requisite data could not be quickly 
collected, for they are to be derived principally from excavations 
of the earth, or from sections made by the action of water ; 
and as such works are not undertaken expressly in behalf of 
geology, we must wait until the circumstances present them- 
selves for making observations. These ought not to be neglected, 
for after a short time the loose earth falls together, and its 
vertical section is no longer visible; and we ought to be the 
more anxious that such observations should be made, as the 
explanations derived from them may be of importance in an 
agronomical relation. 
From the little which hitherto has been observed, there is 
reason for believing that this flood was not continuous. The 
alternations in our strata appear to show this. I have seen, 
for example, in a pit from whence the gravel for repairing the 
roads has been taken north of Krigsberg church in East Goth- 
land, common granite sand alternating with another sort, which 
was probably sandstone sand, at all events not granite sand ; 
and it is difficult to understand how this could be the case 
without some interruption in the flow of the stream. 
This question will probably at some future time be treated 
just as circumstantially as there is now little to say on the sub- 
ject. 
58. 
Was the Boulder-flood of great violence ? 
Had the questions in the two preceding sections been an- 
swered, this would also have been solved; but in default of this 
some phenomena must here be mentioned, which in the mean 
time may serve to prepare the way for a solution of it. 
a. It has already been mentioned, that there are to be ob- 
served at Blekinge large rocks which have been removed up- 
