in a polished state, but their composition was sufficiently evident. The
basis was usually felspar, or sometimes clay stone, and the crystals,
which superabounded in it, and from which it derived in a great measure
its beauty, were chiefly of felspar, but sometimes likewise of
quartz. In some specimens I observed hornblende crystals, which
gave the specimen the appearance of sienite.
Now the structure of this rock, which extends over a considerable tract
o f country, is said to be this. The lowest bed o f all is sandstone, containing
petrifactions. Over this lies a very thick bed o f porphyry:
over this a bed o f a kind o f coarse porphyry, to which the Swedes give
the name o f porphyry breccia. Lastly, the summit of the rock consists
of a thick bed of greenstone. I have given a representation o f the
structure of this curious rock in Plate XIII. figure 5. As I did not myself
examine this rock, I cannot authenticate the preceding account
from my own testimony. But from the high opinion I entertain of
the accuracy o f Mr. Hjelm, and the pains which he took to ascertain
the point, I have no doubt ot the correctness o f the account which I
have given. It shows the inaccuracy of the Wernerian classification of
rocks in two .particulars. First, in confining porphyry to the primitive
rocks, whereas there can be no doubt that it exists also in the transition
rocks. Indeed I have little doubt that it will be found even in floetz
rocks. Every mineralogist must have observed greenstone occasionally
putting on a porphyritic appearance. The other particular in which
the Wernerian classification o f rocks is corrected by the structure o f the
rocks in Elfdal, is, that gray wacke is not the only sandstone which occurs
among the transition rocks. For the sandstone at Elfdal has no resemblance
whatever to gray wacke. It is, I am told, a hard white sandstone,
consisting chiefly of grains of quartz.
The petrifactions which this sandstone contains demonstrate that it
cannot belong to the primitive rocks. I received a list of these petrifactions
from a friend in Sweden, but I dare not venture to insert
them here, because I am not absolutely sure whether they were found
in the sandstone immediately under the porphyry, or at some distance.
The absence o f fragments of clay-slate in this sandstone proves that it
does not belong to gray wacke. Perhaps it may be thought by some
that the whole suite o f rocks in this plan belong to the floetz class of
rocks, and not to the transition. This is certainly an opinion that may
be taken up. There is nothing to lead us to place these beds among
the transition rocks but the porphyry, which constitutes the most conspicuous
and important o f them. This surely of itself is not a sufficient
reason. It appears to me much more reasonable to be determined
by the sandstone which has hitherto been considered as characterising
the floetz rocks. I f we adopt this opinion, which appears to me by far
the most rational, it will follow that the rocks o f Elfdal only point
out one mistake in the Wernerian classification of rocks,—-the confining
porphyry to primitive rocks; whereas in fact it extends over all the
three formations o f primitive, transition, and floetz. W e must expect
to find various other modifications in the Wernerian classification besides
this, as we proceed in the difficult but important task of examining
the structure o f the surface of the earth with rigid accuracy, regardless
o f all preconceived opinions, and anxious only to discover the
truth.
Elfdal, famous for its porphyry quarries, lies a little to the east side
of the river Dal, a little to the north of the lake Siljar, through which
the river Dal runs. The quarry lies rather farther north than latitude
01°. Very large blocks of porphyry are raised from this quarry, and
afterwards hewn into the wished for shape, and then polished. In this
state it has a very great degree of beauty, while it is so hard as not to
be liable to be injured by the weather.. The pedestal of the statue of
Gustavus III. in Stockholm, and many other exquisitely beautiful ornaments
with which that capital is adorned, are constructed of this porphyry.
It is made likewise into candlesticks, vases, paint boxes, and
a variety o f other utensils; and these are exposed to sale in Stockholm,
and are under the care of Mr. Hjelm-, who sells them. Perhaps this
porphyry work may be styled, without impropriety, the most complete
manufactory in Sweden.
Not considering myself entitled, from the small portion ofDalecarlia
which I traversed, to give an account o f its geognostic structure, and