336 Geological Society. 
inference that the Balaniand corallines which also cover the rocks, and 
which are of the same species as those found on the shells of the re- 
cent strata in contact with the rocks, prove that the gneiss was long 
submerged beneath the waters, and that the shells werenot washed up 
by an inroad of the sea upon the land. In theisland of Orust, opposite 
Uddevalla, I found similar appearances, and on other parts of the 
western coast ; but on the eastern shores of Sweden or those bor- 
dering the Baltic, both to the north and south of Stockholm, a 
marked distinction is recognised. In the assemblage of fossil shells 
which there occur in beds of upraised gravel, sand, and clay, the 
testacea belong to recent species, yet not to that assemblage which 
inhabits the ocean, but to a confined number of mixed freshwater 
and marine species characteristic of the brackish waters of the Baltic. 
Such deposits rise near Stockholm to the height of 200 feet above 
the sea, and show that the relative level of land and sea has greatly 
changed, not only since the existing testacea were in being, but also 
since the Baltic was divided off from the ocean as an inland sea 
freshened by a superabundance of river water. 
It is well known that these parts of Sweden are densely strewed 
over with huge erratic blocks, many of the largest of which oc- 
cur in the highest part of ridges of sand and gravel, finely stratified 
or made up of a continued series of thin layers of sand, loam, and 
gravel. In one of these ridges, at Upsala, I found layers of marl, 
containing perfect shells of recent species, such as live in the Baltic. 
The ridge was about 100 feet high, and on the summit of it were 
blocks of gneiss and granite, measuring from eight to ten feet in 
length. I saw similar boulders but inferior in size overlying some 
deposits of recent shells in Orust and near Uddevalla*. Hence it 
is evident that the transportation of these rocky fragments into 
their present position continued after the period when the modern 
shelly formations of both the coasts of Sweden were accumulated. 
In addition to the facts enumerated in my paper on Sweden in the 
Philosophical Transactions for 1835, in regard to the agency of ice- 
islands, I may mention a fact observed by Dr. Beck on the coast of 
Jutland. He has ascertained that on the breaking up of the fringe of 
ice which encircles the coast there during winter, small islands of ice 
float off and carry with them not only small gravel from the beach 
but stones four feet in diameter firmly frozen into the solid mass. 
These ice-floes are sometimes driven eastward into the Cattegat, and 
have been known to stop up the narrow part of the passage of the Great 
Belt, and to cause new reefs of rocks thus transported on which ves- 
sels, and a few years ago a Danish man-of-war, have been stranded. 
If such power can be exerted by ice-islands, only a few hun- 
dred feet in diameter, in latitudes corresponding to those of En- 
gland, we may be well prepared to find thatislands several leagues in 
circumference may remove blocks of the magnitude of small houses. 
Capt. Bayfield, in commenting on the inferences which I had 
drawn as to the transporting power of ice in the Baltic, communi- 
* Phil, Trans., 1835, p. 33. 
