196 
GEOLOGY OF THE FIRST DISTRICT. 
thus those of the valley of the Rhine are similar to the rocks of the Grisons; those of the 
valley of the lake of Zurich, and of Limmat, are fragments of the rocks of the mountains 
of Claris ; those of the basins of the Aar and of Jura, came from the high mountains of the 
Canton of Berne. The blocks were observed to be most abundant upon the hills and declivi¬ 
ties which are opposite the embouchure of the principal valley ; and in the Jura, it is in situa¬ 
tions opposite the embouchure of these valleys that the blocks are found at the greatest 
elevation, some being nearly four thousand feet above the sea. Between the points whence 
these started, and their present position, the broad deep valley of the Aar, and the lower 
crests of the Jura mountains intervene, and if seems that they must have passed this space.* 
The sandy plains of Holstein, Westphalia, Hanover, Mecklenburg ; the shores and plains 
of Pomerania, Prussia and a part of Poland ; and all the sandy plains bordering on the Baltic 
sea and German ocean, from Ems and the Weser to the Dwina, Neva, and even to St. Peters- 
burgh, are strewed with boulders and erratic blocks. They are not scattered irregularly, but 
are in groups covering thickly certain spaces which have an oval form, and of which the axis 
has a direction nearly north and south. They are sometimes very large, and partly or entirely 
covered by the sand. They consist of sienite, granite and other crystalline rocks, and com¬ 
pact limestone containing orthoceratites and trilobites, which characterize it, not only as 
transition limestone, but also as belonging to certain beds of this rock in Sweden and Norway. 
The other rocks indicate the same general direction of transportation, having a perfect simi¬ 
larity in mineral composition and imbedded minerals, to masses of the same kinds of rocks 
in those countries, and which have not been observed elsewhere in that part of the world. 
Housman, after a careful examination of the facts, has arrived at the conclusion, that these 
blocks are separated from their parent beds by the Baltic sea, as those of the Jura are by the 
valley of the Aar.t 
Crossing from Holstein to Sweden through Scania, the train of these blocks is not lost 
sight of for an instant. The soil is covered in many places in the Swedish provinces by the 
masses of the wrecks of mountains, as they are called by most travellers, who have been 
struck by their appearance. In Smoland, Scania, Sudermanie, and Uplande, the blocks are 
accumulated in masses forming small hills of a peculiar form, long and narrow, more elevated 
at one extremity than the other, ranging from north-northeast to south-southwest, and composed 
of sand and granitic gravel, containing enormous blocks of granite and sienite. These rocks 
continually increase in numbers from the countries south of the Baltic, to those on the 
north towards their parent sources ; but they do not appear to be larger than those at a great 
distance.! 
Russia and Finland present immense accumulations of erratic blocks. In Finland they are 
so numerous and large, that the roads are made crooked to avoid them. 
In England they are common, and in the counties of Norfolk, Suffolk, Cheshire, the east 
Beongniart, Terrains de I’ecbrce du globe. Paris, 1829, p. 76. 
t Id. pp. 77, 80. 
