120 MINERAL GEOGRAPHY. 
tains extending nearly round the island, inclose a central district 
of secondary formations. More than one-seventh of its surface 
is covered by bogs of turf, or peat, from 5, to 30 feet in thick- 
ness. As the coal of Ireland is neither abundant nor good, peat 
is generally employed by the inhabitants for fuel. Most of the 
bogs are in the midland counties. In the northern part of the 
island, is a body of basalt, covering an area of 800 square miles, one 
of the beds of which having formed in cooling an assemblage of 
regular fissures, constitutes what is called the Giant's Causeway. 
The pieces of silicified wood that are found in, and about, Lough 
Neah, have given origin to the fable that the hones in common 
use, are manufactured, by cutting pieces of hickory, so as to be 
composed partly of sap, and partly of heart wood, and immersing 
them in its waters. Gold has been found in Ireland, also small 
quantities of lead, and zinc, and a larger amount of copper ; — the 
latter especially at Allahies in the county of Cork, but the mine- 
ral wealth of this island is not very considerable. 
Scotland. Nearly the whole of the northern part of this 
kingdom, comprehending the Highlands, and the isles, is occu- 
pied by the most ancient primitive rocks; granite, gneiss, and 
mica slate, which at some points are covered by formations of 
sandstone, and at others give place to more recent rocks, of ig- 
neous origin. In its southern part, are transition strata, and be- 
tween the two, are extensive coal formations, extending across 
the island, on both sides of the Clyde and Forth, and the princi- 
pal seat of the manufacturing industry of Scotland. The coal is 
accompanied as in England, by clay iron stone, giving rise to im- 
portant establishments for the manufacture of iron. The lead 
mines of Lanarkshire, are inconsiderable in comparison with 
those of England, Spain, and the United States. 
England. The more recent strata in the middle and south- 
eastern counties, from the old red sandstone upwards, have been 
sufficiently noticed and described. The older rocks are in the 
west, and the oldest primitive are rare. In the granite and schist 
of Devonshire, and Cornwall, but especially in the latter county, 
are very productive mines of tin, and copper. The lead mines 
are mostly in the northern counties, Northumberland, Cumber- 
land, and Durham ; also in Derbyshire and Flintshire, in the 
oldest secondary limestone and the associated beds, which also 
yield considerable quantities of zinc, and manganese. Iron, copper, 
tin, lead, zinc, and manganese, are the metals furnished to com- 
merce by the mines of England. 
France. There is a large body of primitive rocks in the 
North-western corner of France, in ancient Brittanny, and on the 
lower waters of the Loire ; a second in the Pyrenees ; a third in 
the centre of the kingdom, amongst the head waters of the Loire 
and the Garonne — the seat in ancient times of volcanic action ; 
a fourth along the western declivities of the Alps — and a fifth, 
which is of small extent, in the Vosges, near Strasburg and the 
