opulation and the abundance of
forest. Carboniferous rocks abut against the flanks of the Ural
Mountains, along the sides of which they extend for a length of about a
thousand miles, with inter-stratifications of coal. Their actual contents
have not yet been gauged, but there is every reason to believe that those
coal-beds which have been seen are but samples of many others which will,
when properly worked, satisfy the needs of a much larger population than
the country now possesses.

Like the lower coals of Scotland, the Russian coals are found in the
carboniferous limestone. This may also be said of the coal-fields in the
governments of Tula and Kaluga, and of those important coal-bearing
strata near the river Donetz, stretching to the northern corner of the
Sea of Azov. In the last-named, the seams are spread over an area of
11,000 square miles, in which there are forty-four workable seams
containing 114 feet of coal. The thickest of known Russian coals occur at
Lithwinsk, where three seams are worked, each measuring 30 feet to 40
feet thick.

An extension of the Upper Silesian coal-field appears in Russian Poland.
This is of upper Carboniferous age, and contains an aggregate of 60 feet
of coal.

At Ostrau, in Upper Silesia (Austria), there is a remarkable coal-field.
Of its 370 seams there are no less than 117 workable ones, and these
contain 350 feet of coal. The coals here are very full of gas, which even
percolates to the cellars of houses in the town. A bore hole which was
sunk in 1852 to a depth of 150 feet, gave off a stream of gas, which
ignited, and burnt for many years with a flame some feet long.

The Zwickau coal-field in Saxony is one of the most important in Europe.
It contains a remarkable seam of coal, known as Russokohle or soot-coal,
running at times 25 feet thick. It was separated by Geinitz and others
into four zones, according to their vegetable contents, viz.:--

1. Zone of Ferns.

2. Zone of Annularia and Calamites.

3. Zone of Sigillaria.

4. Zone of Sagenaria (in Silesia), equivalent to the culm-measures of
Devonshire.

Coals belonging to other than true Carboniferous age are found in Europe
at Steyerdorf on the Danube, where there are a few seams of good coal in
strata of Liassic age, and in Hungary and Styria, where there are
tertiary coals which approach closely to those of true Carboniferous age
in composition and quality.

In Spain there are a few small scattered basins.