good and reasonably dependable skiing and are being
developed into holiday resorts.

Soils

Fine, dark chernozem (black earth) soils, rich in loess and humus, occur
over a considerable portion of the northern Danubian plateau. They are
fertile, easy to work, and compare with the best soils in Europe. Away
from the river, approaching the mountains, there is a broader area that
is basically similar, but the subsoils are more porous and have allowed
the humus and loess to leach downward from the surface. The resulting
gray soil no longer rates among the finest, but it yields good crops in
some areas and, where it is less satisfactory, the land is forested.

The Thracian Plain has comparatively little of the finest soils, but it
has much soil that is more than adequate to produce reasonably good
crops. The best on the plain is locally called _smolnitsa_. It is
basically a chernozem, but it is less fully matured and coarser than the
darker variety along the Danube. The plain also features fairly
extensive areas of good brown and brown forest soils. Meadow soils occur
in large areas in the vicinity of Plovdiv. Some are irrigated and
cultivated.

Meadow and layered podzol (gray forest) soils occur in most of the
higher elevations throughout the country. Intermediate elevations
usually have brown forest soils, some of which are excellent. The
Maritsa and Tundzha and the major rivers that flow into the Danube have
wide valleys with alluvial soils. They may be coarse, but most of them
are fertile, drain well, and are extensively cultivated.

Vegetation

Both the natural vegetation and the cultivated crops that have replaced
it on all areas that could be put to agricultural use reflect the
transitional climate of the country. North of the Stara Planina the
original flora was a continuation of that on the Russian steppe. The
steppe influence was greatest in the east, giving way to deciduous
forests farther to the west.

Lands south of the mountains, sheltered from the colder extremes of the
continental weather systems, have been able to support plant life that
could not exist on the steppe. Areas along the Black Sea coast and in
valleys of the Rodopi that open to the south experience further
moderation. Many Mediterranean and subtropical species have existed in
them naturally, and others introduced by man have thrived.

What remains of the original vegetation on the Danubian plateau is found
mainly along the river, wh