he sand of the desert are
still in process of formation, the accumulation of these deposits
probably began in the Tertiary period.

_Volcanic Rocks._--Amongst the Archean rocks granitic and other
intrusions are abundant, but of more modern volcanic activity the
remains are comparatively scanty. In south China there is no evidence
of Tertiary or Post-Tertiary volcanoes, but groups of volcanic cones
occur in the great plain of north China. In the Liao-tung and
Shan-tung peninsulas there are basaltic plateaus, and similar
outpourings occur upon the borders of Mongolia. All these outbursts
appear to be of Tertiary or later data.

_Loess._--One of the most characteristic deposits of China is the
loess, which not merely imparts to north China the physical character
of the scenery, but also determines the agricultural products, the
transport, and general economic life of the people of that part of the
country. It is peculiar to north China and it is not found south of
the Yangtsze. The loess is a solid but friable earth of
brownish-yellow colour, and when triturated with water is not unlike
loam, but differs from the latter by its highly porous and tubular
structure. The loess soil is extremely favourable to agriculture. (See
LOESS and _infra, Sec. Agriculture._)

The loess is called by the Chinese _Hwang-t'u_, or yellow earth, and
it has been suggested that the imperial title _Hwang-ti_, Yellow
Emperor or Ruler of the Yellow, had its origin in the fact that the
emperor is lord of the loess or yellow earth.

Structure.

Structurally, China proper may be divided into two regions, separated
from each other by the folded range of the Tsing-ling-shan, which is a
continuation of the folded belt of the Kuen-lun. North of this chain
the Palaeozoic beds are in general nearly horizontal, and the
limestones and sandstones of the Sinian and Carboniferous systems form
an extensive plateau which rises abruptly from the western margin of
the great plain of northern China. The plateau is deeply carved by the
rivers which flow through it; and the strata are often faulted, but
they are never sharply folded. South of the Tsing-ling-shan, on the
other hand, the Palaeozoic beds are thrown into a series of folds
running from W. 30 deg. S. to E. 30 deg. N., which form the hilly region
of southern China. Towards Tongking these folds probably bend southwards
and joi