chists. On the northern flank the folded beds are
followed by a zone of Jurassic and Cretaceous beds which rapidly
assume a gentle inclination towards the plain. On the south the
corresponding zone is affected by numerous secondary folds which
involve the Sarmatian or Upper Miocene deposits. In the eastern part
of the chain the structure is somewhat modified. The crystalline band
is lost. The northern Mesozoic zone is very much broader, and is
thrown into simple folds like those of the Jura. The southern Mesozoic
zone is absent, and the Palaeozoic zone sinks abruptly in a series of
faulted steps to the plain of the Kura, beneath which no doubt the
continuation of the Mesozoic zone is concealed.

[Illustration]

The geological sequence begins with the granite and schists of the
central zone, which form a band extending from Fisht on the west to a
point some distance beyond Kasbek on the east. Then follow the
Palaeozoic schists and slates. Fossils are extremely rare in these
beds; _Buthotrephis_ has long been known, and doubtful traces of
_Calamites_ and ferns have been found, but it was not until 1897 that
undoubted Palaeozoic fossils were obtained. They appear to indicate a
Devonian age. Upon the Palaeozoic beds rest a series of Mesozoic
deposits, beginning with the Lias and ending with the Upper
Cretaceous. Whether the series is continuous or not is a matter of
controversy. F. Loewinson-Lessing states that there is a more or less
marked discordance between the Lias and the Upper Jurassic and between
the latter and the Cretaceous; E. Fournier asserts that there exists a
very strongly marked unconformity at the base of the Tithonian, and
other writers have expressed other views. In general the Upper
ajurassic beds are much more calcareous on the north flank of the
chain than they are on the south. The Mesozoic beds are followed by
the Tertiary deposits, which on the north are nearly horizontal but on
the south are in part included in the folds--the Eocene and Miocene
being folded, while the later beds, though sometimes elevated, are not
affected by the folding. The final folding of the chain undoubtedly
occurred at the close of the Miocene period. That there were earlier
periods of folding is almost equally certain, but there is
considerable difference of opinion as to their dates. The difference
in character of the Jurassic beds on the two sides of