measures
are Palaeozoic. Dr. Feistmantel maintains, however, that the Australian
upper coal-measures are triassic, while the lower are undoubtedly
carboniferous, Glossopteris having survived. Some of the Australian sections, however, scarcely support the view of a distinct separation being possible.
Mr. W. T. Blanford is of opinion that
The
whole evidence, so far as it goes, both of animals and plants, tends to
connect the whole of the Gondwana series with formations ranging from
the upper Palaeozoic (Permian) to the lower Jurassic.
It is clear that floras alone
afford but an unsafe guide to correlation, and for this reason, that
they, as well, also, as some land animals, appear to have often
survived the wholesale changes which have affected the faunas of the
neighbouring seas and oceans.
Although,
therefore, it may be dangerous to attempt a close correlation of the
Indian formations with those of distant countries by the evidence
afforded by fossil plants, still the advantage of employing such
evidence as a means of identification between widely-separated deposits
within the limits of India cannot be doubted.
Origin of the Gondwana Rocks.—From
the evidence afforded by the fossils, and the lithological characters
of the rocks, it is probable that the Gondwana strata were deposited in
a series of river valleys not unlike those which constitute the
Indo-Gangetic plains at the present day. The rivers were generally
sluggish in their movements and occasionally may have formed lakes.
Areas of Gondwana Rocks.—The following Table of the areas of the Indian coal-measures and associated
F
