The Chemung beds are succeeded by a great series
of red sandstones and shales--the "Catskill Group"--which pass
conformably upwards into the Carboniferous, and which may perhaps
be regarded as the equivalent of the great sandstones of the
Upper Old Red in Scotland.
Throughout the entire series of Devonian deposits in North America
no unconformability or physical break of any kind has hitherto been
detected; nor is there any marked interruption to the current of
life, though each subdivision of the series has its own fossils.
No completely natural line can thus be indicated, dividing the
Devonian in this region from the Silurian on the one hand, and
the Carboniferous on the other hand. At the same time, there is
the most ample evidence, both stratigraphical and palaeontological,
as to the complete independence of the American Devonian series
as a distinct life-system between the older Silurian and the
later Carboniferous. The subjoined section (fig. 76) shows
diagrammatically the general succession of the Devonian rocks
of North America.
[Illustration: Fig. 76. GENERALIZED SECTION OF THE DEVONIAN ROCKS
OF NORTH AMERICA.]
[Illustration: Fig. 77.--Restoration of _Psilophyton princeps_.
Devonian, Canada. (After Dawson.)]
As regards the _life_ of the Devonian period, we are now acquainted
with a large and abundant terrestrial _flora_--this being the
first time that we have met with a land vegetation capable of
reconstruction in any fulness.
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