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706 - STRATIGRAPHICAL GEOLOGY. — [Boox VI. 
As a whole they are unfossiliferous, but they have yielded some ferns 
like those of the Upper Old Red Sandstone of Ireland and Scotland 
(Palzopteris), some characteristic genera of fish, as Holoptychius and 
Bothriolepis, and a large lamellibranch closely resembling the Irish 
Anodonta. The Old Red Sandstone development, found on the eastern 
side of the crystalline ridge which runs southward from Canada far into — 
the States, is described at p. 718. 
II. OLD RED SANDSTONE TYPE. 
§ 1. General Characters. 
Under the name of Old Red Sandstone is comprised a vast and 
still imperfectly described series of red sandstones, shales, and con- 
slomerates, intermediate in age between the Ludlow rocks of the 
Upper Silurian and the base of the Carboniferous system in 
Britain. These rocks were termed “Old” to distinguish them 
from a somewhat similar series overlying the Coal-measures, to 
which the name “New” Red Sandstone was applied. When the 
term Devonian was adopted, it speedily supplanted that of Old Red 
Sandstone, inasmuch as it was founded on a type of marine strata of 
wide geographical extent, whereas the latter term described what 
appeared to be merely a British and local development. For the 
reasons already given, however, it is desirable to retain the title Old 
Red Sandstone as descriptive of-a remarkable suite of deposits to 
which there is little or nothing analogous in typical Devonian rocks. 
The Old Red Sandstone of Europe is almost entirely confined to the 
British Isles. It was deposited in separate areas or basins, the sites 
of some of which can still be traced. Their diversities of sediment 
and discrepance of organic contents point to the absence, or at least 
rare existence, of any direct communication between them. It was 
maintained many years ago by Mr. Godwin Austen, and has been — 
more recently enforced by Sir A. C. Ramsay, that these basins were 
lakes or inland seas. ‘The character of the strata, the absence of 
unequivocally marine fossils, the presence of land plants and of 
numerous ganoid fishes which have their modern representatives in 
rivers and lakes, suggest and support this opinion, which has been 
generally adopted by geologists. The red arenaceous and marly 
beds which, with their fish remains and land plants, occupy a depth 
of many thousand feet between the top of the Upper Silurian and 
the base of the Lower Carboniferous systems, are regarded as the 
deposits of a series of lakes or inland seas formed by the uprise of 
portions of the Silurian sea-floor. The length of time during which 
these lacustrine basins must have existed is shown, not only by the 
thickness of the deposits formed in them, but by the complete 
change which took place in the marine fauna between the close of the 
Silurian and the commencement of the Carboniferous period. ‘The 
