In the same formation are found the fern (Figure
496) and the Lepidodendron (Figure 495), and other species of plants, some of
which, Professor Heer remarks, agree specifically with species from the lower
carboniferous beds. This induces him to lean to the opinion long ago advocated
by Sir Richard Griffiths, that the yellow sandstone, in spite of its fish
remains, should be classed as Lower Carboniferous, an opinion which I am not yet
prepared to adopt. Between the Mountain Limestone and the yellow sandstone in
the south-west of Ireland there intervenes a formation no less than 5000 feet
thick, called the "Carboniferous slate," and at the base of this, in some
places, are local deposits, such as the Glengariff Grits, which appear to be
beds of passage between the Carboniferous and Old Red Sandstone groups.
It is a remarkable result of the recent examination of the fossil flora of Bear
Island, latitude 74 degrees 30' N., that Professor Heer has described as
occurring in that part of the Arctic region (nearly twenty-six degrees to the
north of the Irish locality) a flora agreeing in several of its species with
that of the yellow sandstones of Ireland.
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