Page:Transactions of the Natural History Society of Northumberland, Durham, and Newcastle-upon-Tyne (1867).djvu/62

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Of the slate rocks we have no large or characteristic development within our bounds, but we have, near at hand, in the Lake district, a very considerable range of hills, where beds of this class cover wide surfaces. Unlike the porphyry and basalt, the slate rocks exclude absolutely the special limestone plants; but like the porphyry and basalt, they are much less heathery than the sandstone, with but little peat upon their surfaces, and with clear transparent streams, and some of the pascual plants do not ascend so high amongst them as with the limestones. But on the other hand, as they rise to a greater height than the hills formed of any of the other three kinds of rock, and present a greater variety of surface in the Upper zone, many plants ascend higher amongst them than anywhere on the east side of the island, and they furnish several boreal plants which we do not get in the east at all. For comparison with the two upper zone florulas already enumerated, we give one for a characteristic crag of the slate formation, and have selected for that purpose a list of species noted on the face of the well-known Striding Edge cliff, which rises from the banks of the Red Tarn, on the west side of Helvellyn, at an elevation above sea level of from 800 to 950 yards.