Page:A Treatise on Geology, volume 1.djvu/192

 176 are numerous. Agassiz (1843) enumerates

From this general review, the reader will infer that most of the forms of plants and animals of the carboniferous system are very distinct from existing types, but yet comparable with them and intelligible by them; but that genera are mixed with them, which cannot be, or at least have not been, at all discriminated from recent; and among plants in particular, some fossil forms (ferns) have a resemblance to recent species which is quite surprising.

Physical Geography.—Much of the most picturesque contracted scenery of England is situated among the deep-cleft valleys and rock-breasted hills of the mountain limestone, which, in Cheddar cliffs, on the banks of the Wye, in Derbyshire, the Yorkshire dales, and parts of Cumberland, Westmoreland, Lancashire, Flintshire, and Glamorganshire, offers most attractive features to the artist. In Ireland, this rock is the source of very fine effects, about Sligo and Enniskillen. The Meuse flows from Namur to Huy through a succession of precipices of limestone comparable to those of the Wye, Coal deposits are generally found in countries deficient of beauty of form and luxuriance of vegetation; yet the undulations of the large coal tracts of Yorkshire and South Wales, with the noble oak woods which fill some of the valleys, are worthy of notice.

The millstone grit and Yoredale rocks form in the north of England a peculiar order of scenery; for resting in detached masses upon broad, bare surfaces of scar limestone, their bold craggy tops and edges, and abrupt precipices, produce often a grand, though sometimes a formal effect, and their combinations are frequently fine. To this country belong also many beautiful waterfalls, originating in the decay of soft shales