until we pass the border of Dorsetshire, just beyond Lyme Regis, and enter Devonshire, where the high cliffs are broken by the great range of landslips that add so much to their beauty. The sections here have been described by Sir H. De la Beche * ; and from his account of the Chalk seen near Lyme it appears that the lower, or flintless, division is thin, having a thickness indeed of not more than 40 feet, whilst the lowermost 50 feet of the Upper Chalk contains fewer flints than the overlying part, in which they are frequent. I cannot understand, though, how so great a thickness as 20 feet is given by him to the Chalk with quartz -grains, unless, as seems likely, the whole of the Chalk Marl is therein included.
In the Chalk with flints at Pinhay † &c. there are brown hard nodular layers, weathering to a rough surface, as at "White Nore, east of Weymouth. In the undercliff fallen masses show the junction of the Chalk and the Greensand, the bottom of the former consisting of a hard buff nodular bed, with dark grains and quartz-grains, from 2 to 3 feet thick, above which, for from 2 to 4 feet, the Chalk has irregular masses of the same brown nodular character, and also the distinctive grains. Here, indeed, it is often hard to mark the junction ; the Chalk gets nodular, darker, and harder, until it seems almost one mass with the Greensand.
Near the cliff-top just east of Charton, the junction may be seen in place, the same two beds occurring, and the upper of them passing up into white chalk with hard brownish nodular lumps, which (8 or 10 feet above the greensand) form a projecting bed about 1-1/2 foot thick. Some of the quartz-grains here are larger than those in the country to the east.
At the western end of the Dowland's landslip the bottom six feet of the chalk are hard, quartz-grains occur therein, and the lower part is slightly darker and compact.
At the mouth of the Axe the bed with quartz-grains is about three feet thick and contains fossils.
The section near Beer has also been described by Sir H. De La Beche ; but something may be added to his account. The chalk- with-flints of "White Cliff contains hard buff nodular layers (as elsewhere), and its bottom part has fewer flints than the rest. The chalk without flints also contains hard nodular layers, and is of comparatively small thickness, perhaps thirty feet ; the lowermost three feet or so are the same as to the east.
Westward of Beer Head the bold cliffs, here separated from the sea by a fine undercliff, give a most interesting section, part of which shows a thinning-out of the Lower Chalk, and consequently the direct superposition of Upper Chalk on Upper Greensand — an occurrence which I believe has not been before noticed in this country. This junction is inaccessible, and can be seen only from below, and then, from the roughness of the cliff, not with the greatest ease. In fig. 2 it has been thrown into the form of a diagram, as it would
- Trans. Geol. Soc. ser. 2, vol. ii. p. 110, and " Report on the Geology of
Cornwall, Devon, and West Somerset," p. 237.
† Pinney on the Ordnance Map.
VOL. XXVII. PART I. H
