Page:Quarterly Journal of the Geological Society of London, vol. 25.djvu/247

1869.] WHITAKER—SOUTH-DEVON "NEW RED." 153 masses, that little is to be seen below the "White Lias" until we pass to the west of the great landslip of 1839 at Dowlands. The cliff is then clearer, and shows a set of evenly-bedded greenish clays, with black shales, stone-beds, and layers of hard marl (Rhaetic Beds). Here Mr. Pengelly found the well-known bone-bed. Lower down some of the layers of clay have a reddish colour; and there is a passage downwards into "New Red" marl, which has greenish layers in its top part. The beds rise westward in gentle waves, bringing up lower beds in that direction, and the green layers decrease in number downwards, until at the mouth of the Axe there are but a few thin ones, nearly all the marl being of the usual deep red. This section, therefore, shows a passage from the "New Red" into the Rhaetic Beds, and favours the view that the latter may be classed with the former just as well as with the Lias.

Leaving out these passage-beds, however, the red marl of Seaton is the uppermost part of the "New Red" of the South Devon coast; and it is, I believe, the only part that crops out along the cliffs west- ward to Sidmouth, where red sandstone rises up from beneath it in the cliff just east of the river. As the Greensand rests unconformably on the "New Red," it would be difficult, and perhaps impossible, to measure the thickness of the marl, and the more so as the section is much hidden by fallen masses.

This highest bed of marl does not come down to the sea-level westward of Sidmouth, and, indeed (except for a small patch noticed by Mr. Pengelly above the sandstone in Ladraham Bay),

Fig. 1.—View of High Peak from the East.

b. Greensand (overgrown, rough slope).

2. Red Marl, much furrowed by streams &c.

3. Red Sandstone, roughly bedded, much less furrowed.

ends off altogether in about a mile and a half. It forms, however, the greater part of High Peak, a fine mass, which is a good example of the way cliffs weather from above (fig. 1). The sandstone at the bottom is able to withstand the direct assault of the sea better than the marl above to resist the gentler attacks of subaerial actions; the marl is worn away into a number of furrows that mostly end at the top of the sandstone, which latter also forms a large isolated rock, surrounded by the sea (except at low water?).