154 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Jan. 13,
The sandstone forms the whole of the cliff from Ladraham Bay to
Budleigh Salterton, and on the left bank of the Otter it has, in parts,
a brecciated character.
At Budleigh a bed of quartzite-pebbles, the thickness of which has been estimated at about 100 feet, crops up from below the sand-stone, and rises westward to the top of the high cliff. This pebble-bed has been described by Mr. Vicary*, and the fossils of its pebbles by Mr. Salter†; so that no more need be said of it here.
Less than a mile from Budleigh a second thick mass of red marl occurs, and rises up from below the pebble-bed. In another mile a second bed of sandstone succeeds the marl, and forms the low headland of Straight Point‡, halfway between the Otter and the Exe.
At the point of the headland the sandstone contains a thin bed of fine breccia; and on the western side it is underlain by a bed of marl 20 or 30 feet thick, which is succeeded by sandstone with beds of marl, from below which again, as the cliff turns at right-angles westward, marl rises. This last contains a few beds of sandstone, is a thick mass, and occurs for some way further.
West of the "Highland of Oscomb" (on the Ordnance Map), where the cliff turns northward for a little way, another bed of sandstone crops up, and is soon underlain by a last bed of marl.
Westward a tract of blown sand hides the rocks; but just out of Exmouth there is a low cliff of sandstone, most likely the top part of the sandstone and breccia on the other side of the Exe; indeed Mr. Pengelly has shown§ that it must be so, from the fact that "in the undercliff, known as the 'Plantation,' below, and east of Beacon Terrace, the marl is found lying conformably on the conglomerate" (=breccia).
On the western side of the Exe we first meet with breccia, forming Langstone Point||, with its natural arches. Thence to Dawlish the cliffs are of sandstone with layers of breccia; and beyond this the latter increases at the expense of the former, until, north and south of Teignmouth, the cliffs are almost wholly formed of it. Of this singular thick mass of breccia, the lowest part of the "New Red" of Devon, Mr. Pengelly says, "We have in Torbay conglomerates [=breccias] and sandstones, with a few thin layers of marl. There is no very decided order of succession; but on the whole the sandstones may be said to preponderate. Wherever the base of the formation is seen, however, it consists of very coarse conglomerate. . . From Petitor ... to near Dawlish the cliffs consist of conglomerates, with a few beds of sandstone"¶.
In the above sketch, which is summarized in the section (fig. 2), no notice has been taken of the few faults that occur: these are nearly all very small, and none are of importance.
- Quart. Journ. Geol. Soc. vol. xx. p. 383.
† Quart. Journ. Geol. Soc. vol. xx. p. 386, and Geol. Mag. vol. i. p. 5.
‡ Not named on the Ordnance Map.
§ Trans. Plymouth Inst, for 1864-65, p. 34.
|| Not named on the Ordnance Map.
¶ Trans. Plymouth Inst. for 1862-63, pp. 15, 16.
