CHAPTER VIII.
THE GENERAL FEATURE OF THE CLIFFS CONSIDERED—CAUSES OF IRREGULARITY, AND THE GEOLOGICAL STRATA COMPOSING THEM.
The cliffs [55] extending from Hasborough to or a little beyond Cromer, are found, upon approaching near, to be extremely irregular. In some places small promontories or points project, in others small bays are formed, according to the influence of the sea, and the materials composing their structure. Their perpendicularity is partially averted from the fallen masses deposited at their base; which, where the cliffs are lofty, are often considerable; arising either from the sand or clay beneath the more solid strata being removed; or the landslips which ensue, from fresh water springs abounding in certain localities. Thus, in the winter of 1825, a fallen mass was precipitated from near the light-house at Cromer, which covered twelve acres, extending far into the sea, the cliffs being two hundred and fifty feet in height; and Mr. Lyell observes, the undermining by springs has caused large portions of the upper part of the cliffs, with houses still standing upon them, to give way, so that it is impossible, by erecting breakwaters at the base of the cliffs, permanently to ward off the danger.
The wasting of the cliffs is also accelerated from other causes—the continuation of strong north-easterly winds, of drought producing fissures from their superior surface downwards, heavy rains, and after severe and successive frosts.
The cliffs generally consist of clay, sand, and loam. By some writers they have been termed mud cliffs, from their dark colour and general appearance. Mr. Lyell includes them in a series called the Boulder formation.
Mr. Woodward, in his Outline of the Geology of Norfolk, considers them to be of diluvial origin; but upon close inspection, they are found to contain strata and fossils which partake of the characters and may be ascribed to various parts of the tertiary period.
The cliffs form part of an extensive series, extending from Hasborough Lighthouses to Weybourne, north-west of Cromer, comprising a distance of about twenty miles, and are supposed continuously to rest upon chalk.
In some places the cliffs are very regularly stratified, presenting at various parts, layers of red and white sand, but in other places they are wholly devoid of stratification, exhibiting one continuous mass of till.
This position of the various strata will be found pretty correct:—
Tertiary | ||
Diluvial | 1 Brown clay: containing bones of the horse,ox, &c. 2 Till | |
Newer Pliocene | 3 Crag 4 Fresh water, lacustrine, lignite, &c. | |
Older Pliocene | 5 Blue clay 6 Red gravel | containing bones of elephants, rhinoceros, &c. |
Eocene | 7 Green sand: with bones of extinctmammalia. | |
| 8 Chalk | |