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Description of the Section of the Upper Green-Sand at the Undercliff, in the Isle of Wight
Published online by Cambridge University Press: 17 March 2016
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The next division, 8th, consists of a bed of fawn-coloured sandstone of about ten feet in thickness, containing nodules of rag, with Pectines, Terebratulæ, Rhynchonellæ, &c., in the lower portion, which, owing to its softness and looseness of texture, the weather wears away, leaving the shells finely exposed. It is chiefly owing to such excavation of this bed, by the combined influence of the elements, that those great falls of the superincumbent masses have taken place at intervals along the line of the Undercliff, many such “founders” having happened within the memory of residents, and others being likely to occur constantly from this hard and solid mass of strata resting on an insecure foundation, the effects of which are still further increased by the presence of the Gault below.
But a few years back a large mass near Blackgang thus assumed such a dangerous and threatening attitude, by the lower part of it being so much worn away, that the authorities blew it down with gunpowder. Many thousand tons of rock and debris were thus thrown down, completely blocking up and destroying the original road; one huge mass still stands close to the road, as large and as high as a good-sized cottage.
A layer of rag-stone, called the “Big Rag-bed,” containing fossils, terminates what is termed the “sandstone-group.”
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- Copyright © Cambridge University Press 1858
References
* Gore Cliff, below which occurred the great landslip, in the month of February, 1798, when, during a severe frost, an entire tract of land, on which was a farm, called Pitlands, became separated from the Cliff, and descended towards the sea, burying the farm-house and carrying with it in its progress rocks, trees, and herds. In a letter dated Niton, Feb. 9th, 1799, in the “Isle of Wight Magazine” for that year, an account is given of this catastrophe:—” Dear Sir,—Yesterday I was desired by your tenant, farmer Harvy, to go down to Pitlands, to take a view of your cottage there, in order to communicate to you what follows. About Tuesday last, the whole of the ground from the Cliff above was seen in motion. which motion was directed to the sea, nearly in a straight line. Harvy perceived the house to be falling, and took out the curious antique chairs. The ground above beginning with a great founder at the base of the Cliff, immediately under St. Catherine's Down, kept gliding forward, and at last rushed on with violence, totally changing the surface of all the ground to the west of the brook that runs into the sea, so that now the whole is convulsed and scattered about, as if it had been done by an earthquake. Of all the rough ground, from the cottage upward to the base of the Cliff, there is scarcely a foot of land but what has changed its situation! the arable fields are likewise convulsed, but not to the degree that the rough ground is; as far as the fence is from the Chale side, the whole may be called one grand and awful ruin. The cascade which you used to view from the house at first disappeared, but has now broken out and tumbled down into the withey-bed, of which it has made a lake; this last appearance is owing, I suppose, to the frost, which preven's the water from running off. The few trees by the cottage, at the base of the rock on which you had placed a seat, have changed their situation, but are not destroyed. Harvy wanted, when I was there, to go into the house to fetch some trifling articles, but I dissuaded him; and very well I did, for soon after the wall to the west sunk into the ground. What damage is done, besides that which the house has suffered, I cannot say. The whole surface, however, has undergone a complete change; and at present there are everywhere chasms that a horse or cow might sink into and disappear. This seems to be an eventful period with us. Where your property is, there is a founder from the top of the Cliff, in that piece of land which Dixon rents, that has nearly covered the whole with fragments of free-stone.”