It has long been known that the Coniston Limestone Series of the English Lake District and surrounding areas is separable into minor divisions. As a knowledge of these will prove useful in settling the question as to the exact relation between the Couiston Limestone beds and the underlying rocks, no apology seems needed for giving a detailed account of the rocks of this series.

The literature of the subject is extensive, but we fortunately possess an excellent bibliography of works referring to the geology of the Lake District, in the appendix supplied by Mr. Whitaker to the late Mr. Ward's Memoir on the Geology of the Northern Half of the English Lake District.

The Landscape Marble or Cotham Stone is one of the best known of our English ornamental rocks. Polished slabs of it may be seen in most museums; and there are fashioned out of it paperweights, ring-stands, and other useful objects, which may be purchased on Clifton Down and elsewhere.

This stone came into notice when it was quarried, together with other beds, near Cotham House, on the northern side of Bristol; and it was described in considerable detail in 1754 by Edward Owen, who then gave it the name of “Cotham Stone.”

It is a hard, close-grained argillaceous limestone, which breaks with a fracture almost as conchoidal as that of flint; and it is characterized by dark arborescent markings which pervade the stone. These markings rise from a more or less stratified base, and terminate upwards in the wavy banded portion of the limestone, which varies from one to about nine inches in thickness. Thus when slabs, cut at right angles to the planes of bedding, are polished, there may often be discerned (with the aid of the imagination) a landscape with a prominent row of trees and bushes, with clouds above, and perhaps the semblance of water in the foreground.

During the summer of 1890, Professor Cole and I, whilst geologising in North Wales, were led to examine the Hirnant Limestone. Since then the further examination in the laboratory of the specimens collected by myself have revealed some remarkable characteristics which, as they are as yet undescribed, I think are worthy of notice.

The specimens on which the following observations have been made were obtained from a small cutting opposite to the farm named Cwm-yr-aethnen, in the valley of the Hirnant, which descends towards Bala Lake. The limestone occurs here between two beds of fossiliferous slate. The exposure is very small, and being considerably overgrown, it was only by careful search that we succeeded in finding it. The Survey Memoir mentions that an. outcrop occurs at Trum-y-gwrageda, and also that loose blocks were found by Sedgwick at the Bwlch-y-groes; but after a careful search we failed to find it at either of these localities.

The existence of rocks possessing, when the laminæ are not too thick, the property of flexibility has long been known. Upon flexible sandstone (“Itacolumite”) a great deal has been written at different times, and of late years important work has been done which renders it necessary to greatly modify the opinions formerly held with regard to this rock. Notwithstanding the interest which, is attached to the subject, it is one very much neglected by our textbooks, the British, either ignoring it altogether, or treating it with the utmost brevity, the German, while sometimes referring to it at considerable length, do not do more than enunciate the old views. To Prof. Judd—who has kindly aided me with advice, and by affording facilities for preparing this paper—I owe the suggestion that it would therefore be useful to give a résumé of the present state of our knowledge upon the flexibility of rocks in general.