Page:Quarterly Journal of the Geological Society of London, vol. 31.djvu/91

Rh IN THE ISLE OF PORTLAND AND AROUND WEYMOUTH. 45 coast, in the Channel Islands, and on the coast of Cotentin, says of them : — " These beds, wherever found, are remarkably uniform in their general appearance and composition : they consist of fine earthy matter, such as would result from the decomposition of the rocks of the place ; mixed with this are fragments of rocks of all sizes, ranging up to blocks of considerable dimensions : the fragments are obviously smaller in the upper portion of these accumulations than in the lower. In places where the slope of the land is at a small angle, the " head " is mostly earthy, and of small amount ; where it is steep, or rocky, it becomes in proportion thick and fragmentary : the component fragments will, in this case, be seen to have been derived in every instance from the masses of rock immediately over- hanging — the materials are always strictly local as to origin. " These accumulations, as seen in cliff-sections and at short dis- tances, present an appearance of horizontal arrangement; closer examination, however, shows that this has nothing of the character of subaqueous arrangement : another very obvious feature is, that the fragments are all perfectly sharp and angular — no specimens of included waterworn rock are ever found." After a general survey of the whole area, Mr. Godwin- Austen concludes that they are of subaerial origin, and are due to the action of great cold — not neces- sarily that of a glacial period, but arising from elevation of the land ; and he thus tersely sums up : — " These phenomena so exactly accord with what is to be observed in all regions of excessive temperatures, whether resulting from geographical position or from altitude, they are so totally beyond the power of any present agencies, that it seems absolutely necessary to call in the operation of cold to adequately account for them. Many considerations oppose the possibility of low temperature along the parallel of 50° N.E., whence these observa- tions have been derived ; and the only physical condition which I can imagine sufficient to account for the fragmentary detritus generally of the whole of those areas from which I have borrowed illus- trations, is that of an elevation of great amount, such as would place the whole of the higher portions of this country in regions of excessive cold." At about the same period I described a similar deposit at Sangatte Cliff* much in the same terms as regards its composition as Mr. Godwin -Austen, but came to the conclusion, after examining this and also the Brighton bed, that the acting force had been subaqueous rather than subaerial, and that it was of short duration and violent ; but I did not then venture to speculate on the causes which led to the result or the exact mode of operation. At that time neither Mr. Godwin-Austen nor I had detected any shells in these beds. I subsequentlyf found land-shells of the most delicate structure in the Sangatte deposit. While in the main I agree with my friend as to the condition of the debris, I do not agree with him on some points of structure. So rii. p. 274, 1851. t Quart. Journ. Geol. Soc. vol. xxi. p. 440, 1865.
 * " On the Drift at Sangatte Cliff, near Calais." Quart. Journ. Geol. Soc. vol.