Notices of Memoirs — 8ptirreU's West Kent Denudation. 121" 



Bryniau, and N.E.N, at Moel Hiraddug, so that it is greater than it 

 appears to be in the section. The highest subdivision, the Upper Black 

 Limestone, occurs at the north end, and the Upper Grey Limestone 

 crops out from under it, and extends to Nant-yr-ogof, where there is 

 a considerable fault, which brings up the top of the Lower Brown and 

 the base of the Middle White Limestone. From the fault the Middle 

 White extends three-quarters of a mile, when the Lower Brown Lime- 

 stone crops out, continues some distance, and forms the conspicuous hill, 

 Moel Hiraddug, on the top of which the lower beds of the Middle White 

 Limestone are again exposed. 



Along the west and parallel with the section there are two great 

 faults, known as the Prestatyn fault and the Yale of Clwyd fault, and 

 on the western side of the former a bare limestone hill, Graig-fawr, rises 

 to an elevation of 500 feet, and presents a grand exposure of the Middle 

 White Limestone, which is 600 feet in thickness. Numerous fossils 

 occur at the north end of Graig-f iwr, and a greater number has been 

 obtained there than from the Middle White Limestone anywhere else. 



On the west of the Carboniferous Limestone shown along the line of 

 section several faults, including the two already referred to, have 

 thrown down the limestone beneath the level of the sea, and the Lower 

 Coal-measures have been proved to occur at Meliden and Dyserth, 

 beneiith a deep covering of drift. In one of the recent " Memoirs of 

 the Geological Survey," by Mr. A. Strahan, M.A., F.G.S., a full 

 description of the Geology — Explanation of Quarter-sheet 79 N. W. — 

 will be found, with all the details of the drift and underlying strata. 



IIL — A Sketch of the History of the Eivers and Denudation 

 OF West Kent, etc. By F. C. J. Spurrell, F.G.S. 8vo. 

 Greenwich, 1886. [Reprinted from the Eeport of the West 

 Kent Natural History Society, 1886.] 



THE author commences with some remarks on the " plane of mai'ine 

 denudation " which was produced over the W^ealden area before 

 the present features were carved out by subaerial forces. He 

 observes that nowhere over the Wealden rocks is there to be found 

 any deposit belonging to that old marine age ; but it is quite 

 possible that the Pliocene deposits of Lenham, etc., may be relics 

 of the period. He then refers to the denudation by rain and rivers, 

 and the breaching of the Chalk Downs, and states that " On the 

 crest of the Downs there may be found in some places relics of the 

 rocks from the Weald, Gault Clay, Chert, Greensand, Sand and 

 Limestone, etc., lying on the Chalk, not in the condition of river 

 gi'avel, but of patches of the old beach." The gravel of Shooter's 

 Hill is, in his opinion, largely composed of the wreck of Bagshot 

 Beds, and there are many similar outliers of pebbly gravel. These 

 beds occur, as a rule, at a higher level than the Thames Valley 

 gravels, and they may be distinguished from them by the absence of 

 the erratic pebbles and fossils of northern origin (derived from 

 Glacial Drifts), that occur in the newer deposits. These Thames 

 Valley gravels, in Mr. Spurrell's opinion, lie below the 200 feet 

 contour-line, the highest elevation being at Wimbledon, 190 feet. 



