Correspondence — A. M. Davies. 331 



gabbro-Hke type to the finest schists, and some of the rocks are 

 vesicular. The rocks are frequently foliated. 



The crush-conglomerates have been observed in the limestones, 

 quartzites, and epidiorites ; but they are most conspicuously developed 

 at the junction of rocks of dissimilar character, and especially when 

 the limestone and epidiorite are in juxtaposition. The junction of 

 the two rocks is intricately folded : folded knobs of epidiorite 

 measuring from a few inches to a foot or more being packed 

 together in a limestone matrix. In the sections big blocks may 

 be seen in process of division by shearing movements, which have 

 succeeded the folding. The limestone seems generally to have 

 played the part of a plastic body, and has accommodated itself 

 as a matrix to the folded and isolated fragments of epidiorite, 

 between which it has been squeezed. Thus the origin of the 

 conglomerate is satisfactorily proved by the fact that it contains 

 fragments of rocks newer than the sediments in which the crush- 

 conglomerates are embedded. The author considers that it would be 

 safer to regard such conglomerates in this area as have a calcareous 

 matrix as having been formed by crushing. 



THE MAMMILLA TirS-ZOl^'E IN EAST SURREY. 



SiE, — In a short communication to this Magazine for May, 1899 

 (pp. 234-5), evidence was brought forward of the persistence of the 

 zone of HopUtes interruptns along the Gault outcrop through Kent 

 and Surrey. Since then Mr. Jukes-Browne's valuable memoir on 

 the English Gault and Upper Greensand has appeared, and in this 

 certain beds at the extreme base of the Gault in West Kent and 

 East Surrey are considered as probably belonging to the lower zone 

 of Acanthoceras mammillatum, though palaiontological evidence of 

 this is wanting. This evidence can now fortunately be supplied. 

 About a mile and a half south-south-east of j\Ierstham, at a point 

 marked on the new 1-inch sheet 286 as " Stocklands Farm," there is 

 a small brickfield where the extreme base of the Gault is dug. The 

 junction with the Folkestone sands is not actually seen, but these 

 sands are dug within a few yards of the section. In the lowest 

 part of the clay there are abundant large and irregular phosphatic 

 nodules, full of glauconite grains and with many quartz-grains also. 

 In these nodules fossils occur, including two species of Ammonites, 

 Acanthoceras mammillatum and Desmoceras Beudanti, the latter being 

 particularly abundant. (These determinations have been kindly 

 verified by Mr. Crick, of the Natural History Museum.) Other 

 fossils occur, but not abundantly, and I cannot give a list, as most 

 of them were dispersed among a party of my students before the 

 special interest of the section was discovered. Coniferous wood 

 occurs abundantly, beautifully preserved. 



The section is closely similar in appearance to one at Reigate, 

 described in Proc. Geol. Assoc, vol. xvi, p. 162, and there said to 

 be unfossiliferous. On a recent visit, however, I found a piece of 



