Correspondence — Prof. T. Rupert Jones. 287 



especially the British Islands. The absence of Lamellibranchiata in 

 rocks older than the Tertiary was noticed as having special interest 

 in the physical history of the Polar seas in Palseozoic and Mesozoic 

 times. None have ever been detected in these rocks. The authors 

 stated that they had sought also for evidence of Trias and Permian 

 fossils in this and other collections made, but there appeared to be 

 none. They also discussed the question of the deposition and exten- 

 sion of the Lias as represented at Eglinton Island and Spitzbergen, 

 The authors furnished a Table showing the distribution of all the 

 species collected by the expedition from twenty localities. 



coiaiaEsipoisriDEisroiB. 



SANJD-WOEN PEBBLES IN THE WEALDEN OF SUSSEX. 



Sir, — Being at Cuckfield lately, I obtained, by the kindness 

 of Mr. Henry Willett, F.G S., some of the large pebbles and sub- 

 angular pieces of quartz, quartzite, and lydite from the conglom- 

 erate, or pebbly and gritty bone-bed, of the "Upper Tunbridge- 

 Wells Sandstone" in the quarry at Whiteman's Green, near the 

 town. A glaze-like polish in parts of some of these stones at- 

 tracted my attention ; and, on looking at it with the microscope, I 

 discerned the delicate parallel striee which hloion sand produces in 

 polishing rocks and stones exposed to its action. 



One of these partially glazed stones from the Cuckfield grit has 

 also the triangular shape produced by the persistent action of blown 

 sand, and must have been long exposed to such influence on the 

 strand of the old Neocomian lake or estuary, before it was finally 

 imbedded among the grit and rolled bones. Notices of the con- 

 glomerate referred to above are given in Mantell's " Geology of tlie 

 South-East of England," 1833, p. 209, etc., and in the " Memoirs 

 Geol. Survey" (Topley's Weald), 1875, p. 93, and p. 187, note. 

 ToKKTOWN, April 10, 1878. T. KuPERT JoNES. 



THE PEESEEVATION OF DEPOSITS OF INCOHERENT MATERIALS 

 UNDER TILL OR BOULDER-CLAY. 



SiK,— Mr. S. V. Wood, in his " Keply " (Geol. Mag. Dec. 11. 

 Vol. V. p. 187), complains that I have not put the questions at issue 

 between us so incisively as he could have wished. I am sorry to 

 have so far disappointed my opponent, but it was not my intention 

 to controvert all his theoretical views. If he will look at the title 

 of my short paper, he will see that 1 confine myself to one point, 

 namely, the preservation of interglacial deposits. Mr. Wood has 

 so frequently denied the possibility of interglacial beds having been 

 overflowed by glacier-ice, and so confidently asserted that my views 

 were self-contradictory, that I thought it worth while to point out 

 that his principal, indeed his only, argument was based upon what 

 he himself tacitly admits is merely a preconceived notion. I am 

 glad to find, however, that in other respects his views approximate 

 to mine more nearly than he seems to be aware. Thus, he tells us 

 first, that he does not deny "that ice erodes more in some places 

 than in others ; " secondly, that he believes " some moraine accumu- 



