362 Rev. J. F. Blake — On the Red Chalk in Yorkshire. 



Generally speaking, this consists of fragments of silicified wood 

 about six inches in length, which are strewn over about four 

 miles of desert. Where the trunks from which they have been 

 derived are shielded from the sun by lying buried in the sand, and 

 have thus been protected from sudden changes of temperature, they 

 are often preserved in pieces several j^ards in length. When fissured, 

 they do so rather down the trunk than transversely to it, which would 

 seem to contradict Gardiner Wilkinson's suggestion,^ referred to by Mr. 

 Carruthers,^ that there are " some jointed stems resembling bamboo or 

 Equisetum." In the same paper it is stated that no branches were ob- 

 servable, which appears to be the case ; but I was assured on good 

 authority that at the New Petrified Forest a tree with the limb of 

 a large branch may be seen. The larger trees referred to may be 

 seen by taking a S.E. course towards a distant bluff across this 

 desert. After about a mile you reach the north end of a line of low 

 sand and gypsum hills, keeping along the eastern side of which 

 you shortly come upon numerous trunks lying in the sand, some of 

 which are 40 feet long and two feet in diameter. 



Beyond these, still continuing in a S.E. direction, through a gap 

 in the low sand-hills, for a quarter of a mile across the next open 

 valley, some extensive Oyster-beds are reached, from which some 

 perfect specimens may be obtained. 



On the opposite side of the Nile to that on which Cairo stands 

 are corresponding hills to those of Moccattam, in which are the 

 ancient quarries of Sattanah. At the Pyramids of Gizeh, which 

 are built of Nummulitic Limestone, the Sphinx is seen cut out of 

 the solid rock, and exhibits in the material composing it a natural 

 N.E. dip and the eroding effects of tens of centuries of sand-blast. 



V. — Note on the Eed Chalk in Yorkshike. 

 By the Eev. J. F. Elake, M.A., F.G.S. 



IN mapping the boundaries of the Lias in that part of Yorkshire 

 where the Cretaceous rocks overlap the Jurassic, the Eed Chalk 

 becomes extremely useful as a guide, especially as the springs con- 

 stantly break out beneath it, and give good opportunities for its 

 examination and that of the subjacent strata. Some points of in- 

 terest have thus obtruded themselves upon one's notice. Its range 

 in Yorkshire may be described as first northwards and then east- 

 wards. Though much covered by Boulder-clay in the latter por- 

 tion, it may be traced almost step by step along the former, except 

 where it appears to be absent. 



Mr. Judd ^ has drawn attention to the unconformity between the 

 Upper Cretaceous and Neocomian series, with which latter beds he 

 includes certain ferruginous pebbly beds which lie below the Eed 

 Chalk, and are generally unfossiliferous, but which contain towards 



1 Gardiner 'Wilkinson in "Murray's Handbook for Travellers in Egypt" (1867). 



2 "W. Carruthers, " On the Petrified Forest near Cairo," op. cit. p. 307. 

 ^ Quart. Journ. Geol. Soc. vol. xxiii. p. 242, etc. 



