476 Correspondence — Mr, S. B. J. Skertchly. 



coI^I^:E!SI^OI^^z^:Bl^^c:E. 



INTER-GLACIAL MAN. 



Sir, — Will you allow me to record the discovery of Palseolithic 

 flint implements, mammalian bones, and fresh-water shells in brick- 

 earths below the Boulder-clay of East Anglia ? 



The great chalky Boulder-clay of this district I have shown in 

 two Geological Survey Memoirs, now in the press, to belong to the 

 early part of the Great Ice Age, and only to be " Upper Glacial " in 

 so far as this district is concerned. Beneath this clay occur patches 

 of brick-earth which may be of '' Middle Glacial " age or even older, 

 and from them I have obtained well -fashioned flint implements. 

 These tools are the oldest yet described, although some of the well- 

 known cave implements may be as old or older, their antiquity 

 being doubtful, from the absence of Glacial deposits. The human 

 remains from the Victoria Cave at Settle, beneath Glacial Clay, are 

 in all probability of the same age as our Palseolithic gravels^ and 

 hence much newer than those in question. 



I hope shortly to describe these interesting relies and their geo- 

 logical position fully. Sydney B. J. Skertchly. 



H. M. Geological Survey, Brandon, 

 September 1st, 1876. 



THE STAINING OF ROCKS BENEATH THE MAGNESIAN LIMESTONE. 



Sir, — Immediately below the Magnesian Limestone of Yorkshire 

 there is a belt of shales and sandstones more or less red or purple 

 in colour. For a long time these rocks were looked upon as a sub- 

 division of the Permian Group, the main reason for placing them 

 on that horizon being their marked red hue, which contrasts strongly 

 with the blue or grey tints of the generality of the Carboniferous 

 shales and sandstones. It is now, however, well known that these 

 red beds are stained Carboniferous rocks, and as the staining is con- 

 fined to the portions which are now capped by Magnesian Limestone, 

 or which were probably once overlaid by that formation, there is 

 good ground for believing that the Magnesian Limestone has had 

 something to do with the change in colour. It seems likely that 

 the eff'ect has been produced by water, which has percolated through 

 the Limestone and passed down into the stained rocks.^ 



In the hopes of throwing some light on the nature of the chemical 

 reactions by which the change in colour has been brought about, I 

 made the following experiment : Water saturated with carbonic acid 

 gas, and containing finely divided limestone, was dropped slowly on 

 lumps of gritstone in such a manner that very small quantities of 

 the powder dropped at the same time. After the process had been 

 continued for about six weeks, the stone was found to be stained dark 

 red, and the staining was particularly marked in the bluish grey 

 varieties. The quantity of the colouring matter was too small to 

 all@.w Of its being analysed, but it seemed to me likely that some salt 



1 J. C. Ward, Quart. Journ. Geol. Soc. vol. xxv. p. 295 ; Geol. Mag. Vol. IX. 

 p. 389. J. Lucas. Geol. Mag. Vol. IX. p. 338. For another case of rock staining 

 see Mems. of Geol. Survey of Great Britain, vol. i. p. 45. 



