336 Correspondence — Mr J. E. Taylor. 



The intercalation of a thin red band, largely composed of an- 

 hydrous sesquioxide of iron, between beds of such different physical 

 character, is difficult of explanation. The line of demarcation is 

 remarkably definite, no gradation existing between the red stratum 

 and the Gault above or the Lower Greensand below. — Geo. Maw. 



Benthall Hall, Eeosely, May 2Wi, 1869. 



SINGULAR SUBSIDENCE AT MARTOK 



Sir, — In reply to Mr. J. W. Wilson's description of a singular 

 subsidence at Marton, near ISTorthwich, perhaps I may be allowed to 

 remark that the phenomenon is not so rare as may be imagined. 

 When living in Cheshire I frequently heard of similar subsidences 

 taking place. These occurred in every instance on the Keuper forma- 

 tion, and I attributed them to the dissolving away of a good portion of 

 the rock salt, which frequently attains a thickness of nearly a hundred 

 feet, by the percolation of running water. Considering the vast 

 quantity of solid salt held in solution by the brine springs, this can 

 hardly be wondered at. I do not think, however, that the subsi- 

 dence of the surface usually takes place so suddenly. As a rule it 

 will be in the ratio of the dissolution of the underlying rock-salt beds. 

 It has frequently struck me that some of the small "Meres" in 

 Cheshire have originated under similar circumstances. In Norfolk 

 we frequently have subsidences of the surface by the dissohition 

 of chalk by sand-pipes. In many parts of Lancashire and Stafford- 

 shire the surface of the country sinks where mining operations are 

 carried on. This is best told by the great depth of the neighbouring 

 canals, whose banks have had to be built up in order to preserve the 

 level of the water. Near Dukinfield, the canal is in many places 

 over twelve feet deep — the depth being a good index to the amount 

 of subsidence undergone in consequence of the coal having been 

 worked underneath. Newspaper paragraphs relating the sudden 

 sinking of small areas are not rare in Norfolk, the usual vulgar ex- 

 planation of them being of course earthquake action. Eock salt is 

 much more readily soluble than Chalk, so that it is very probable 

 the subsidences in Cheshire and Norfolk are due to the similar action 

 of water in dissolving and removing the solid matter of the strata 

 beneath. J. E. Taylor. 



Norwich, June 13, 1869. 



iyLiso:EXiXj.i^isr:HioTJS. 



A Gigantic Oolitic Lizard. — Prof. Phillips has lately recorded 

 the discovery — in a quarry at Enslow Bridge, a few miles north of 

 Oxford — of the femur of a monstrous lizard of the Oolitic age, mea- 

 suring five feet and a third (sixty-four inches) in length, and 44*25 

 inches round the distal extremity ; while the breadth at the upper 

 end (taken obliquely) is 20-75 inches, and the circumference 46-0 

 inches. A similar bone (but not nearly so large) in the Oxford 

 Museum was referred by the late Hugh E. Strickland to Prof. 

 Owen's genus Cetiosaurus, to which genius no doubt this gigantic 

 femoral belonged. 



