100 ME. R. L. SHERLOCK ON THE RELATIONSHIP OF THE [Feb. I9II, 



etc. (that is, it is of Keuper age). The late C. E. de Ranee thought 

 (Rep. Brit. Assoc. 1885, p. 384) that 



4 the pebbly character of the middle portion of the JBunter has died away 

 northwards, and that the Middlesbrough section represents Waterstones, 

 pebbleless Middle Bunter, and Lower Bunter.' 



Prof. Lebour's view is indicated by the classification tabulated 

 on the preceding page. 



Dr. Woolacott 1 has recently suggested a new classification of the 

 Permian of the North-East of England, which places 300 feet of 

 the Salt Measures in the Permian, and to this portion he gives the 

 name of ' Middlesbrough Red Beds with Salt.' 



Sir Andrew Ramsay, 2 referring in 1880 to Messrs. Bell Brothers' 

 trial-boring at Saltholme, stated that 1175 feet of red sandstones 

 and marls, with beds of rock-salt and gypsum, were passed through. 

 These strata he considered to be Keuper Marls and sandstones. 

 Beneath these came 67 feet of dolomitic limestone, which, he said, 

 in this neighbourhood forms the upper part of the Permian Series ; 

 and beneath the limestone the strata consist of 27 feet of gypsum, 

 rock-salt, and marls, one of the beds of rock-salt having a thick- 

 ness of 14 feet. Wilson 3 described the 67 feet of dolomitic lime- 

 stone as 'indurated marls,' and averred that they did not resemble 

 any known beds of the Magnesian Limestone of Durham, but had 

 the greenish-grey colour of certain Keuper Marls : therefore, he 

 referred the whole of the strata passed through in this boring to 

 the Keuper. Wilson thought it most improbable that the upper 

 part of the boring was in Keuper and the lower part in Permian, 

 because of the unlikelihood of an uncommon mineral, such as rock- 

 salt, occurring at two horizons, within 200 feet of one another 

 in the same vertical section, in two distinct rock-series. He added 

 that the chances against such a coincidence are vastly increased, 

 when we consider that there is no sort of sequence between the two 

 formations in the district in question, but that, on the contrary, 

 there is a decided break and unconformity between them — indicated 

 by the omission of the whole of the Bunter and Muschelkalk. He 

 also remarked that this discordance between Permian and Trias 

 in Durham is probably, in large measure, due to want of conformity 

 between the Keuper and the Bunter, coupled also perhaps with an 

 original northward thinning-out of the Bunter Sandstone. 



Mr. H. H. Howell, in 1890, gave his reasons for recommending 

 that all the red rocks, between the Rhaetic and the Durham 

 Permian limestones, should be classified as Keuper on the Geological 

 Survey maps. He states that he has examined the rocks which 

 underlie the undoubted Keuper at the few places where they crop 

 out from under the Drift, and that they have a distinctly Keuperian 

 aspect and are not in the least like Bunter. The cores of borings 



1 D. Woolacott, Eep. Brit. Assoc. 1909. 2 A. C. Ramsay, 1880, p. 11. 



3 E. Wilson, 1888, p. 771. 



