12 H. H. Howell — Red Rocks in S.E. Durham. 



74 feet of superficial clay and gravel, next through about 1175 feet 

 of Red Sandstones and Marls with beds of rock-salt and gypsum. 

 The whole of these strata (excepting the clay and gravel) evidently 

 belong to the Keuper Marls and Sandstones of the upper part of 

 our New Eed series. Beneath these they passed through 67 feet of 

 dolomitic limestone, which in this neighbourhood forms the upper 

 part of the Permian series, and beneath the limestone the strata 

 consist of 27 feet of gypsum and rock-salt and marls, one of the 

 beds of rock-salt having a thickness of 14 feet. This bed of 

 Permian Salt is of some importance, since I have been convinced 

 for long that the British Permian strata were deposited, not in the 

 sea, but in salt lakes comparable in some respects to the Great Salt 

 Lake of Utah, and in its restricted fauna to the far greater salt lake 

 of the Caspian Sea." 



I do not think the late Director-General ever saw the cores of the 

 strata passed through in the Saltholme boring, but I examined them, 

 and I think he must have formed his opinion from the recorded 

 section and my description of them, and also from analyses of two 

 samples of the limestones, one taken from the bed at the depth of 

 1261 feet, and the other at a depth of 1320 feet. These analyses 

 were kindly given to me by Mr. T. Hugh Bell for the use of the 

 Geological Survey, and I showed them to the late Director-General 

 who visited me in his official capacity when 1 was resident in 

 Darlington. 



Mr. Edward Wilson is not inclined to admit the Permian age of 

 these " limestones " and the salt- bed which has been proved 

 beneath them. He demurs to the use of the term " limestone " as 

 applied to the whole of these beds, and designates them instead 

 " indurated marls." He adds, " Although there appear to be 

 dolomitic or calcareous, as well as dark bituminous beds among 

 them, they show no sort of resemblance to any known beds of the 

 Magnesian Limestone of Durham ; on the other hand, they possess 

 the characteristic greenish colour of certain Keuper Marls, as well 

 as a similar texture, and probably also mineral composition, although 

 decidedly harder than most of the rock of that series." On these 

 grounds Mr. Wilson classes these strata with the Keuper division 

 of the Trias. 



I append the analyses, of what I believe to be fair samples of the 

 strata bored through at the depths above mentioned, and they seem 

 to me to be something more than "indurated marls." 



Sample of Magnesian Limestone from the bore-hole (Saltholme), 1261 feet: — 



Carbonate of lime ... ... ... ... ... ... 54-71 



,, ,, magnesia 41-18 



Silica 

 Alumina 

 Water 

 Bitumen 



■81 

 2-00 

 trace 



ros 



■22 

 100-00 



