156 ON SECTIONS IN THE LOWER PERMIAN KOCKS 



district*. In this paper I desire to add some features of 

 interest to the description of the Claxheugh section, and to 

 give an explanation which is more in accordance with the 

 evidence obtained from the study of the rocks of the district. 



Dr. Trechmann has shown that a thick bed of anhydrite is 

 interbedded with the main mass of the Magnesian Limestone 

 at Hartlepool f, and suggests that anhydrite and gypsum were 

 interstratified in other areas with that bed from which it has 

 been subsequently removed. This would lead to a collapse 

 of the rock, and thus some of the disturbance and brecciation 

 of the Limestone, especially in its upper layers, may be due to 

 that cause. It is also probable that the removal of the sulphates 

 would enable the horizontal pressures that subsequently acted 

 to produce much greater disturbances and brecciation than 

 they would have on a rock that had not been rendered 

 cavernous in that way. In my paper on " The Stratigraphy 

 and Tectonics of the Permian " I state that sulphates and 

 other salts were probably laid down with the main mass of 

 the Magnesian Limestone, but as there was no direct evidence 

 in the North of Durham of such deposition, and as I knew 

 that Dr. Trechmann was working on the anhydrite deposit 

 near Hartlepool, it seemed to me best not to lay too much 

 stress on the probability of sulphates having been originally 

 present in the Middle and Upper beds of the Limestone, 

 until their occurrence at Hartlepool had been definitely proved 

 in these horizons. J 



The breccias occurring in the Permian of the North of England 

 have been produced in various ways, among which are: — 

 {a) The Brochrams of the Vale of Eden were screes probably 



* Proceedings of the University of Durham Philosophical Society — On 

 a case of thrust and crush brecciation, Memoir No. i, 1909, il'id 1912, 

 Stratigraphy and Tectonics of the Permian of Durham (Northern area). 

 Proceedings of Geologists' Association, London; 1912 — Geology of North- 

 East Durham and South-East Northumberland. 



t Quart. Journ. Geo). Soc, 1913. 



J Beds of anhydrite and gypsum liave since been proved to occur 111 the 

 Permian of South Yoritshire by borings through it. 



