158 ON SECTIONS IN THE LOWER PERMIAN ROCKS 



water as stated in my former paper. They present many of 

 the features that I Iiave described as occurring in the 

 Marsden district, and are speciall-y interesting because of the 

 masses of rock whicli can be shown to be thrust out of 

 position. That the thrusting, of which the roclcs of Claxheugh 

 and Down Hill give such clear exposures, took place over 

 large areas is evident from the sections of the Permian in 

 CuUercoats Bay, Marsden, etc., and from the exposures of 

 the Coal Measures along the south coast of Northumberland^. 



The rocks seen in the two areas are in descending order 

 (i) The Shell or ■F'ossiliferous division forming the Bryozoa 

 Reef, which runs in a series of knolls from the north to south 

 of Durham (2) The Lower or regularly-bedded Limestone 

 (3) The Marl Slate and (4) The Yellow Sands resting 

 unconformably on the Coal Measures. 



It is not proposed to describe these beds here as their 

 features have been fully given in the papers referred to, but 

 to give a short description of the structural features of the 

 two areas. 



The Claxheugh section will be understood from the photo- 

 graph and detailed drawing of itf. It affords evidence at the 

 western end of the exposure of the thrusting of the Lower 

 Limestone (3a) over the unbedded limestone of the Reef. 

 These disturbed beds are seen in the railway cutting 

 immediately above Claxheugh rock. Howse and Kirkby 

 collected Lower Limestone fossils from this place some 50 years 

 ago. At the eastern end the Marl Slate and Lower Limestone 

 are entirely thrust out of the section, and at X the Yellow Sands 

 have been sheared and dragged up over a mass of breccia 

 from west to east, thus affording evidence of the direction of 

 the thrust movement. Between Y and D the base of the 

 Fossiliferous Limestone is slickensided and grooved by being 



* I have lately observed evidence of horizontal movement in the Coal 

 Measures exposed in the river bank opposite to Claxheugh. 



t Further details can be seen in the photographs and section given in 

 my former paper in these Transactions, 1903. 



