AT CI.AXnKIKiH AND DOWN 1111,1,, CO. DURHAM. l6l 



forced along the Lower Limestone. In the unbedded lime- 

 stone a series of horizontal division planes have been 

 produced, dividing this bed into a nuinber of lens-shaped 

 masses. From exposures of the Lower Limestone in the 

 immediate neighbourhood many feet of this rock may have 

 been thrust out of tlie western part of the section, and from a 

 study of the fossils Dr. Trechmann thinks part of the 

 Fossiliferous Limestone is missing. Unfortunately at the 

 present time owing to the landslip which occurred in 1905*, 

 some of the features described cannot now be so clearly seen 

 as when I first described this section. In the old quarries in 

 the Claxheugh district there are good exposures of the Lower 

 Limestone, of minutely faulted beds, of breccias, and of a 

 very fossiliferous portion of the Reef, from which a collection 

 of Magnesian Limestone fossils can be made. 



Several quarries have been worked on Down Hill, and this 

 area affording evidence similar to Claxheugh is worthy of a 

 short description. It is only by comparison with the features 

 cf the latter and other exposures that the details of the 

 sections on the flanks of these hills can be understood. The 

 detailed section given is of two quarries on the western face of 

 the Permian escarpment near Down Hill House. The principal 

 feature to which I wish to refer is that in the sand pit a small 

 triangular mass of the Marl Slate and Lower Limestone, 

 resting on the Yellow Sands is overlaid by the unbedded 

 limestone of the Reef, while in the limestone quarry some 50 

 yards away the Lower Limestone is 40 feet thick. It is 

 evident that a considerable thickness of Lower Limestone 

 has been thrust out of position in the exposure at the sand 

 pit. There is also evidence of movement' in the limestone 

 quarry in the Assuring of the Lower Limestone and in the 

 disturbance of the upper beds of that division. Near Hylton 

 Castle on the south side of the hill about one mile away 

 highly tilted and displaced beds of Lower Limestone occur, 

 from a study of which it is possible to understand the way in 



* Described in these Transactions, New Series, Vol. i, Part 3. 



K 



