212 ME. C. T. TRECHMANN ON A MASS OF ANHYDRITE [June I913, 



(7) Hart Quarries. 



Nearly 2 miles to the west of the -waterworks at West Hartle- 

 pool, the land rises rather rapidly to the 200-foot contour-line 

 which corresponds with an outcrop of limestone. It probably 

 owes its presence here to a fault which cannot, however, be 

 definitely located. 



The limestone is well exposed in three quarries on the west side 

 of the road from Hart to "West Hartlepool, in a quarry at Hart 

 Windmill, and in a large quarry near Naiseberry, south-west of 

 High Throston, about a mile from the AYard-Jackson Park at 

 West Hartlepool. 



As the last-named section is the most typical, and the only one 

 where any traces of fossils seem to have been preserved, it is 

 here described : — 



Thickness in feet. Fauna. 



' Very hard, dense., brown and ashen ~) 

 grey, segregated limestones. 



Irregularly bedded, but stratifi- I „- -v -i i vj. <. i 

 cation very apparent, brecciated f 2 ° F ° SSllS oMlterated - 

 (?) in places. Powdeiy constituent j 



Highest •{ entirely removed. J 



Limestones. 'Roestone' in part of section. 6 No fossils. 



Extremely soft and friable, \vell-~~) 



bedded yellow limestones, show- { „ C Schizodus sp. 

 ing ' roestone ' structure in | \ Mytilus sp. 

 l_ places. J 



Fossils found in these beds were in the last stages of oblitera- 

 tion. The genera are recognizable,' but specific determination is 

 hardly possible. They would seem to justify the reference of the 

 beds in all these quarries to the Uppermost Limestones, here 

 protected from denudation by the overlying mass of segregated 

 calcareous material. 



Similarly altered beds occupy a very considerable area of country 

 on the west. The surface- contour of these beds is extremely 

 variable, determined no doubt by the different hardness of the 

 calcareous and magnesian portions of the rock. 



Such rocks are exposed in quarries at Wellfield, Wingate, Trim- 

 don, Haswell, etc., where in most cases they can be shown on 

 palseontological evidence to represent the western equivalent of 

 the Shell-Limestones. 



A somewhat similar limestone is exposed in a quarry at Whelly 

 Hill, near the intersection of the Durham, Hartlepool, and Stockton 

 roads. It lies very slightly above the 400-foot contour : — 



Thickness in feet. Fauna. 

 'Collapsed, recemented calcareous fragments \ , 



forming a rather massive bed ) 



Very thinly - bedded limestones, white and^| 

 (?) yellow, showdng great internal bending; 

 rMiDDLE <{ towards the base the rock becomes spongy | 

 Limestone. and associated with powdery material. J>30 No fossils. 

 Hollow spaces left by sulphates are very 

 | numerous, causing the collapse and breccia- | 

 t_ tion of the overlying part J 



