Yol. 69.] IN THE MAGNESIAS LIMESTONE AT HARTLEPOOL. 187 



at the Warren Cement-Works at Hartlepool, at a spot exactly a 

 sixth of a mile from the nearest known outcrop of Magnesian Lime- 

 stone which occurs beneath the iron railway -bridge at Throston, 

 and on the north-west or inner side of the outcrop of that rock 

 upon which Hartlepool stands. 



Tbe following section was passed through in descending order: — 



Thickness in feet inches. 



Blown sand 22 



Submerged forest- or peat-bed 8 



Feet~) 



Bed clay 18 I 



Bed clay with small stones 6 \ rl • , -, 



Dark clay and stones 39 J- racial L 67 



Bed clay 2 | de P oslts ' > 



"Soft limestone (or boulder)' 1 I 



Red clay 1 J 



Gypsum 1 5 



Anhydrite 265 7 



Dark-grey limestone passing into a broken ^ 38 



limestone with abundance of water. ) " 



The solid rock was met with at a depth of 97 feet, and consisted 

 of gypsum, passing after a farther depth of 17 inches into a bed of 

 pure anhydrite of the unusual thickness of 265 feet 7 inches. 



The anhydrite was more or less streaked and banded with 

 Magnesian Limestone in its lower part, the bands of limestone 

 occurring in irregular horizontal fragments and layers, which become 

 larger and more numerous towards the base. The anhydrite was 

 again partly altered to gypsum at the base of the mass, and passed 

 quite conformably down into a bed of very hard dark-grey Mag- 

 nesian Limestone, which was met with at a depth of 364 feet and 

 pierced to a depth of 38 feet, when a bed of broken rock was met 

 with and a good feed of water was obtained ; this water proved to be 

 highly charged with solids, chiefly chlorides and sulphates. 



I recently undertook a detailed examination of the cores of the 

 boring which are still preserved, with the view of determining, if 

 possible, the exact horizon of this limestone, its composition, and 

 the nature of its residues. Although the rock had long been 

 supposed to be unfossiliferous, by carefully breaking it up three 

 recognizable species of fossils were obtained. 



The cores of the limestone are now very much mixed up, DUt in 

 the 38 feet of gypsiferous rock underlying the anhydrite-bed at 

 least three varieties are met with, as follows (in their apparent 

 order of superposition) : — 



A. Limestone interbedded with anhydrite to- "^ 



wards the lower margin of the anhydrite- j 



bed. A hard, compact, dense, dark-grey j> No fossils. 



rock, containing much anhydrite but no | 



gypsum. J 



B. Immediately underlying the anhydrite-bed. "^ 



A very hard, dark-grey, dense, fine-grained 



limestone having fissures and cracks filled I -^ f oss ii s 



with gypsum. The rock is brecciated in f 



part, the broken fragments being re- j 



cemented with gypsum. J 



