Northumberland and Durham. 9 



direction. It appears therefore that their dip is not affected by the 

 limestone. It is a circumstance however too well ascertained to 

 admit of a doubt, though difficult to be accounted for, that the coal 

 is deteriorated in quality where covered by the limestone. 



Galena is the only metallic ore that I have observed in this lime- 

 stone. It has been found in small strings at Whitby quarry, 

 Clacks-heugh Blackhall-rocks, Ryehope, and amongst the rocks 

 below Tynemouth castle : at the latter place calcareous spar is the 

 matrix. 



The crystallized fossils are small crystals of calcareous spar, formed 

 in groups of acute three-sided pyramids ; sometimes white and 

 opaque; at other times yellowish or hair brown and translucent, 

 lining cavities of buff marly limestone ; from the cliffs near South 

 Shields and Marsden. 



Botryoidal masses of fetid limestone devoid of magnesia, in balls 

 varying from the size of a pea to two feet in diameter, imbedded in 

 soft, marly, magnesian limestone, are found at Hartlepool, in the 

 quarry at Building hill, near Sunderland, and on the sea-coast a mile 

 or two north of Monk Wearmouth. These balls are radiated from 

 the center, their colour hair brown, fracture shining, cross fracture 

 splendent approaching to vitreous : white calcareous spar is frequently 

 observed within them. See Sowerby, Brit. Min. tab. 38. 



Stalactitical fetid limestone. See Sowerby, tab. 148. These 

 cellular masses resemble corallines, and are also met with in the 

 marly limestone above described. 



Organic remains are rarely met with in this limestone. The most 

 remarkable one was found in a quarry at Low Pallion. It is the im- 

 pression of a fish,* which appears to belong to the genus Chsetodon. 



* See Plate 2. 



Vol. iv. b 



