170 DESCRIPTION OF THE STRATA. 



exposed on the weathered surface of the rock, they present the 

 appearance of the sunflower, having a circular disk in the centre, 

 ■with a margin of petals diverging from it all around. 



Even in the Hartlepool rocks, the limestone exhibits consider- 

 able diversity of structure and other qualities. In some places, it is 

 decidedly oolitic, resembling the finer varieties of the oolite ; in 

 others, it is earthy : in some, it is soft, marly, and friable ; in others, 

 it is hard and compact. Some specimens contain quantities of loose 

 marl, lodged in numerous minute pores or cavities ; others abound 

 with small holes or pores, which are empty. Most of the rock is of 

 a dull yellow or buff colour; some part is of a dull grey ; while a 

 considerable part is white, approaching to the colour of chalk, which 

 it also resembles in many of its other qualities. Indeed, the Hartle- 

 pool cliffs, though much lower than the chalk cliffs of Flamborough, 

 bear a considerable resemblance to them ; being parted by vertical 

 fissures, into which the sea rushes violently, and forms a variety of 

 caves and grottos, often supported by massy pillars. Several detach- 

 ed rocks stand in the sea, at a short distance from the front of the 

 cliffs, and of the same height ; and as the waves have hollowed out 

 their bases into numerous arches, they present the romantic appear- 

 ance of the ruins of an aqueduct, supported by huge pillars. The 

 general dip of the rock is towards the south. 



The magnesian limestone of Hartlepool does not abound with 

 organic remains ; yet a few shells may be found in almost all the 

 varieties of the rock, and in some spots, especially in the white strata, 

 the number is not inconsiderable.* 



* For a further account of the Magnesian Limestone, and the strata that succeed it in 

 Durham and Northumberland, see Mr. Winch's Paper on the Geology of these Counties, in the 

 Geological Transactions, Vol. IV. — Mr. Winch is mistaken in asserting (p. 7), that the white 

 oolitic limestone of Hartlepool "contains no shells or marine exuvi* :" the authors found in it 

 both univalves and bivalves, especially the latter. 



