164 DESCRIPTION OF THE STRATA. 



bundles, they are so thickly reticulated and crowded together, tliat 

 the quantity of gypsum greatly exceeds that of the clay. Where the 

 gypsum becomes plentiful, the upper part of the stratum in which it is 

 imbedded begins to wear out, its place being occupied by alluvium; 

 and the latter having been partly w ashed away by the river or the rains, 

 the bundles or masses of gypsum are laid bare to a considerable dis- 

 tance along the foot of the bank, till the strata sink down, and the 

 bank becomes wholly alluvial. 



The gypsum, in the recent fracture, resembles fine white sugar; 

 but its crystals are considerably larger, and many of them are of an 

 oblong shape and very thin. It has in most places a reddish tinge ; 

 its oblong laminated crystals, when separated, are found highly trans- 

 parent, like selenite ; and the whole vein is translucent, especially 

 near the edges. Many of the specimens are soft and friable, easily 

 crumbling between the fingers ,■ others are moderately hard and firm. 



On the opposite side of the mouth of the Tees, at Seaton near 

 Hartlepool, we find a very remarkable specimen of these strata. To 

 the south and the north of Seaton, the cliffs are alluvial ; but directly 

 opposite that village, the strata rise up in the form of a ridge or arch, 

 the highest part of which stretches out from Seaton towards the sea, 

 nearly at right angles with the shore, but rather inclining towards 

 Hartlepool ; while the strata bend down on both sides of the ridge, 

 dipping towards Hartlepool on the north, and towards Coatham on the 

 south. On the shore at Seaton, the waves have worn away the higher 

 part of the rocks, and displayed in the cliff" a beautiful section of the 

 party-coloured strata. In the middle of the arch, the upper strata 

 are gone, and are replaced by alluvium ; but we see what they have 

 been, by tracing them on both sides of the ridge. The whole series 

 may be stated as under : 



1. A bed of sandstone, 6 feet thick ; half of which is red, and 

 Ihe other half yellow, or yellowish grey. 



