346 SPECIAL GEOLOGY. 



various districts have been won from the deep. History 

 and tradition record the fact that the sea once extended to 

 Norwich, on an arm of which, it is recorded in Saxon manu- 

 scripts to have been situated ; while ancient cliffs existing far 

 inland, prove that the sea has receded still more considerably 

 from its ancient limits. Extensive devastation is observed 

 along the coast of Essex, which is largely composed of strata 

 appertaining to the London clay formation. The town of 

 Harwich, stated to be the representative of a more ancient 

 submerged town, called Orwell, is in inevitable danger of 

 sharing the fate of its predecessor. The coasts which sur- 

 round the estuary of the Thames present examples of the 

 countervailing destruction and restoration of the land. While 

 the cliffs of the Isle of Sheppey, which consist solely of 

 London clay, are constantly wearing away, the channel which 

 separated the Isle of Thanet from the mainland of Kent, 

 has shoaled up and formed new land. The G-oodwin sands 

 are said to have constituted the estates of Earl Goodwin, 

 which were submerged beneath the waves. Pursuing the 

 inquiry along the coast of Kent, we find the work of devas- 

 tation still in progress. The firmer cliffs of the chalk are 

 undermined and destroyed as surely as the more yielding 

 strata of the London clay. The cliffs of Dover are thus 

 sapped, and considerable falls constantly occur. At Polk- 

 stone, the same accidents are produced in a manner analo- 

 gous to that which takes place at the south side of the Isle 

 of Wight, in strata of the same geological formation, and 

 which have given rise to the celebrated Undercliff of that 

 island. The chalk at Eolkstone rests inclined on the gault, 

 or blue clay. The water which passes through the porous 

 strata so moistens the clay, as to occasion the overlying mass 

 to slide down the inclined plane formed by the subjacent de- 

 posit, and thus to produce falls of enormous extent. The sand 

 cliffs of Hastings have suffered considerable destruction. The 

 chalk cliffs of Beachy Head have undergone like abrasion and 

 disintegration. An enormous mass of rock, three hundred feet 

 in length, and thirty in breadth, was precipitated some thirty 

 years ago, and similar falls have since repeatedly occurred. 

 At Brighton, part, though not the whole, of the ancient town 

 was situated, in the reign of Elizabeth, under the cliffs, on 

 the spot where the chain-pier now extends into the sea ; 



