CONSISTENCY OF GEOLOGY WITH SACRED HISTORY. 421 



the line of fracture.* We should doubtless err in assigning all these 

 mutations to one and the same period ; the phenomena are extremely 

 complicated, and an appearance which may seem to have been pro- 

 duced at the same time, and by a single operation, may have been the 

 result of many and varied changes. There is, however, one fact res- 

 pecting which there can be no hesitation, namely, that the disturbing 

 forces which have broken up the tertiary deposits came into action 

 after the elephant epoch. These elevatory movements and convul- 

 sions were manifestly of great intensity, and materially changed the 

 physical geography of the south-east of England, and the contiguous 

 parts of the continent, and occasioned the vertical position of the 

 strata in the Isle of "Wight and Hampshire. These alterations in the 

 surface of the country, must, too, have been attended with great 

 changes in the hydrography of Hampshire, Surrey, Kent, and Sussex; 

 the waters resulting from the drainage of the land, and v/hich, before 

 the existence of the transverse fractures, probably flowed through the 

 longitudinal valleys towards the east, would be thrown into different 

 channels, and find their way to the ocean by the existing river courses. 

 Traces of these revolutions remain in the boulders and superficial 

 loam and gravel, which occupy the valleys and low elevations of the 

 south-east of England. 



Subsequently to these last mentioned changes, the surface of the 

 country appears to have undergone no material alteration ; the ordi- 

 nary effects of the atmosphere, the degradation of the shores by the 

 action of the sea, the erosion by river currents of the strata over 

 which they flow, and the formation of deltas, and the silting up of 

 valleys, being the only physical changes that have taken place in the 

 south-east of England during the modern epoch, and which are still 

 in active operation. 



The existiRg rivers in this district are producing on a small scale 

 the same effects as the mighty river of the Iguanodon period ; bring- 

 ing down from the interior the debris of the strata over which they 

 flow, mixed with the bones of animals, and the trunks, branches, and 

 leaves of vegetables, and imbedding a portion in the chalk valleys, in 

 a deposit of mud or silt, and transporting the remainder to form del- 

 tas at their entrance into the ocean. 



The levels near Lewes, described in a former part of this volume, 

 afford so interesting an illustration of the silting up of the disrupted 

 valleys of the chalk, during a comparatively very recent period, that 

 we subjoin the following summary of the sequence of events which 

 they record.! First, there was a salt-water estuary peopled for many 

 years by marine testacea identical with existing species, and into which 

 some of the large cetacea, as the sea-unicorn and porpoise, occasion- 

 ally entered. Secondly, the inlet grew more shallow, and the water 



* Mr. Woodward arrives at the same conclusion from an examination of the 

 chalk valleys of Norfolk. "These," he observes, "are valleys of disruption; 

 that is, they were formed by the elevation of the chalk and its consequent frac- 

 ture, as is evident from the strata of chalk and flints on each side of the valley 

 being now found to decline from the line of elevation." — Correspondence loith the 

 Author. 



t Principles of Geology, vol. ii. p. 276. 



