1849.] AtJSTEN ON THE VALLEY OF THE ENGLISH CHANNEL. 87 



no accordance witli that of the north of England, — and that it crosses 

 at right angles, and cuts off ranges, which not only have been raised, 

 but were deposited long after the ' System of the North of England ' 

 rise took place. 



§ 2. Age of the Channel Valley, 



The valley of the Channel being due to depression and not to ex- 

 cavation, the geological period of such depression is another obvious 

 point of interest connected with it. 



From the parallelism of the valley of the Channel with certain lines 

 of elevation along the South of England, Sir Charles Lyell has sug- 

 gested that the movement from which this configuration resulted 

 might be referred to some portion of the eocene period : but with 

 such an abrupt termination as the Bagshot series presents, and with 

 the occurrence of the lower portions of the eocene deposits up to 

 the very edge of the chalk escarpment of the Wealden denudation, we 

 must suppose, as we do Avith respect to the secondary beds of the same 

 district, that the whole of the eocene group, as it exists in the South- 

 east of England, was originally carried continuously over the Wealden ; 

 and that the phaenomena of denudation of this district are entirely re- 

 ferable to some post-eocene date : geological features, or rather phy- 

 sical ones, may present parallelism, but these will be found to have 

 very little connexion with the question of geological age. 



The only way by which to test the relative levels which portions of 

 a country may have had at any distant time, is. by the beds which 

 occur over them. If of two areas, one presents a surface of eocene 

 strata, and the other, like eocene deposits, surmounted by distinct 

 and younger beds, of the existence of which the other area offers no 

 indications whatever, we rightly infer that these two areas had in the 

 interval assumed different relative levels. Such is the difference be- 

 tween the two valleys of the English and German Channel — the crag 

 deposits occupy both the English and Belgian sides of the German, 

 whilst they are altogether wanting in the English Channel valley. 

 Between the uppermost freshwater deposits of Hampshire and the 

 Isle of "Wight, we have no indication whatever of marine beds con- 

 taining intermediate forms between those of the eocene and present 

 seas. 



Marine beds containing existing species occur at intervals along 

 the coast-line of the English Channel : they were never probably con- 

 tinuous, and all belong to the marginal zone. The movement of the 

 materials of this zone, in the present state of the Channel, has been 

 noticed in the former part of this paper, as taking place in a direction 

 from west to east. 



In a description I gave of raised beaches at the entrance into Tor- 

 bay and at Slapton, I stated that chalk-flints, and other materials 

 from rocks to the eastward, entered into their composition, and that 

 these materials were not to be found in any of the beaches in the 

 vicinity at present. I re-examined these beds in the course of last 

 summer, and found the proportion of chalk-flint, in subangular frag- 

 ments, far greater than from recollection I had supposed it to be. It 

 must not be understood from this that chalk-flint pebbles are not to 



