70 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Juiie 13, 



The Englisli Channel occnpies a Taller bounded by two parallel 

 systems of eleyation. The hne of 49° dS', commencing from the east 

 coast of France, near Dieppe, and which passes a httle south of the 

 Lizard Point, is as long a straight line as can be drawn within it. A 

 physical area may haye a general form and outline, which may not at 

 all represent the direction of the forces by which it has been produced. 

 The moyements by which relief has been giyen to portions of the 

 earth's crust are seldom continuously linear; the lines themselyes, 

 taken separately, are constantly seen to diminish in amount in oppo- 

 site directions, and to be arranged en echellon. Such is the case along 

 the South of England ; the accidents of the sti'ata nin east and west ; 

 such is also the case in Lower Xonnandy and Brittany ; this is their 

 true direction as areas of eleyation, of which the Channel is the inter- 

 yening depression : a central line along this area would haye a general 

 dii'ection from E.X.E. to W.S.AY. : in this instance therefore the 

 geological and geographical features are not parallel. Like instances 

 may be traced whereyer long lines of eleyation haye been produced. 

 A central hne from the Straits of Doyer across the Gemian and North 

 Seas would equally mislead us there ; the true physical featm-es of 

 that depression are the straight north and south line of coast along 

 the departments of the Somme and the Pas de Calais, the rocky- 

 masses of the Yame and the Ridge rising with steep sides from deep 

 water ; the same hne, if prolonged, will pass in front of the Goodwin 

 Sand, along a trough having in places a depth of foiiy fathoms, and 

 will define the coast of England from Orford Ness to Yannouth. 

 The direction of the troughs haying thirty fathoms water are also 

 paraUel with this line. 



A series of transverse sections from the coast of England to that of 

 France, di'awn north and south, will show that the Channel area is 

 one of depression. In all such sections the sedimentary sti-ata on 

 either side have an inward dip. This position of all the secondar}' 

 beds is famihar to most geologists, and hardly requh'es illustration. 

 The east and west strike of the older strata to the west of the secon- 

 daiy fonnations is indicated on the map, and the hke direction ob- 

 tains throughout the palaeozoic groups of Brittany and Lower Nor- 

 mandy. The lower yalley of the Seine may probably be connected 

 with the later distm'bances of the Channel yalley ; the lines of deepest 

 water are along its south side, and will be shown to correspond with 

 its original greatest depression : it is a common character of linear 

 undidations of the earth's crust, that they break into fractures or 

 faults at their extremities. The general direction of the yalley of 

 the Seine from Havre to Rouen is due east and west. The re- 

 markable cliffs which occur at places along this valley have been 

 described by Sir C. Lyell ; they can hardly have been produced by 

 the present river, nor is there any accumulation of shingle along its 

 course to account for its occupation by the sea. The features are 

 difficult of explanation, but it suggested itself to me when I last saw 

 them, that they were the result of a fault traversing a mass of ele- 

 vated strata, by which portions had been let down ; a depression of 

 the strata on one side corresponchng with the vertical wall of the cliff 



