348 Wood — Structure of Valleys in Essex. 



on tlie coast lines, and acts with, indiscriminating destruction, 

 breaking up, and more or less ruining, tlie old land contours ; but 

 subaerial and river action have always returned to the rescue, healing 

 with delicate symmetry the disorder caused by marine denudation, 

 remodelling and cleaning out the lost river channels, and reconnecting, 

 into watershed and valley systems, the often submerged land surface. 



III. — On the Stetjcture of the Valleys of the Blackwater 

 AND THE Crouch, and of the East Essex G-ravel, and on 

 THE Relation of this Gravel to the Denudation of 

 THE Weald. ^ 



By Searles V. Wood, Jun., F.G.S. 

 ("With a Folding Map and Sections). 



IN a paper in this Magazine, upon the structure of the Thames 

 Valley, I endeavoured to show that instead of being, as had 

 been asserted, a valley of similar structure to those of the Somme and 

 Seine, and containing deposits of nearly similar order and age, 

 the valley in which the Thames gravel was deposited possessed no 

 outlet to what is now the North Sea, being divided from it by a range 

 of high gravelless country ; and that, in lieu of such, an outlet, the 

 valley opened, in more than one part, over what is now the bare 

 Chalk country forming the northern boundary of the Valley of 

 the Weald. I also endeavoured to show that all the deposits of the 

 Thames Valley, except the peat and marsh clay, belonged to several 

 successive stages, marking the gradual denudation of the Boulder- 

 clay, the lower Bagshot, the London Clay, and the subjacent Tertiaries, 

 which had, at the end of the G-lacial period, spread over the south- 

 east of England in a complete order of succession : the sea into 

 which this valley discharged occupying, what is now, the Chalk 

 country of the Counties of Kent, Surrey, Sussex, and Hampshire, 

 inclusive of the interval subsequently scooped out to form the Valley 

 of the Weald : so that, not only was the latter valley newer than 

 that of the Thames, and of the most recent of the Thames Valley 

 deposits, except the peat and marsh, clay, but that these deposits in 

 themselves marked a long descent in time from that comparatively 

 remote period of the Boulder-clay. 



In a problem of this sort, the whole of the phenomena in the 

 region affected by it should be in imison in order to render the 

 evidence satisfactory, and the object of this paper is to show, as 

 briefly as the multifarious nature of the evidence renders possible, 

 that such is the case. 



The East Essex gravel (which I so call from its principal develop- 

 ment being in the east of Essex, although the southern extremity of 

 it lies in Kent, fringing the Medway between the Nore and Rochester), 



* This paper is intended as a continuation of that " On the Structure of the Thames 

 Valley, and its contained Deposits," at pages 57 and 99, of Vol. III. of this Magazine, 

 and the direction of sections 1,3,4, 5, and 6, given in that paper, have been shown by 

 lines with corresponding numbers on the Map accompanying this paper. 



