The River Port Hutton to Smithford 



as the depth of water would allow. Arrived at a point 

 which should, in our opinion, lie on the line of the Black 

 Point dyke, we pitched our camp by the side of the 

 stream as, no horses being here available, we should 

 have to make our exploration on foot, which might 

 take us several days. After a day's march through the 

 forest, over slightly rising ground, we again saw rolling 

 hills before us, and on reaching these, found them to 

 consist of chalk, as on the other side of the valley, but 

 now dipping to the south at an angle of 5. We were 

 not long in picking up the line of the dyke, as it here 



FIG. 15. Section across the valley of East River. 

 a, Eocene ; b, Chalk. 



formed a conspicuous feature in the landscape, standing 

 up as a wall some 25 feet high. 



Brown clay in horizontal layers was seen in a small 

 excavation, for here, too, a search had been made for 

 minerals along the sides of the dyke, and a few Eocene 

 fossils occurred. 



Our interpretation of the structure of the East River 

 Valley to the west of the dyke is indicated in Fig. 1 5. 



A valley originally excavated in the chalk, which 

 had been previously folded into a gentle syncline, was 

 filled with the deposits of the Eocene sea. These 

 deposits, much softer than the neighbouring chalk, were 

 then brought once more above the level of the sea, and 



105 



