The River Port Hutton to Smithford 



A day's journey brought us to what we believed 

 should be the line of the great Black Point dyke. 

 About this point the alluvial flat came to an end, and 

 the stream flowed in a V-shaped valley cut in a brown 

 clay which was well exposed at frequent intervals. No 

 signs of the dyke or of the chalk were to be seen, 

 however ; furthermore, pebbles of basalt and flint were 

 absent from the bed of the stream. 



Through a clearing away to the right we could see 

 that the land rose more rapidly, and on the slope of the 

 hills we found some pebbles of basalt ; a little farther up 

 we came upon the 

 heading of a de- 

 serted mine which 

 had been driven 

 into the hillside in 

 search of metallic 

 ores. Judging from 

 the materials of the 



tip-heap, the search FlG ^^ rf M workings 



had proved fruitless, 

 but other similar excavations in the immediate neighbour- 

 hood gave us the key to the geological structure. 

 These were in the relative positions indicated by 

 A B and C in Fig. 13. A was a heading driven 

 along the side of the basalt dyke, and one side of 

 it was in chalk ; B was a small pit some 10 feet 

 deep, cut in the chalk but showing the basalt in its 

 western wall, and a thin layer of brown clay capping 

 the section on its northern side. The clay was seen to 

 overlie both the chalk and the basalt in this section. 

 At C there was a shaft which with some difficulty 



103 



