Geology 



we descended, to encounter, at a depth of 30 feet, a 

 floor of basalt, the upper part of the shaft being in 

 the brown clay, with a thin bed of rolled flints at its 

 junction with the basalt. On returning to the surface 

 we found that the heap of clay thrown out from the 

 shaft had been disintegrated by the weather, and that it 

 contained numerous fossils similar to those which occur 

 in the lower subdivisions of the Eocene Series, and we 

 therefore concluded that there was here an unconformity 

 between the Eocene and the Chalk below, and interpreted 

 an east and west section through C as follows (Fig. 14). 



This gave us 

 a date for the 

 formation of 

 thedyke, which 

 was evidently 

 subsequent to 

 the formation 

 through which 

 it cut, and 

 which was altered by it (see p. 82), but prior to 

 the formation of the Eocene, which rested upon its 

 denuded surface. This latter view was confirmed by 

 the occurrence of a few pebbles of the basalt amongst 

 the rolled flints at the base of the Eocene in another 

 section close by. 



On returning to the stream and again examining 

 the brown clay in its banks, a few fragmentary fossils 

 were unearthed, and these were found to belong to the 

 same Eocene genera as those near the dyke. 



Returning to the fork we rejoined our boats and 

 proceeded up the main branch of the East River as far 



104 



FIG. 14. Section at C in Fig. 13. a, a, Eocene 

 b, Chalk ; c, Basalt. 



