FURTHER STUDIES AT VERO, FLORIDA 



669 



sion of the sands into sandstone may well have been considerable, 

 though it cannot be definitely measured. 



6. But, whatever the length of this period, it is important to 

 observe that the filling of the channel of the creek did not begin until 

 after the sand had been converted into black sandstone, for water- worn 

 pebbles of this black sandstone are abundant in the basal portion of 



:£ sjiil§ijil 



Fig. 1. — The present channel of Van Valkenburg's Creek, dry since the con- 

 struction of the drainage canal in 1913. Shows the relatively slight depth of the 

 channel. 



the channel fill. They are in fact rather more conspicuous at the 

 base of the fill than at higher levels, although occurring throughout. 

 The special significance of these black pebbles, as brought out in 

 the symposium, lies in the fact that they fix the date of the filling 

 of the channel with respect to the old bog area to the west. The 

 oldest fill in the creek channel is notably younger than the bog 

 deposits of the uplands back of the main beach ridge. 



7. The filling of the creek channel from this beginning up to the 

 present has taken place in two stages, which appear to be quite 



