186 



thin out or graduate into the dark clay that elsewhere lies 

 above it. 



On the top of the uppermost bed of sand above described, but 

 somewhat nearer South Amboy than the commencement of the 

 dark astringent clay, there is a yellow and much coarser sand, 

 extending up to the soil. In this place its total thickness above 

 the white clay is twenty feet. The materials of this uppermost 

 layer are sometimes as coarse as gravel ; and it seems to belong 

 to the superficial diluvium, as it has an irregular undulating out- 

 line which strongly contrast with the nearly straight surfaces of 

 the beds beneath. A similar exhibition of the diluvial sand and 

 gravel reposing upon the other sands and the dark clay here 

 described, may be witnessed at various places upon the Camden 

 and Amboy railroad, and also conspicuously in the banks at 

 White Hill, where the line separating the two deposits is very 

 distinct. It is undulating, as if the original surface of the lower 

 bed had been scooped by the currents that carried along the 

 sand and gravel now forming the upper or diluvial stratum. 



Analysis- 



Potters' Clay, Morgan's Bank, South Amhoy. 



Description. — Mottled white and red throughout the mass, but 



more particularly on the surface; highly gritty between the 



teeth ; by calcination at a full red heat becomes of a brick red 



colour. 



In 100 parts it contains: 



Silica, ... - 67-6 

 Alumina, . - . 15-8 



Peroxide of iron, - - 5-6 



Water, .... 9-3 



Loss, - - - 1-7 



1000 



SECTION II. 



Greensand Formation — " MarV 



Geographical Range. — The second division of the upper 

 secondary series, which, in allusion to its peculiar composition, 



