124 The Petrography and Genesis of Sediments 



The Analyses 



SAMPLE NO. 1 (FIG. A, p. 169) 

 Serial number ' : 7. 

 Field number : l 10 -10-2-1911. 

 Formation : Magothy. 

 Locality : Betterton. 



Appearance : A compact, massive, bomogeneous, slightly greenish-gray, fine-grained, 

 micaceous, argillaceous sand. 



Mechanical Analysis 

 Sample 11.040 gm. 



Per cent of 

 sample 



Sands 73.4 



Clay 26.1 



99.5 



Per cent of 

 total sands 



Coarse sand 4 



Medium sand 7.0 



Fine sand 14.4 



Very fine sand 45.3 



Extra fine sand 33.2 



Total 100.3 



Per cent of 

 very fine sand 



Light 89.3 



Heavy 10.0 



99.3 



Magnetic Separation Per cent of 



total heavies 



Attracted at 2000 ohms 43.65 



S.G.> 3.002 15% 



S. G.<3.002 (glauconite) 80.2%=32.35% of heavies 

 = 3.20% of very fine 



Attracted at full current 37.10 



S. G.<3.002 (mica) =23.45% of heavies 

 S. G. > 3.002 largely pyrite concretions 



Non-magnetic 1.70 



Magnetite 17.40 2 



99.S5 



DESCRIPTION OF PRODUCTS 



A. TJndek the Hand Lens 3 



There is very much carbonaceous plant matter which gives all the sands a dark, 

 blackish-gray appearance. 



The coarse, medium, and fine-grained sands all show a considerable proportion of well- 

 rounded and smoothed quartz grains. They are all three speckled with the argillaceous 

 grains described under the very fine light portion, the proportion of these increasing 

 in the finer portions. Smooth limonitic grains occur in all of the portions, perhaps from 

 the alteration of glauconite grains. Heavy minerals seem to be very scarce in these 

 coarser portions though mica is scattered through the " fine-grained " sands. 



1 The serial number is the number given to the analysis when it was made, indicating 

 the order in which the samples were taken up, hence not corresponding to the present 

 order which is stratigraphic. 



- High magnetite. 



3 Magnification X 10. 



