Maryland Geological Survey 149 



cracks of many quartz and feldspar grains in this and other samples. 

 While the botryoidal grains of glauconite were presumably formed in the 

 shells of foraniinifera, these encrustations and stains must have been 

 formed unenclosed in the midst of the sediment. Though the manner of 

 their formation is not yet clear this difference in the conditions under 

 which they developed may well account for their different appearance. 



Concerning the complex chloritic grains, also in the full-current 

 product, I have no interpretation to suggest, but merely draw attention 

 to them again here. 



SAMPLE NO. S (FIG. H, p. 169) 

 Serial number : 16. 

 Field number : 5-9-12-1911. 

 Formation : Matawan or Monmouth. 

 Locality : Camp Fox, Chesapeake and Delaware Canal. 



Appearance : Fine-grained, dark-green, speckled sand, considerably weathered and stained 

 with limonite. 



Mechanical Analysis 

 Sample 7.700 gm. 



Per cent of 

 sample 



Sands 88.8 



Silt 0.6 



Clay 11.1 



Total 100.5 



Per cent of 

 total sands 



Coarse sand 0.5 



Medium sand 27.2 



Fine sand 42.8 



Very fine sand 26.3 



Extra fine sand 2.9 



Total 99.7 



Per cent of 

 very fine sand 



Light 63.2 



Heavy 36.5 



Total 99.7 



Magnetic Separation Per cent of 



total heavies 



Attracted at 1500 ohms 90.5 



Attracted at full current 4.4 



Non-magnetic 0.2 



Magnetite 1.8 



Total 96.9 



Per cent of 

 1500-ohms 

 portion 



Attracted at 1500 ohms, S. G.> 3.002 6.2 



Attracted at 1500 ohms, S. G.<3.002 (glauconite)... 94.8 = 85.8% of heavy = 31.3% of 



very fine 



Total 101.0 



