Maryland Geological Survey 137 



fine-grained portions with which it goes in sedimentation, and the low 

 proportion of heavy minerals, yet without a very high percentage of clay. 



(2) The second important feature is the apparent secondary character 

 of the glauconite. There are no botryoidal grains, all those that occur 

 being rounded, and occurring only in the very fine-grained and finer 

 portions. 



Furthermore there is to be noted : 



(3) The abundance of carbonaceous matter. 



(4) The weathered condition of the feldspars. 



(5) The abundance of biotite. 



Of great general interest as bearing on the problem of the origin of 

 glauconite are the rounded grains of substance having the appearance of 

 clay and yet polarizing, suggesting a transition form between clay and 

 glauconite. I shall take these up later in a general discussion of the 

 glauconite below. ( See p. 176, below) . 



SAMPLE NO. 5 (FIG. E, p. 169) 

 Serial number : 11. 

 Field number : 1-7-13-1911. 

 Formation : Matawan. 

 Locality : Chesapeake and Delaware Canal. 

 Appearance : Yellow, micaceous and slightly glauconitic sand. 



Mechanical Analysis 

 Sample S.395 gm. 



Per cent of 

 sample 



Sands > 92.fi 



" Clay " (mainly yellow ocher) 7.7 



Total 100.3 



Per cent of 

 total sands 



Coarse sand 0.2 



Medium sand 2.S 



Fine sand 24.9 



Very fine sand 69.0 



Extra fine sand 3.1 



Total 100.0 ' 



Per cent of 

 very find sand 



Light 90.4 



Heavy S.6 



Total 99.0 



1 Total sands by summation of parts. 



