Maryland Geological Survey 141 



IV. Clay 

 A normal, pure-looking, blue-gray clay showing under the microscope few mineral 

 grains, hut also few of the polarizing fibrous particles which appear to be characteristic 

 of most of the clays ; it is mainly amorphous brown matter. 



Summary and Conclusions. — This is a typical, normal sample of the 

 Matawan of this region and as such offers little requiring special com- 

 ment here. The condition of the glauconite in it seems to prove that the 

 glauconite is primary, so that this sediment represents lithologic condi- 

 tions under which glauconite may be formed. There has been very little 

 secondary action of any kind as is proved by the absence of limonitic and 

 of glauconitic staining, while the sharpness with which the separation of 

 clay and sand could be made confirms this conclusion. 



The seeming argillaceous concretions (see coarse and medium-grained 

 sand) should be noted. Noteworthy, also, is the small amount of carbon- 

 aceous matter. 



SAMPLES NOS. 3, 4, 5, AND 6 



General Summary and Conclusions. — These four samples are from one 

 locality and section and were taken in order to find what the analyses 

 might show to supplement their field relations. The results are inter- 

 esting enough to justify a special discussion here. 



Following is the field section, beginning at the top : 



Feet. 

 (5) A capping of post-Cretaceous gravel and diagonally (current) 



bedded sand. 



(4) Very glauconitic, yellow, somewhat argillaceous sand 2-3 



Sharp contact with 



(3) Very glauconitic, gray, argillaceous sand (Sample 6) 6 



Bed 3 seems to grade into bed 2 although an appearance of a 

 sharp contact is given by a thin line of limonitic staining separat- 

 ing the two beds. 

 (2) A light yellow, glauconitic sand containing little clay in the upper 

 part but growing more argillaceous and gray towards the bot- 

 tom (Sample 5) 12 



About 2 feet at the top are filled with tubes % inch in diameter, 

 running through the sand in all directions and containing very 

 glauconitic sand. 

 Sharp contact with 

 (1) A dark gray, micaceous, glauconitic, argillaceous sand, growing 

 less micaceous and more glauconitic towards the lower part. Ex- 

 posed to base of section 5 



(Sample 4 = upper micaceous part.) 

 (Sample 3 = lower glauconitic part.) 

 10 



