142 The Petrography and Genesis of Sediments 



Considering the field section and the analyses together we find that they 

 fall very naturally into two distinct types. 



A. That represented by samples 3 and 4 = bed 1; micaceous material, 

 with reworked glauconite and much carbonaceous material. 



B. That represented by samples 5 and 6 = beds 2 and 3; typical 

 Matawan beds, with glauconite evidently formed in place. 



The resemblance of type A to the Magothy as at Betterton (see 

 samples 1 and 2) is apparent, with the marked difference, however, 

 that there is here no rapid alternation vertically in the character of the 

 beds. Without paleontological evidence it is moreover not certain that 

 bed 1 here is not Magothy, though just as there was evidently glauconite 

 formed before the formation of the similar beds of the Magothy at Better- 

 ton, so there is no apparent reason why in the midst of the glauconite 

 formation of the Matawan there should not be a facies similar to the 

 Magothy. 



While the present state of our knowledge of sediments does not allow 

 a definite classification of these beds, I think it is evident that bed 1 repre- 

 sents more of the river delta type of deposit while beds 2, 3 and 4 repre- 

 sent the more quiet conditions under which glauconite is formed. 



Considering these two groups we find at first glance a remarkable lack 

 of diil'erence in the relative proportion of sand and clay and in the per- 

 centage of very fine sand, but the striking difference is in the distribution 

 of the other sizes. Thus in what are tentatively called the delta type there 

 is very little material coarser than the very fine, this portion forming the 

 maximum and appearing in the diagrams (figs. C, D, p. 169) with the 

 abruptness characteristic of delta and stream sediments (cf. figs. D, I, J, 

 p. 170) ; at the same time the abundant extra fine gives a transition to the 

 clay — a feature which from these same diagrams on p. 170 is seen to belong 

 more to this type of sediments. 



Samples 5 and 6 (B, F, p. 169) on the other hand, while they show some 

 marked differences from each other, have in common a clear antithesis to 

 samples 3 and 4 in the two features just enumerated, that is, there is a 

 more gradual gradation through the coarser sizes to the maximum in the 



