158 The Petrography and Genesis of Sediments 



(2) The lack of rounding of the sand. 



(3) The very small proportion of heavy minerals. 



(4) The relative abundance of magnetite and garnet in the heavy 

 portions, a character which seems to be correlated with coarseness and 

 poor sorting. 



(5) The scarcity of mica. 



(G) The reworked glauconite. 



(7) The freshness of the feldspars. 



This bed differs markedly from most occurrences of Matawan mainly 

 in the coarseness of its grain, and in the absence of black clay. It occurs 

 in the following section as recorded in the field, beginning at the top : 



5. Monmouth glauconite sand penetrated by limonitic crusts. 



4. A marked J inch limonitic crust separating 5 from 



3. A sandy transition zone (sample 10) to 



2. Argillaceous Matawan with finely disseminated limonitic crusts. 



1. Fresh argillaceous Matawan. 



In the absence of analyses of the underlying and overlying beds this 

 sample loses much of its significance, yet the field relations, and general 

 knowledge of the two formations between which it lies, in conjunction with 

 its own analysis, seem to point pretty clearly to its interpretation. The 

 author is then inclined to regard it rather as a basal part of the Monmouth 

 reworked from the underlying Matawan than as upper Matawan. The 

 general coarseness of the material (which is of the character of a basal 

 bed), the reworked condition of the glauconite, and the weathered condi- 

 tion of the upper part of the Matawan, as shown by the limonite crusts in 

 bed 2, support this view. The distinction is rather essential. If the bed 

 belonged to the Matawan it would represent a gradual shallowing, form- 

 ing a transition to the coarser sediments of the Monmouth. By the other 

 interpretation there was an interval after Matawan time during which 

 the upper part of the Matawan was weathered, then a transgression of the 

 Monmouth which accumulated a basal layer of coarse material and 

 reworked glauconite before the typical Monmouth conditions with the 

 formation of primary glauconite were reached. 



