APPENDIX E. 



EXPLANATION OP MAPS. 



Five maps, Plates X, Xa, XI, XII, XIII, accompany this report, 

 in the envelope attached to the cover. 



Plate X. — This map shows the distribution of the principal 

 clay-bearing formations in the State, as explained by the legend. 



North of the terminal moraine, and also within the basin of the 

 extinct Lake Passaic there are considerable areas of clay of glacial 

 derivation which are of value for common brick. They do not, 

 however, occur over all this area, but, on the contrary, are found 

 in more or less widely separated localities. 



The Raritan belt of sand and clay ( light-green horizontal lines, 

 K r, ) extends from Woodbridge, Middlesex county, to Lower 

 Penns Neck, in Salem county. Since thick beds of sand occur in 

 this formation, the clay beds occur on the surface over only a part 

 of the area thus marked. Since, moreover, beds of sand and 

 gravel of much later age (Pleistocene) in places cover the Raritan 

 and other formations quite deeply, the area within which these 

 clays can be mined is still further circumscribed. Prospecting for 

 the Raritan clays should not extend beyond the area indicated 

 by this pattern on the map, although it is certain that they do not 

 occur within workable depths at all points within these limits. 



The two clay deposits, known as Clay Marl I and II, are here 

 indicated by one color and pattern (dark-green, vertical lines, 

 K c m). Clay Marl I occurs along the northwestern part of the 

 belt, Clay Marl II along the southeastern. These brick clays occur 

 everywhere along the belt thus mapped, but locally they are deeply 

 buried by the later gravels, and therefore are not exposed. 



The area of Miocene and Pliocene sands and clays is much 

 larger than the others. The surface is chiefly sand, and over much 

 of the region there is no evidence of clay. Nevertheless, lenses 

 of valuable buff- and red-burning clays frequently occur, the 

 presence of which can usually be detected only by boring. Under 

 these circumstances it has not been practicable to attempt their 

 actual delimitation. 



(530 



