W. M. Fontaine—Mesozoie Strata of Virginia. 231. 
deposition of this material. The distinctness is so great that at 
the line of junction of the two, the grains of the grit may be 
pores out separately from the clay. This clay sometimes, 
owever, is interstratified for some distance with the sandy 
matter, the layers of sandy grit and clay alternating but not pass- 
ing into each other. The clay is most commonly bluish or grayish 
in color, less commonly, pale reddish or liver-colored. It is very 
fine grained, highly plastic and tenacious, and thus contrasts 
strongly with the matter in which it is imbedded. The layers 
are rarely over a foot thick, and sometimes occur at short 
intervals apart, separated by the pebbly grit. 
sh the curious features of inclining at various angles 
es : 
nest of stones. In one place I saw three such short layers 
diverging from one extremity (where, however, they were not 
united) like the fingers of a hand, and ending abruptly in the 
normal pebbly grit. They do not usually extend horizontally 
more than twenty or thirty feet. Ao 
With these clay seams we often find rolled masses of similar 
matter, which sometimes have the diameter of four or five feet: 
time. This clay is of special importance as it contains the 
Am. Jour. Sct.—Turrp Sertes, Vou. XVII.—No, 99, Marcu, ‘ 
16 
