^^^^^ 



306 C. N. FENNER 



retreat of the waters and the baking of the mud under a hot sun. 

 That arid conditions prevailed is indicated also by the frequent 

 presence of sharply defined pieces of shale in the pebble beds. During 

 long exposure the iron-impregnated mud must have hardened to such 

 a degree as not to be ground up and destroyed by a succeeding rush of 

 torrential waters. 



THE SANDSTONES 



These are ferruginous silicarenytes — siliceous sands, colored by 

 oxide of iron. In places they form extremely massive beds in the 

 series, up to 25 or 30 feet in thickness, with hardly a Hne of parting. 

 Beds of this kind are made up of rather coarse quartz fragments, 

 rounded or subangular, mixed with a little decomposed feldspar, and 

 frequently show no hint of stratification on either fresh or weathered 

 surfaces. The finer sandstones carry much mica and are generally 



better stratified. A little cross- 

 bedding has been observed, the 

 direction of the lines differing by 

 ^'S- * a sKght angle. 



The sandstone strata may contain anywhere in their mass indi- 

 vidual pebbles or small beds of pebbles of irregular shape and extent. 

 Fig. 4 shows a characteristic pebble bed on the west side of Thomas' 

 quarry. Pebbles are up to one- 

 half inch or more in diameter. '{M^:-^''7'''r^f-::y^i^d^:i}^^ 

 Below is even-grained sandstone tS?f^*'^^|||Sp|^S;|:i^ 

 separated by a sharp Hne from the ''■'^'■^^^(^^ii-^^'IM^i'MMmi^^ 

 pebbles. Above, the gravel grades 

 into sandstone. Fig. 5 represents '^' 



the structure of a gravel bed a few hundred feet north of the D. L. & 

 W. R. R. station at Paterson. On the left side the dividing Hne 

 between gravel beds and sandstone cuts sharply downward across the 



sandstone layer. On the right 



t;;, there is a grading of pebbles into 



^ sand. A rough stratification is 



apparent in the pebbles. Fig. 6, 



/^''Y i>- from Pope's quarry, illustrates 



a somewhat different feature. The intercalated bed is here mostly 



shale, in the midst of a massive sandstone. 



