4 GEOLOGY. 



The Rocks of the Newark Series. 1 



The rocks of the Newark series are of various sorts, including all 

 the common varieties of fragmental rocks, some of which are here 

 developed in unusual phases. There are abundant conglomerates 

 and some breccias, though sandstones and shales make up the prin- 

 cipal mass of the series. Locally, the system contains a little lime- 

 stone, and in Virginia and North Carolina there is bituminous coal. 

 Elsewhere the shale is sometimes carbonaceous. 



The conglomerates.— Wherever standing waters came to occupy 

 those parts of the old land surface which warping had brought low, 

 they found upon it a mantle of decomposed and partially decomposed 

 rock, out of which arose basal conglomerates, made up partly of the 

 local rock (crystalline schists), but largely of its most resistant part — 

 the material of the quartz veins which affected it. At the same time, 

 drainage from the adjacent lands doubtless contributed sediment 

 to the areas of deposition. 



The conditions for conglomerate formation were present for long 

 periods in some places, as shown by the thickness of the beds; but 

 they were present at the same place at different times, for the con- 

 glomerate is not simply basal. Thus along the northwestern border 

 of the series in New Jersey, beds of coarse conglomerate at various 

 horizons represent the shore phase of beds which grade out into sand- 

 stone, and even into shale. As now exposed, the conglomerates are 

 seen in greatest development along the eastern border of the New 

 England area, and along the western borders of the areas farther south. 



The chief constituent of the Newark conglomerate is quartz, as 

 already noted, but in places it contains much quartzite and crystalline 

 schist. Again, in some places in New York and New Jersey, as well 

 as at points farther south, the principal constituent is limestone. 

 Locally (some parts of New Jersey) so little else enters into its make-up 

 that it is quarried and burned for lime. The masses of limestone 

 involved are occasionally several feet in diameter. 



To appreciate the exceptional character of the conglomerate it 

 may be recalled that limestone, on decomposition, is mainly dis- 

 solved, the insoluble part only becoming available for sediments. 



1 The Connecticut valley and New York- Virginia areas are best known, and the 

 descriptions of the formations here given apply especially to them. 



