1889.] 
387 
[Davis and Wood. 
beds appears as an essentially straight line on the peneplain of to- 
day, and hence their foundation must have been a peneplain. But it 
is very probable that the area of the Highland crystalline rocks was 
not so soon worn down ; these rocks are much harder than the shales 
and most of the sandstones of the Newark belt, and when the latter 
were reduced to their lowest topographic terms, the former may 
still have shown hills of considerable height. But the denudation 
of the Highlands continued during all the time of Cretaceous dep- 
osition, and this great interval following on the previous one ap- 
pears to have been sufficient for the production of the Schooley 
peneplain even over the area of the hard crystalline rocks. 
If the southeastern part of the Schooley peneplain were a plat- 
form of marine denudation, the lowest of the superposed beds; 
would be made of fragments derived from the closely adjacent land- 
ward part of the plain ; but numerous exposures in the clay pits 
about Amboy have demonstrated that the lowest members of the 
Cretaceous series, even where lying directly on the red shales of 
the Triassic formation, contain very few fragments of red shale, 
and are in great part derived from some other source. Its sands< 
and white quartz pebbles might certainly have come from the High- 
lands. This confirms the idea that the Highland plain was of sub- 
aerial origin. Its Atlantic shore-line must have stood southeast of 
New Brunswick and Amboy at least until the relatively soft Tri- 
assic beds were baselevelled ; then a small submergence would 
cause so rapid a transgression of the sea over the land to the north- 
westward that the shore w T aves would not remain long enough at 
any point to accomplish much work at the bottom ; after the sub- 
mergence, the shore line would probably be found west of the Tri- 
assic area on the edge of the hard crystalline rocks, whose reduction 
to baselevel was slower. The fine waste from the shore might sup- 
ply the sands and marls of the Cretaceous beds with little admixt- 
ure from the red shales on which the beds were deposited . 1 
All this accords better with the subaerial origin of the Highland 
plain, above adopted, than with its submarine origin. 
VThe absence of the fragments of shale in the Cretaceous beds is so nearly complete 
that it has been suggested that the land from which they were derived lay to the south- 
east of the present coast, and has since then sunk out of sight (Geol. N. J., Report on 
Clay Deposits, 1878,30). But the bottom clay beds do contain some fragments of red 
shale (id., 40, 41, 43, 162, 168), and the explanation given above seems to us more in ac- 
cordance with the geographic development of New Jersey and with the general geologic 
history of the Atlantic slope. 
