Boroughs Brooklyn and Queens Geology | Gratacap: Geology of New York City Page 188



	BROOKLYN AND QUEENS 157

	beds were removed; the harder, more resistant, remained. These latter began the establishment of a hill series through New Jersey (Perrineville, Monmouth County), with an accompanying valley, the Hightstown Valley, and extending northeasterly in Long Island in the Mannetto Hills, and its reciprocal depression, Long Island Sound—or valley. The rivers issuing from the higher inland country traversed the valleys and the hills, through the transverse depressions, and reached the ocean almost in a direct line (Fig. 36). Then followed a later pliocene (Lafayette) submergence and the deposition of new sediments. The narrow transverse depressions were filled up, the deeper valley northwest or west of the lineal hill ridge was not, and with re-elevation the former outward flowing rivers would be deflected into this trough, failing to recover their ancient channels that crossed the coastal plain to the ocean. In this way the littoral rivers would have been (and some southward tilting of the drainage basin may be invoked) turned southwesterly down the vale, behind the wall of hills, and "finally escaped seaward through the partly filled depressions of lower transverse stream valleys." And Fig. 37 shows this changed result, which probably remained constant with deepening channels and more and more accentuated drainage, the small streams forming on the eastern slopes of the hill ranges being unable to capture again these swelling trunk lines of flowage. Thus, the Connecticut and Housatonic Rivers turned westward into the Long Island Sound depression, and regained the ocean by the Hudson River canon; the Delaware River also turned sharply, and finally flowed into Delaware Bay; the Susquehanna River turned southerly and became confluent with the Potomac; and the Potomac, instead of crossing Maryland, submitted to the lateral thrust and entered Chesapeake Bay. Succeeding the previous formations the great Ice Age dawned, and a varied series of Quaternary deposits completed the outline and raised the superficies of Long Island. Thei coarser, more obvious, and latest features of this re-