Special Report 10 of the State of New Jersey: Department of Conservation and Economic Development, Division of Water Policy and Supply discusses how the Newark area is underlain by formations of Recent, Pleistocene and Triassic age, and the geology and hydrologic properties. Attention is called to the important influence of a buried valley in the rock floor beneath the Newark area on the yield of wells located within it. Data on the fluctuation of the water levels and variation in pumpage are presented, and their significance discussed. The beneficial results of artificially recharging the aquifers in one part of the area are described. Also presented is information concerning the intrusion of salt water into certain parts of the ground-wat...