Bulletin, geologic series 23

The greensand marl belt of Now Jersey extends across the State from the vicinity of Sandy Hook at the northeast to Delaware River near Salem at the southwest, a distance of about 100 miles. It is crossed at many places by railroads and by streams that flow into Delaware River. The potash in the greensand marl occurs chiefly in the mineral glauconite, which is essentially a hydrous silicate of ferric iron and potassium. Nearly all the Cretaceous formations contain glaneonite, but only three contain sufficient amounts to be considered commercially important, though in some others it is locally abundant. These three are the Navesink (the lowermost), Hornerstown, and Manasquan marl which are described respectively as 25 to 40_ 30, and 25 feet thick. The marl beds, which form part of the Coastal Plain strata, strike about N. 55° E, and dip about 33 feet to the mile southeast, but there are some variations. The gently inclined and poorly consolidated beds that compose the marl arc beveled by erosion and covered to a greater or less extent by later deposits. Five type areas were explored by borings and made the basis of specific estimates. These were at Salem and Woodstown, in Salem County; Sewell, in Gloucester County; Somerdale, in Camden County; and Elmwood Road, in Burlington County. The data gathered from borings were supplemented by well data, both published and unpublished, and by field data on file in the office of the State department of conservation and development