Will,
This was taken from Howard P. Boyd's book, "A field Guide To The Pine Barrens Of New Jersey" I hope this helps, and by the way get your map of New Jersey out.
"The pine barrens is a broad expance of relatively level land lying between the tidal strip along the east coast and the Delaware river valley on the west. The area lies variously from one to 10 miles inland from and roughly parallel to the seacoast, and formerly extended south nearly 90 miles from Asbury Park and Freehold in Monmouth County to Woodbine and Cape May Court house in Cape May county. It also extends, or formerly did extend, inland across southern New Jersey in places nearly 40 miles in width to New Egypt in Ocean county; Wrightstown, Pemberton, Vincentown, and Medford in Burlington County; Atco, Pine Hill, Clemonton, and Blackwood in Camden County; Williamstown, Glassboro, and Newfield in Glouster County; Elmer, Parvin State Park near Centerton in Salem County; and Bridgeton, Vineland, Millville, and Port elizabeth in Cumberland County."
" THE PINE BARRENS IS A UNIQUE REGION OF SANDY, ACIDIC, AND STERILE SOILS MADE UP OF COARSE SANDS AND GRAVELS DEPOSITED BY ANCIENT SEAS. tHESE ACIDIC SOILS ARE HIGH IN IRON CONTENT BUT LOW IN CALCIUM, MAGNESIUM, AND POTASH.wATER DRAINS RAPIDLY THROUGH LAYERS OF THESE POROUS SOILS TO FORM VAST UNDERGROUND RESERVOIRS, LEAVING THE SURFACE DROUGHTY IN SPITE OF AN AVERAGE RAINFALL OF NEARLY 45 INCHES PER YEAR.
"THE PINE BARRENS IS A REGION FORESTED WITH PINES, OAKS, AND CEDARS, WITH AN UNDERSTORY OF MAINLY HEATH-LIKE SHRUBS. IT IS A REGION THAT LACKS IN DIVERSITY OF PLANT FORMS, WITH A RESULTANT IMPACT UPON ANIMAL FORMS. THE UNIQUE FEATURES OF THE PINE BARRENS ECOLOGY RESULT IN AN UNUSUAL FLORA AND FAUNA. a FEW PLANTS AND ANIMALS ARE KNOWN ONLY FROM THE NEW JERSEY PINE BARRENS OR FROM SIMILAR NEARBY "ISLAND" HABITATS. sEVERAL OTHERS WHICH ALSO OCCUR HERE ALSO OCCUR ELESWHERE IN A FEW ISOLATED AREAS MANY MILES AWAY, WHILE MANY SPECIES THAT ARE COMMON HERE ARE RARE ELSEWHERE."
"It is generally beleived that present pinelands flora and fauna developed only after the retreat of the Wisconsin Ice, or within the past 12,000 to 10,000 years."