The given coordinates will put you at one of the sites to collect data for this earthcache. Sites do not have to be visited in any particular order but collecting the data during the same day is encouraged.
New Jersey Geologic History
The New Jersey Atlantic Ocean coastline is roughly 130 miles in length and can be classified into three different shoreline types depending on the purpose of the classification scheme. The New Jersey upland along the coast is composed of gravel, sand and silt deposits. All processes creating these sediments predate the present shoreline by millions of years. None of the sediments exposed at the surface in Monmouth, Ocean, Atlantic or Cape May Counties are cemented to form bedrock like that found along the New England coast. Since the geologic layers did not harden into rock, they erode easily under marine processes like wave action or tidal currents. These sediments are the source of all modern New Jersey beaches either directly by erosion or indirectly by the reworking of other deposits formed from these older sediments prior to the present sea level rise. The rise in global sea level has been occurring for the past 20,000 years at a variable rate, following the melting of the last great ice sheet covering northern North America. The local change has been in the range of 350 feet to 400 feet vertically, which has produced a long-term westward migration of the shoreline. The "New Jersey" shoreline lay at the edge of the continental shelf 20,000 years ago, 80 to 90 miles to the east of the present coast. As the ice sheets melted and retreated into Canada, the ocean marched across the relatively flat continental shelf constantly changing the position and configuration of the New Jersey shoreline. Lands mentioned in 17th Century records are now ocean, having vanished as the ocean continued its march westward in position and upward in elevation. The pattern followed stream channels back up the valley, flooding low areas first allowing the growth of white cedar trees, then salt marsh grass as tide water reached any particular point.
Large, shallow bodies of water consisting of open bay and salt marsh lie landward of the barrier island shoreline. The NJ coastal plain comprising the mainland is separated from the beach and dunes by a half mile to three miles of relatively recent sediments, which begin in Bay Head, and extend south to Cape May Point, NJ. Tidal inlets divide the barrier islands from each other. These inlets serve to divide the shoreline distribution of beach sand into cells roughly corresponding to the distance between the individual inlets. The gentler seaward slope of the southern New Jersey coastal plain has allowed a wider coastal zone and the inclusion of regions where a stream's current meets the ocean. There are numerous places where you can observe this interaction between the upland edge and the barrier islands.
Strong tidal currents move sand into and out of the narrow inlet channels between two barrier islands. As current flow slows down in either the bay behind the barrier chain, or in the open ocean, the sand is deposited in what are termed flood- or ebb-tidal deltas (respectively). The more significant of these two features relating to beachfront changes is the ebb-tidal delta. The delta is essentially a shoal surrounding the inlet and extending up to several thousand feet along the oceanfront beaches on either side of each inlet. This shoal produces shallow water seaward of the beach on the adjacent barrier islands. All waves slow down as they enter shallow water. This, coupled with the refraction that occurs as the wave reaches the delta, results in substantial alteration to the wave energy and approach direction to the barrier beach in the immediate vicinity of the inlet mouth. The delta shoal acts to shield beaches that lie behind the arc of the shoal from some of the approaching wave energy. Larger waves break first on the delta margin, losing energy. This combination of effects yields very complex equilibriums, which vary from year to year and even seasonally. The inter-relationships of wave energy distribution and beach changes around inlets have only been recognized in the past 30 years. These relationships are only now being quantified so that management decisions on inlet navigation dredging and beach nourishment projects can take inlet-beach dynamics into account.
Recent scientific studies have shown that the tidal inlets have much greater impact on the loss or addition of sand(on individual barrier islands) than the steady flow of currents near the shore to the south. If the sand moved south toward Cape May Point in a never-ceasing stream, then Cape May Point and Cape May City should be buried in beach sand. The fact is, however, that both of New Jersey’s southern-most communities were sand starved as major man-made structures and indirect, development-caused changes contributed to shoreline instability. The Army Corp Of Engineers has completed three beach restoration projects in Cape May County in the past decade. These programs are an attempt to restore the balance between sediment transport and sediment supply. Monitoring of the results will provide quantitative facts on sand requirements, loss rates, and re-nourishment schedules so that financial planning can match the demand for coastal beach stability.
(used with permission from Richard Stockton College of New Jersey Coastal Research Center)
There are nine survey sites on the Atlantic County shoreline. Loss of sand has occurred along the shores of Absecon Island even with beach replenishment at various sites over the years. To receive credit for this earthcache, you must visit the three locations listed below, along the shoreline of Absecon Island. The sites are easily accessible although there may be a high muggle factor during the summer months. Your best times to go will be early morning or evening. Email your answers and do not include them in your log.
Dorset Avenue beach, Ventnor City (N 39° 20.300 W 074° 28.520)
Benson Avenue beach, Margate City (N 39° 19.260 W 074° 30.650)
17th Street beach, Longport (N 39° 18.425 W 074° 31.860)
1. At each location, estimate the distance from the ocean to the breakwall in yards.
(Suggest using your GPSr to mark either the breakwall or the water's edge as a waypoint and then walk to the other to measure.)
2. Use a ruler or yardstick to measure the DEPTH OF THE SAND (not the height of the exposed wall) at the breakwall in inches.
3. Based upon your measurements, do you think the amount of sand is increasing or decreasing here? Why do you think so?
4. Observe the tidal condition. Is it high tide, low tide or somewhere in between?
Please include in your log the time you made your observations and feel free to include pictures of your observations with the log.