URBAN STORM SURGE PROTECTIVE MEASURES-SYNTHETIC DUNE CONSTRUCTION - COMPARISIONS TO JURASSIC SAND DUNES FROM LOW STANDS THRU HIGH STANDS SYSTEM TRACT FACIES

The Rockaway Peninsula is in the 100 and 500-year flood zone, with potential sea level rise of between 8- 31 inches ( 20.32-78.7cm) from 2000 to 2050, and 15-75 inches ( 38.1-190.5 cm) for the entire 21st century.. The Peninsula contains 124,000 residences , with cumulative real estate assets worth 15 billion dollars. In 2012 Super Storm Sandy removed 1.5 million cubic feet of sand from the Peninsula.

Massive construction and population increases have continued on the Peninsula. In 2013 an environmental impact study of the effects and possible future steps for coastal protection was done under then Mayor Bloomberg utilizing a team of geologists and engineers and concluded a dune field would significantly protect the coastline.

The U S Army Corps of Engineers, New York District, is constructing significant rock jetties and synthetic dunes over the 10-mile coastline at a cost of over 700 million dollars. Over 2 million cubic yards of sand have been redeposited from dredging to the beach from near shore accumulations. A massive undertaking including the multi-step synthetic dune construction, involving a cement and sand bag nucleus covered by sand and salt tolerant greenery for dune anchoring.

Sensitivity of dunes to sea level fluctuations can be analogous to the well bore cores (15,000’) Jurassic dune fields of the Norphlet Formation in the Gulf of Mexico, which reflect significant dune migration from a transgression from low stand to high stand system tract facies. Provenance of the Rockaway Peninsula is due to Hudson River transport, erosion from the metamorphic Cambro-Ordovician Manhattan Schist, Fordham Gneiss, and Inwood Marble, part of the Northern Appalachians. Surface sediment samples contain well sorted quartz and other material grains. In comparison the Jurassic Norphlet Formation contains quartz grains rounded to sub angular derived from the southern Appalachian forelands. Mapping based on the stratigraphy from hydrocarbon exploration wells over the past 40 years have increased the extent of the dune fields from onshore Alabama to offshore in the Gulf of Mexico, truly sensitive to relative sea level fluctuations.