On a small, homemade barge, built from the skeleton of an old ship, a gray slurry of bay bottom sand flows out, of a pipe into a bucket. Two scientists, a well driller and two student interns drill a hole in the floor of the Indian River Bay. They'll install a very long pipe into the hole and use it to monitor groundwater - how much flows 'into the bay, how salty it is and how many nutrients it carries with it.
In 2000, A. Scott Andres, a senior scientist and hydrologist with the Delaware Geological Survey, released findings that disclosed a unique formation at the swamp.
In geologic time, the swamp isn't that old.
It formed about 22,000 years ago in a fresh-water, cold-climate marsh and boreal forested swamp.
Organic matter started building up and a cold wind blew in silt, clay and sand from nearby dunes and surrounding high ground. More sediment washed in with runoff from streams.
Thin sheets of sand likely spread during times when the land thawed.
Conditions began to change about 10,000 years ago as the climate warmed, forming a temperate-forested swamp, bog and flood plain.
There was more erosion and movement of organic-rich sediment to the fresh-water swamp. Today, it's considered the northernmost Southern forest on the East Coast.
The Delaware Geological Survey (DGS) has published a new geologic map of the Rehoboth Beach area in eastern Sussex County entitled Geologic Map of the Fairmount and Rehoboth Beach Quadrangles, Delaware. Geologic Map 16 presents the results of research by Kelvin W. Ramsey of the DGS.
The geologic history of the surficial units of the Fairmount and Rehoboth Beach quadrangles is that of deposition of the Beaverdam Formation and its subsequent modification by erosion and deposition related to sea-level fluctuations during the Pleistocene. The geology reflects this complex history both onshore, in Rehoboth Bay, and offshore. Erosion during the late Pleistocene sea-level low stand and ongoing deposition offshore and in Rehoboth Bay during the Holocene rise in sea level represent the last of several cycles of erosion and deposition.
The purpose of this report is to provide information on the mining industry of Delaware as an essential component of a growing economy. The industry, particularly in sand and gravel mining, must deal with uneven regulation, land use competition, and environmental pressures. It is hoped that the information gathered here will assist planning and regulatory agencies as well as an interested general public in evaluating the role of the extractive mineral industry.
This investigation was undertaken to locate deposits of rock, sand, gravel, fill and borrow in northern New Castle County which may be potential sources of material for highway construction, and to prepare maps and descriptions of the surficial earth materials relative to their geologic and engineering properties.
