The Raritan Clay Member consists of beds of dark gray silt and clay with subordinate 

 lenses of sand. Plant remains and lignitized wood are ubiquitous throughout the member 

 and coupled with the complete lack of marine-type fossils indicate that the clay was 

 probably deposited in a fresh- or brackish-water environment. Bore hole data indicate that 

 the Raritan Clay blankets the Lloyd Sand throughout Long Island except for locations at 

 the western end where substantial glacial erosion has removed the clay overburden and 

 permitted moraine material to be deposited directly on top of the Lloyd Sand. These gap 

 areas where the Lloyd Sand is directly overlain by glacial till are thought to be very 

 important for recharging depleted ground water reserves by natural ground water 

 percolation. 



The Magothy Formation represents the uppermost Cretaceous beds found on Long 

 Island. The name is applied to strata which closely resemble the Magothy stratigraphy best 

 exposed in parts of New Jersey. The Magothy Formation consists primarily of alternating 

 beds of silty sand, clay and zones of coarse sand and gravel. Because of its porous and 

 permeable character the Magothy is also an important ground water reservoir. (Kimmel, 

 1971.) 



Fuller (1914) considered the Jameco Gravel to be an early Pleistocene (Kansan?) 

 outwash deposit possibly deriving its detritus from a glacial still stand farther to the north 

 which evidently never extended as far south as Long Island. The Jameco is most extensively 

 developed in Queens County and either unconformably overlies the eroded Cretaceous 

 strata as in the northwestern section or lies directly on the crystalline bedrock. The extreme 

 irregularity and high relief surface topography of the Jameco suggests that it was subjected 

 to extensive erosion prior to deposition of the overlying Gardiners Clay. Because of its 

 physical character the Jameco is an important freshwater aquifer in western Long Island. 



There is a sharp lithologic break between the Jameco Gravel Formation and the overlying 

 Gardiners Clay Formation. The Gardiners is considered by many to be of Sangamon age and 

 deposited under quiet back bay brackish water environment very similar to present 

 conditions in Great South Bay. (Weiss, 1954.) It is characterized by dark gray or green-gray 

 silty clay with thin lenses of fine sand and contains a rich assemblage of formainifera. The 

 Gardiners is one of the few formations on Long Island which can be correlated over a 

 significant area by virtue of its microfossil content. According to Fuller (1914), the 

 maximum elevation of occurrence for Gardiners Clay, excluding elevation due to ice 

 pressure deformation, is 50 feet below present sea level, which may indicate that sea level 

 was at least 50 feet lower before the commencement of Wisconsin glaciation. Thickness and 

 areal continuity of the Gardiners Formation varies greatly; Athearn (1957) identified 

 Gardiners-type material from a deep boring sample retrieved in connection with site 

 foundation studies for a proposed U.S. Air Force Texas Tower, 60 miles south of Moriches 

 Bay, Long Island. The apparent Gardiners sample was retrieved 70 feet below sea floor 

 (overlain by coarse sand and fine gravel) at a water depth of 185 feet. 



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