Geologic Map of the Colonial Beach South 7.5' Quadrangle, Virginia Wayne L
Geologic Map of the Colonial Beach South 7.5' Quadrangle, Virginia Wayne L. Newell, Owen P. Bricker, and Meredith S. Robertson Stratigraphic section and map units of the Chesapeake Group , 77°00 , , ,, 38°15 57 30 , Correlation of Quaternary Map Units ** 55 , ,, Monr 20 77°52 30 , 38°15 10 5 7 Formations and Descriptions* 15 o Environments e 6 5 2 Littoral Estuarine Fluvial Colluvial Manmade Epoch Map Unit Period 4 Lithology Qb Qal Qs Qc af Era Thickness in Feet (+/-20) Colonial Qm Alluvium Beach deposits Swamp deposits Colluvium Artificial Fill Beach Sand, pebbles, silt, clay, Sand, gravel, pebbles, cobbles, Marsh deposits Silt, fine-sand, clay, organic Sand, silt, clay, pebbles, cobbles, boulders, Sand, silt, pebbles, clay, Bacons Castle Formation (late Pliocene) organic litter, cobbles, 20 boulders; well-sorted, bi-directional Organic litter, silt, clay and sand; poorly sorted and laminated, litter; poorly sorted, crudely poorly sorted, massive to discontinuously cobbles, and boulders; Upward-fining fluvial sequence includes medium to coarse gravelly sand and sandy gravel, poorly sorted, thick to very boulders; poorly to Qs planar cross-beds sub-parallel to shore occurs at head of tide and inter-tidal areas along the margins of laminated on flood plain bedded; matrix supported clasts and often chaotically thick bedded, trough cross-bedded; unit is light to medium gray; oxidizes to yellowish orange. Pebble to cobble-sized moderately well sorted in face and washover fans of sand bars. Popes Creek estuary, and in the fill of the wetlands of Bridges surfaces and in old discontinuous pebble horizons quasi-parallel intermingled.
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