Exposed sand bodies along modern shorelines, particularly those of the Atlantic and Gulf Coasts, are separated by gaps (Tidal inlets), exhibits an offset arrangement with respect to adjacent sand bodies, have convex tops, and presumably have flat bottoms. Many modern shoreline sand bodies, of which Cape Henry, Virginia, is a striking example, are made up of a series of overlapping beaches which are exposed as ridges of sand trending parallel with the coast. These ridges represent lines of beach growth.

Systems (called trends) of shoestring oil sands whose individual sand bodies are (1) separated by gaps containing no sand, (2) arranged en echelon, and (3) have convex tops and relatively flat bottoms, are present in the Pennsylvanian system in Kansas and Oklahoma. Evidence for at least one unusually large sand lens indicates that it contains growth ridges similar to those at Cape Henry. Somewhat similar belts of oil-bearing sand bodies are present in the Denver Basin in Colorado and Nebraska. The features described above are not so evident here, however. The sands appear to occur as lenses, most have convex tops and many have concave bottoms. The sand lenses in the Mid-Continent contain oil, gas, and salt water; those in the Denver Basin contain oil, gas, and fresh water.

Commonly, crude oils from different stratigraphic horizons differ signifircantly in composition (Research Committee, Tulsa Geological Society, 1947). In an area only 15 miles wide and 40 miles long oils from 43 pools in beds associated with the unconformity above the topmost beds (Ordovician) of the Arbuckle group contain 31 varieties of oils, and the oil in all pools is underlain by salt water. On the other hand, only one variety is present in oils from 33 pools in the Burbank sand (Pennsylvanian) distributed along an ancient shoreline 150 miles long. At places where the Bartlesville sand wedges out against the unconformable surface on the Mississippi lime the oil of the pools in the top of the Mississippi lime is like the oil of the pools in the Bartlesville sand. The facts suggest that the local environment of the source material determined the variety of oil in each pool, and that commonly oil has migrated only locally from source beds into the nearby or adjacent reservoir beds.

* --publication authorized by the director, U. S. Geological Survey.

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