Stratigraphy of Newly Exposed Quaternary Sediments, Eastern Orleans Parish, Louisiana

Abstract

Five Late Quaternary stratigraphic units are exposed at the Lake Carmel borrow pit in eastern Orleans Parish. These are, in ascending order: 1) deltaic eqwvalents of Deweyville terrace alluvium (Wisconsin); 2) a buried soil zone, herein informally named "Little Woods paleosol" (late Wisconsinearly Holocene); 3) bay-sound clay, herein formally designated the "Michoud Formation" (middle Holocene); 4) barrier bar sand of the New Orleans trend (middle Holocene); and 5) St. Bernard prodeltaic and delta front deposits (late Holocene). This succession of beds records the envirorunental history of the vicinity of the borrow pit as the following sequence of major events: 1) the emergence of a late Pleistocene delta lobe and pedogenic alteration of deltaic deposits; 2) the subsequent inundation of the southern Lake Pontchartrain and New Orleans area by transgressive Gulf waters forming the Pontchartrain Embayment; 3) progradation of the New Orleans barrier trend across the mouth of the embayment; and finally, 4) encroachment of a St. Bernard delta lobe on the New Orleans trend and eventual isolation of the embay
men! from the Gulf of Mexico to form the present Lake Pontchartrain.