The filtered gravity map of the 48 contiguous states by Hildenbrand et al illustrates the relationships of anomalies in the Gulf Coast more clearly than previous (unfiltered) presentations. Gravity anomalies are recognized, which lead to the following hypotheses. (1) The passive margin of a late Precambrian to early Paleozoic rift underlies the Ouachita foldbelt from the Marathons through the end of the exposed Ouachitas in Arkansas. (2) A late Precambrian to early Paleozoic transform passive margin underlies the buried Ouachita-Appalachian connection in Arkansas, Mississippi, and Alabama. (3) A continuation of the rift passive margin underlies the Appalachians. (4) An early Mesozoic rift passive margin underlies southern Mississippi, south Louisiana, and coastal Texas. ( ) This Mesozoic margin has at least two transform offsets in southern Louisiana and southern Mississippi. (6) The Sabine uplift, the Monroe-Sharkey uplift, and other features along the Atlantic coastal plain are buried portions of a late Paleozoic island-arc complex. (7) The Florida platform is accreted Africa-South American continental material. These hypotheses are supported by structural, magnetic, and seismic data obtained over some of the features.

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