中部密西西比湾的地层建造表明至少从晚侏罗纪就在现代密西西比河近似的同一流路上显然有一较大的河流连续发育。重要的三角洲堆积出现在 Smackover 石灰岩(晚侏罗纪)和最新的地层中。从侏罗纪持续到现在的这条河流在这里被视为古密西西比河。 Stratigraphic construction in the central Mississippi Bay indicates that at least a continuum of large rivers apparently develops at least from the same Jurassic-to-modern path on the modern Mississippi. Important delta deposits occur in Smackover limestone (Late Jurassic) and the later strata. This river that stretches from the Jurassic to the present is regarded here as the ancient Mississippi.