McGee — Southern Extension of Appomattox Formation. 33 



aters — the whole simulating a mountain crest-line with its 

 peaks, aretes, cols, gorges and amphitheaters, save that every 

 summit is blunted. This striking configuration tells a signifi- 

 cant story, but one too long for repetition here — it suffices that 

 it tells of a time when the land stood higher and the rivers 

 were made more energetic than to-day. Now over this irregu- 

 lar surface the Appomattox was evidently spread mantlewise, 

 just as over the qualitatively similar though less strikingly em- 

 phasized surface of the Grand Gulf ; and here as there the post- 

 Appomattox rivers sought their old courses, and the new drainage 

 system corresponds substantially with the old ;* but the lower 

 base level of to-day has tended to develop a flatter surface than the 

 old, and while remnants of the orange loam are frequently caught 

 on the crests and lodged in the amphitheaters, they have been 

 commonly removed from the higher altitudes and are gener- 

 ally confined to the lower levels. 



Perhaps the Appomattox merges into the phosphate-bearing 

 Pliocene beds of South Carolina; probably it is continuous 

 with some of the newer off-shore deposits of Florida ; unques- 

 tionably it represents but the landward portion of one of a 

 vast series of deposits which at some distance beyond the 

 present shores of Ocean and Gulf are unbroken ; but certainly 

 there is a great unconformity, first between the Pleistocene 

 Columbia and the Appomattox, and second between the Appo- 

 mattox and all of the subjacent Neozoic formations yet sat- 

 isfactorily discriminated within the Atlantic and (jrulf Slopes. 



Taxonomy. 



No fossils have thus far been found in the Appomattox 

 formation except at Meridian, where Johnson has found it to 

 contain well preserved magnolia leaves apparently identical 

 with those of trees now growing in the same vicinity. Its 

 stratigraphic position, unconformably below the Pleistocene 

 and unconformably above the (probably) Miocene Grand Gulf 

 formation, indicates an age corresponding at least roughly with 

 the Pliocene. 



The formation represents a considerable part of a more or 

 less vaguely defined series of deposits variously called "Orange 

 Sand," "Drift" or "Quaternary," "Southern Drift," etc., by 

 many geologists ; but since this vaguely defined series included 



*The history of renewal of buried drainage systems iu the eastern Gulf slope 

 is recorded in wonderful fulness and clearness. Three and even four times has 

 the autogenetically sculptured surface of the Choctaw buhrstone beeu submerged 

 and mantled with sediments, only to rise and resume more or less fully its old 

 aspect under the influence of waterways following the old lines. Such resur- 

 rected, or palingenetic, drainage and sculpture is characteristic of much of Mis- 

 sissippi. 



Am. Jour. Sci. — Third Series, Vol XL, No. 235. — July, 1890. 

 3 



