90 



SCIENCE. 



[Vol. XXI. No 524 



SCIENCE: 



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THE MIOCENE GROUP OF ALABAMA.' 



BY LAWRENCE C. JOHNSON. 



Five or six years ago it was doubtful if the Gulf States had any 

 well-defined Miocene. The brilliant discoveries of Mr. D. W. 

 LaDgdon,at Chattahoochee and at Alum Bluff on the Apalachicola, 

 set that question at rest for Florida; still there was general doubt 

 of any extension of the same into Alabama. 



Dr. Eug, W. Hilgard had defined and located the Grand-Gulf 

 Group in Mississippi, and conjectured it might be Miocene. But 

 he was not perfectly satisfied, and for want of fossils no paleon- 

 tologist would undertake a decision. This also it would have 

 been bold a few years ago to say had any continuation into Ala- 

 bama. 



Whilst at work for the U. S. Geol. Survey (1889), the Grand 

 Gulf was explored, to a considerable extent, in Louisiana, Miss- 

 issippi, and Alabama. 



Dr. Hilgard, for Mississippi, divided it lithclogically into two 

 phases: the first well seen at Grand Gulf, in which quartzites 

 prevail ; the second, most abundant, has the peculiar, character- 

 istic silicious clay-stones, found in such masses nowhere outside 

 of this group 



It was the fortune of the writer to observe two olher phases in 

 Mississippi : 



(1) The quartzitic phase — being only a phase of the next — 

 roughly estimated, extends from the north-west corner of the 

 formation on Big Black River, to a curved line drawn across 

 from R idney to Pelahatchie. It is most largely developed on 

 Bayou Pierre and Cole's Creek. For convenience it may be called 

 the •' Bayou Pierre Phase."' 



(3) The second, having very irregular boundaries, may have its 

 southern line drawn from Tunica, in Louisiana, by Co umbia. 

 Miss., by the mouth of Okatoma Cri-ek, by the Falls on Leaf 

 River near Estabuchie, passing to the southward of EllisviPe and 

 crossing Chickasawhay River between Winchester and Waynes- 

 boro. For convenience this division will be called the Fort 

 Adams, or the Ellisville phase. 



(3) More remote from the Great River, and southing farther, 

 the less silicious the formation becomes, at Hattiesburg, and 

 on that part of Leaf River from Okatoma to Rogers' Creek, and 

 on Chickasawhay above Leakesville, a third phase is exhibited, 

 abounding in phytogene remains — almost lignitic. This is the 

 Hattiesburg phase or formation. 



(4) A fourth manifests itself below Leakesville on the Chicka- 

 sawhay, on the Lower Leaf River and Pascagoula — being clays 

 of a more tenaceous quality — abounding in specks and nodules 

 of calcareous material, and in a tew places holding shells of mol- 

 lusks. One locality of the last, where first discovered, is the 



^ Recent Investigations made by Lawrence C. Johnson, for the Geological 

 Survey of Alabama, published In advance of the General Report, by permis- 

 sion of Dr. Eug. A. Smith, the Director. 



.Shell Landing below Roberts' Bluff, four miles south-west- of 

 Vernal postofBce. This is the Pascagoula phase or formation. 



The last three extend into Alabama, though the fourth lies 

 so deep under the great ridge of sands of Mobile County that no 

 overland outcrop has yet been discovered. In the deep boring at 

 Mobile it was reached at about 600 feet. The shells of the boring- 

 have been pronounced by Dr. Dall identical with those of Pasca- 

 goula, and a list of them furnished by him in this journal, Sept. 16,. 

 1892. 



The second and third phases have been traced across Alabama. 

 The second is finely developed at Healing Springs, in the northerQ 

 pan of Washington County. Briar Creek is about the boundary 

 between it and the Eocene, and southward of that it is frequently 

 exposed by the washing away of the surface sands, as far as the 

 head-waters of Bilbo Creek. 



The southern part of Washington is underlaid by the Hatties- 

 burg — the third phase. Many of the shallow ponds and cold 

 clay flats are to be accounted for by this fact; and so are the 

 ridges of better soil. Lignitic spots, coming to the surface where 

 drainage is sufficient, have weathered into limited areas of better 

 soil. Such a spot is on the southern branches of Basset Creek, on 

 the St. Stephens and State Line road. 



Baldwin and Escambia counties afford a continuation of these 

 parallel lines of silicious clay-stones, of ponds, and of cold clay 

 flats — not without places of better soil. This is the true origin 

 of the well-known strip of red lands on the high ridges northward 

 of Williams and Canoe stations — up West Escambia. 



Finally, in the vicinity of Brewton, Burnt Corn, Murder Creek, 

 and Conecuh River, expose sufScient of these three older phases 

 of the Grand Gulf as to leave no doubt with regard to the borizoQ 

 to which it properly belongs. 



Chalk Hill, at N. B. Dixon's (Sec. 1, T. 2, N. of R., 13 E), is a 

 repetition of Chalk Hill at Healing Springs, while the hills near 

 Castleberry on Murder Creek (Sec. 1, T. 2, N. of R., 10 E.), and 

 the exposures on Conecuh at Silas Bluff (Sec. 6 and 7, T. 1, N. R.^ 

 13 E ), at Coal Bluff (Sec. 7, T. 1, N. R., H E. ), and at 

 Roberts, Silas Creek (Sec. .5, T. 1, R. 12 E.) display the 

 Hattiesburg phytogene phase as fairly as Augusta on Leaf 

 River, — with the addition of molluscan fossils nut found in. 

 Mississippi. These are only in casts, true : because the clay- 

 sandy material, without lime, was too porous to retain calcareous 

 shells. 



Of the precise type and horizon of these fossils we are not left 

 in doubt; but to marshal our testimony on the subject, it will be 

 necessary to step across the line, and to bring forward by con- 

 tinuity the Miocene Marls of Florida, to wed these Grand-Gulf 

 clavs of Escambia. 



II Wakulla Springs, in the county of the same name, has a 

 peculiar lime-tone, which is found from St. iVlark's Bay into 

 Georgia. Generally fossils are few. The great coral, Astraea 

 Floridana or belea. and Orbitolites Floridana, ever present in. 

 the!ie warm seia-formations, are among them. In the deep exca- 

 vation at Weelaunee. Jefferson County, and the Bloxham well 

 near Tallahassee, fossils are more numerous and of greater 

 variety. 



On the Chattahoochee River, at Rock Island, between Port 

 Jackson and the mouth of Flint River, the Wakulla rocks again 

 manifest themselves, and upon the Eocene Vicksburg limestones 

 of Jackson County. Below the mouth of Flint, at the village 

 Chattihoochne, and forming the left bank of the Apalachicola 

 to Aspalaga landing — ten miles — is another phase of the older 

 Miocene. 



On Chipola River, at and above Chipola postofiBce, is another 

 phase of the older Miocene — the Chipola beds. These lie in and 

 upon the Chattahoochee more silicious form, in which the fossils 

 are very obscure. In the more calcareous ferruginous deposits of 

 Chipola, Farley Creek, and Ten-mile Creek, they are the best 

 preserved in the world. Even the Orbitolites are perfect, instead 

 of a mere impression. Neither of these formations can be saidi 

 to cross the Choctawhatchee River, westward. The obscurely 

 fossiliferous sandy rocks of Econfina, and at Douglas Ferry oq 

 the Choctawhatchee, may be assigned to the Chattahoochee. 

 But west of that great river the territory which should be occu- 



