42 



SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1916. 



Oligocene: 



Alum Bluff formation: Feet. 



Cross-bedded laminated sands with clay lam- 

 inae and thin distorted clay lenses of small 

 extent. The sands are locally tliicker 

 bedded and argillaceous, especially in the 

 upper part, where they are in places packed 

 witli tlie distorted detached rays of aSabal- 

 like palm. In tlie lower part they are more 

 evenly bedded an<l less argillaceous, being 

 composed'largely of a somewhat coarser gray 

 iron-stained sand witli vegetable matter 

 aggregated in definite but not everywhere 

 liorizontal layers. Here and there are thin 

 iron crusts, and some of the more argilla- 

 ceous laminae arj bluish in color. Leaf im- 

 pressions are much more abundant and 

 varie^l in these lower layers. The tliick- 

 ness is variable, the maximum observed 

 being about 10 



Gray calcareous compact massive, in places 

 slightly phosphatic sand, somewhat fos- 

 siliferous; tliickness about 12 



Cliipola marl member: Compact ferruginous, 

 abundantly fossiliferous argillaceous sand 

 carrj'ing C)rthaula.x and other characteris- 

 tic Oligocene invertebrates; thickness 

 exposed 3^ 



most Oligocene or basal Miocene flora, prac- 

 tically the only one luiown in North America. 

 In Forrest County, Miss., in beds included 

 by L. C. Johnson in the Hattiesburg clay (see 

 PL VII, A, p. 56), I discovered in the summer of 

 1910 a small flora that appears to be sjTichro- 

 nous with that at Alum Bluff. The exact lo- 

 caUty is on the south side of the New Orleans, 

 Mobile & Cliicago Raih'oad, 1 mile east of Rag- 

 lan, and the outcrop shows the following section 

 (see also fig. S) : 



Section near Raglan, Miss. 



Feet. 



1. Compact reddish argillaceous sand 0-12 



2. Light sandy clay 1-2 



3. Compact argillaceous lignite or l>rown lignitic 



clay 2 



Unconformity (local?). 



4. Yellowish or gray argillaceous fine sand or sandy 



clay, grading into underlying beds 10 



.5. Similar materials of greenish color, weathering 

 yellowish, irregularly bedded and carrying 

 iMge numbers of poorly preserved plant re- 

 mains, mostly palm rays; grades into under- 

 lying beds; thickness about 4 



G. Yellowish or greenish much-jointed sandy clay.. 6 



_Track level ISfeet above 

 low water of Leaf River 



Figure 8. — Section of Hattiesburg clay near Raglan, Miss. 



Alum Bluff is a most mteresting spot to the 

 physiogi-apher, because of the striking contrast 

 in topogi-aphy between the east and west banks 

 of the river; to the geologist, because it is a 

 classic locality for the so-called Old Miocene 

 and represents also the oldest knowai southern 

 outcrop of the Chesapeake Miocene; and to 

 the botanist, because in the wooded and damp 

 ravines along the bluff are to be foimd two 

 isolated gymnosperms, both relics of bygone 

 floras, Taxus finridana NuttaU and Tumion 

 taxifolium. (Arnott) Greene. Alum Bluff is of 

 particular interest to the paleobotanist, be- 

 cause it furnishes a representation of an upper- 



Numbers correspond to those given in the section in the text. 



The plants in the sands at both the localities 

 mentioned above are few and very friable. 

 Collections could not be made in the usual way, 

 and as my improvised method jjroved very 

 satisfactory it is worth describing. A small 

 excavation in the loose, slumped sand was 

 lined with a large piece of burlap. This was 

 partly filled with plaster. While the plaster 

 was still soft the sandy specimen was placed 

 in it, the face of the specimen being left about 

 on the level of the plaster. After the plaster 

 had set the face was thickly covered with cot- 

 ton, over which the free ends of the burlap 

 were wrapjx-d and tied firmly. Every speci- 



