202 D. W. Langdon— Tertiary of 



formations, of which we have given only some of the promi- 

 nent features. While a great work has been done by Rogers 

 and others, the material of the field is far from being exhausted ; 

 and the amateur student can readily find access to any particular 

 formation or groups which he ma}' desire to make a special 

 subject of stud}'. 

 Washington and Lee University, Lexington, Virginia, 1885. 



Art. XX. — Observations on the Tertiary of Mississippi and 

 Alabama, with descriptions of new species ; by D. W. LANG- 

 dozst, Jr., Geological Survey of Alabama. 



In the following notes will be found a statement of some per- 

 sonal observations upon the Tertiary of Alabama and Mississippi, 

 made the past season, which may help to settle the point of 

 dispute recently raised over the stratigraphy of the region. 



Just above the Yicksburg and Meridian Eailroad bridge 

 over the Pearl River at Jackson, Miss., and on the west bank, 

 the following section is exposed: 



Pearl Piver Section, No. 1. 

 Surface soil and drift pebbles 8 feet. 



1, Calcareous blue joint clay, very much like the "Rotten 



limestone " of the Cretaceous. Fossils generally de- 

 composed, Pecten nuperus Con., Ostrea pandmformis 

 Gabb, well-preserved. Lower portion full of a mad- 

 repore known locally as " nigger heads " 15 feet. 



2. Fossiliferous marl containing the "Jackson" shells, 



slightly glauconitic. Upper portion reddish, lower 



part bluish gray. Not very sandy 10 feet. 



From a point a few hundred yards below the railroad bridge, 

 following the river down, there are seen no exposures of Ter- 

 tiary strata until arriving at a small bluff on the east side of 

 the river and estimated to be about a half mile south of Jack- 

 son. Here an exposure of the calcareous clay (No. 1, of the 

 above section) six inches thick, is seen just above the water. 

 This streak continues for two miles, never showing more than 

 two feet of strata until reaching Richmond Lake Bluff, four 

 miles a little west of south of Jackson, where it shows four feet 

 thick overlaid by river alluvium. The last of these clays dis- 

 appear below the water about a half mile further down the 

 river. The fossils of this clay are principally Ostrea pandte- 

 formis Gahb,Venerecardia planicosta Blain., and other shells too 

 friable to be distinguished, as well as fragments of Crustacea. 

 The outcrops up to this point are not extensive enough at any 

 one place to estimate the amount of the dip, but the direction 



