RECENT INVESTIGATION OF COASTAL RLAIN FORMATIONS 651 



surface is not as extensively dissected as the Sunderland terrace, and near its 

 inner margin are found many buried valleys that were cut at the close of Sun- 

 derland time. 



Below the Wicomico terrace, and encircling it, is the third or youngest ter- 

 race of the Pleistocene, which has been called the Talbot. The landward mar- 

 gin of the Talbot terrace is from 40 to 60 feet in height, from which elevation 

 it gradually declines seaward until it reaches nearly, if not quite, to sealevel. 

 The Talbot terrace has been but slightly dissected, compared with the earlier 

 terraces, and forms the coastal lowlands. It may also be traced as a low ter- 

 race far up the estuaries and river valleys until it also merges into true fluvia- 

 tile deposits. In North Carolina it divides into two terraces, constituting the 

 Chowan and Pamlico formations. 



All of these Pleistocene formations have been traced step by step throughout 

 the area in question, and present the same general characters everywhere. 



RECENT 



The Recent deposits consist of beaches, sand bars, sand spits, sand dunes, 

 flood plains, and other fluviatile deposits and humus. These deposits represent 

 the results of all the geological agencies now at work in modifying the surface 

 of the Coastal plain, and are variously developed in the different portions of 

 the region, dependent on the character of the adjacent formations and the dis- 

 tribution of the various streams and currents. A great Recent terrace, similar 

 in all particulars to those of Pleistocene date, is now being laid down beneath 

 the bed of the present sea and estuaries and along the border of the coast and 

 tidal streams. Beaches are frequently being formed, while great sand bars are 

 common. Sand dunes adjoin the coast, and are especially prominent in south- 

 ern Virginia and North Carolina, where from cape Henry southward they are a 

 conspicuous feature of the coastal topography. The rivers during flood are 

 constructing flood plains, which coalesce with the deposits of the estuaries. 

 Over the land surface the transfer of material and the development of soils, 

 with their accompanying humus, is going on everywhere. 



Comparison or the Atlantic Coast Formations with those of the Gulf 



AND OTHER AREAS 



The geology of the Gulf region presents many points of difference from that 

 of the Middle Atlantic Coast district, and yet certain comparisons may be insti- 

 tuted on the basis of the faunas and floras by which a correlation of the de- 

 posits in the two areas may be in many instances satisfactorily determined. 

 The similarity of materials is much more marked in the lower portions of the 

 series than in the upper, the Cretaceous and Eocene formations affording mauy 

 beds of like character and containing similar faunas. The later Tertiary de- 

 posits show marked differences, both in materials and fossils, and little attempt 

 has been made to correlate the strata. Comparisons likewise have not been 

 made in the case of the Quaternary formations. 



A correlation of the Cretaceous deposits of the Atlantic coast with those of 

 the eastern Gulf cannot be in all instances satisfactorily made, since the Gulf 

 Cretaceous series has never been worked out in detail, and much yet remains 

 to be done in the determination of the range of the species. Strata hitherto 

 called Tuscaloosa are found at the base of the Cretaceous series, in eastern 



