192 PHYSIOGRAPHY AND GEOLOGY OF THE COASTAL PLAIN PROVINCE. 



The Patuxent Formation. 



The Patuxent formation is similar both in lithologic character and in 

 fossil content to the Patuxent formation of Maryland where the deposits 

 were first described under this name. The materials comprising the Patux- 

 ent in both areas are in a marked degree arkosic and predominantly arena- 

 ceous with layers and lenses of clay from which the plant fossils have 

 been largely derived. The arenaceous beds are universally cross-bedded 

 with many pebble bands and coarse beds of gravel. Overlying the Patuxent 

 formation in Maryland is a deposit of clay, often lignitic, called the Arundel 

 formation, that was evidently formed in the post-Patuxent valleys soon after 

 the close of the Patuxent epoch since the flora shows few if any changes 

 from that of the preceding Patuxent. The Arundel formation has furnished 

 many Dinosaurian remains. The Patuxent formation includes the James 

 Eiver and part of the Eappahannock series as well as portions of the 

 Aquia series earlier described by Ward. 



When a comparison is instituted between the Patuxent formation of 

 Virginia and the Patuxent and Arundel formations of Maryland the follow- 

 ing characteristic plant fossils may be recogiiized as common to the two 

 areas : 



Arthrotaxopsis grandis Fontaine Equisetum Burchardti (Dunk.) Brongn. 



Brachyphyllnm parceramofiuni, Fontaine Rogersia longifoUa Fontaine 



Cephalotaxopsis magnifolia -Fontaine (ladophlehis rirgiiilciisif: Fontaine 



Dioonites hiichiauiis (Ktt.) Rom. Cladophlebis ungeri (Dunk). Ward 



Nageiopsis longifoUa Fontaine C'feuopteris insignis Fontaine 



Nageiopsis zamioides Fontaine Nilsonia desinerve (Font.) Berry. 



Frenelopsis parccraniosa Fontaine Podozamites distavtinervis Fontaine 

 Equisetum LyelH Mantell 



The Patuxent formation is represented in North Carolina by deposits 

 which are evidently physically continuous with the Virginia strata although 

 the formation in southern Virginia and northern North Carolina is covered 

 at the surface by the transgression of the later Tertiary and Quaternary 

 sediments just as it is in narrower areas in Virginia and in Maryland. The 

 materials comprising the formation in North Carolina are similar in char- 

 acter but thus far no fossil remains have been found by which paleontologi- 

 cal comparisons can be made. The senior author of this report in discus- 

 sing the Lower Cretaceous formations of the Atlantic border region says:** 



"Deposits of Lower Cretaceous age are most extensively developed in 

 Maryland and northern Virginia, where the Patuxent (arkosic sands, gravel. 



aClark, W. B. Bull. Geol. Sec. Amer., Vol. xx. p. 647 (1908), 1910. 



