LOWER CRETACEOUS. 613 



The Lower Cretaceous formations in the area under discussion constitute part of a belt 

 of deposits of that age extending from Pennsylvania to eastern Alabama and are apparently 

 embraced within a single geologic province. North of central Maryland, where the most 

 complete sequence of the Lower Cretaceous strata is found, the Arundel and Patuxent for- 

 mations are gradually transgressed by the unconformably overlying Patapsco formation, 

 which in turn disappears by the overlapping of the Raritan formation in eastern Pennsylvania 

 and in New Jersey. 



Farther south, in Virginia, the Patapsco formation disappears near Fredericksburg and 

 does not reappear except in a single occurrence still farther south, and the Arundel formation 

 is not known to occur south of Potomac River. With the single exception above noted the 

 Patuxent is the only Lower Cretaceous formation exposed in south-central and southern Virginia, 

 where in the vaUey of James River some of the most f ossilif erous beds of this formation have been 

 found. Although separated at the surface from the deposits of the same formation farther 

 north, through the transgression of the Tertiary and Quaternary formations, the continuity 

 of the beds is assumed from the similarity of the flora, with its many identical species, as 

 well as from the characteristic lithology. 



Deposits formerly called the "Cape Fear" formation but now known to be a southward 

 continuation of the Patuxent formation of Virginia are found in North Carolina. Here again 

 the transgression of the Tertiary and Quaternary formations interferes with the continuity of 

 the outcrop, although there is no reason to doubt that the deposits are continuous beneath 

 the later strata. No fossils have thus far been discovered in the Lower Cretaceous deposits 

 of North Carolina, but the strata occupy the same stratigraphic position at the base of the 

 Coastal Plain Cretaceous here as farther north and are unconformably overlain by Upper 

 Cretaceous formations. The deposits are also strikingly similar to those of the Patuxent 

 formation in Virginia and Maryland and it seems to be a reasonable assumption that they 

 constitute part of the same formation. 



To the south of North Carolina similar deposits are known to extend through South 

 Carolina and Georgia into eastern Alabama. The more southern occurrences of the Lower 

 Cretaceous were long erroneously associated with the Tuscaloosa formation (Upper Cretaceous) 

 farther west in Alabama and Mississippi, but they are entirely distinct from that formation 

 both in stratigraphic position and in lithologic character, and they are separable everywhere 

 by marked unconformities from the overlying Upper Cretaceous deposits. According to the 

 evidence at present available, they are physically continuous with the Patuxent formation 

 farther north, whether or not the same formational name is employed throughout the province. 

 Notwithstanding the physical evidence in favor of a single formational unit at the base of the 

 Coastal Plain Cretaceous all the way from Maryland to Alabama, it must be admitted that 

 a transgressing sea throughout so extended a coast line might well have involved considerable 

 time for its accomplishment and if the transgression proceeded from the north toward the 

 south, as seems probable, the deposits in Alabama would necessarily be somewhat younger 

 than those in Virginia and Maryland. 



The Upper Cretaceous deposits within the area under discussion constitute part of a belt 

 that is known to extend from Massachusetts through the islands off the New England coast 

 and thence to the Gulf except at a few points where transgression or erosion has removed 

 evidence of their presence. The most complete sequence of strata is found in New Jersey, 

 north of which the later Upper Cretaceous formations are lacking, although the earher for- 

 mations continue through Massachusetts with their characteristic if somewhat incomplete 

 faunas and floras. To the south the Raritan and Rancocas formations finally disappear in 

 Maryland, but the intervening Magothy, Matawan, and Monmouth formations with their 

 characteristic faunas and floras can be traced through Maryland, can be recognized in Virginia 

 in the deep well boriags to the east of the Cretaceous outcrops, and reappear in North Carolina 

 in the Black Creek and Peedee formations. The boundary between the Matawan and the 

 Monmouth in the north, as well as that between the Black Creek and the Peedee in the south, 

 marks the division between the earher fauna and the later BelemniteUa americana fauna. The 



