Potomac group

Well-Water Samples from the Potomac Group and Raritan near Camden, New Jersey"... 

Figure 8. Location of the New Jersey study area and generalized pH values of ground water in the Potomac Group and Raritan and Magothy Formations as shown by contours, 1966-67 crosshatching denotes the outcrop area of the formations...

River, in Prince George County, Virginia, USA (see Friis et al., 1994,1995). Palynologi-cal analyses (Christopher in Dischinger, 1987) indicate that the sediments at this locality can be referred to the basal part of subzone IIB in the palynological zonation established for the Potomac Group by Brenner (1963) and others (Doyle, 1969 Doyle and Hickey, 1976 Doyle and Robbins, 1977 Hickey and Doyle, 1977). Subzone IIB is of Middle Albian age, but may extend down into the Early Albian (Doyle, 1992). 

Derivation of generic name - From the native American Algonquian name Cohongarooton for the Potomac River, after which the Potomac Group is named. 

Type stratum - Patapsco Formation, Potomac Group. 

Brenner, G. J. (1963). The spores and pollen of the Potomac Group of Maryland. Maryland Department of Geology, Mines and Water Resources Bulletin, 27, 1-215. 

Doyle, J. A. (1992). Revised palynological correlations of the lower Potomac Group (USA) and the Cocobeach sequence of Gabon (Barremian-Aptian). Cretaceous Research, 13,337-349. 

Doyle, J. A. and Hickey, L. J. (1976). Pollen and leaves from the mid-Cretaceous Potomac Group and their bearing on early angiosperm evolution, pp. 139-206 in Beck, C. B. (ed.). Origin and Early Evolution of Angiosperms. New York, NY Columbia University Press. 

Lauraceous flowers from the Potomac group (mid-Cretaceous) of eastern North America. Botanical Gazette, 151, 370-384. 

Friis, E. M., Eklund, H., Pedersen, K. R. and Crane P. R. (1994). Virginianthus calycanthoides gen. et sp. nov. - A calycanthaceous flower from the Potomac Groups (Early Cretaceous) of eastern North America. International Journal of Plant Sciences, 155,... 

Upchurch, G. R. (1984). Cuticular anatomy of angiosperm leaves from the Lower Cretaceous Potomac Group. I. Zone I leaves. American Journal of Botany, 71, 192-202. 

RICHARD A. CONWAY, Union Carbide Corporation (retired), Charleston, West Virginia GILBERT F. DECKER, Walt Disney Imagineering, Glendale, California LAWRENCE J. DELANEY, Delaney Group, Potomac, Maryland (until 12/31/99)... 

Humin isolates from sediments of the Mew York Bight and Potomac River estuary have spectra that are notably different in that aromatic carbons are the dominant components. The spectra resemble that of humin isolated in the same manner from an aerobic soil from southern Georgia (Figure 5). However, unlike the humin from soil which shows a significant peak for carboxyl carbon (175 ppm), spectra of humin from the New York Bight and the Potomac River do not display a discreet peak at 175 ppm and appear to be depleted of carboxy 1/amide groups. Elemental data for these humins (19) are consistent with the NMR results. Atomic H/C ratios of less than 0.8 are not typical of humic material but more like those of highly aromatic coal or coal-like products. The NMR spectra also resemble... 

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