Maryland Geological Survey 47 



same year Clark published a paper describing the progress of the work 

 on the Geology of the Middle and Northern Atlantic Coastal Plain, in 

 which the various formations were briefly discussed and the Lower Cre- 

 taceous age of the Patuxent and Arundel formations affirmed. The 

 Earitan was referred to the Upper Cretaceous and the Potomac Group 

 was limited to the Lower Cretaceous. Berry also published a brief paper 

 discussing the southward extension of the Patuxent formation into North 

 Carolina, and showing that the Arundel formation is absent in Virginia, 

 and that the Patapsco formation is transgressed and disappears in cen- 

 tral Virginia beneath Tertiary deposits. The latter author also pub- 

 lished several systematic papers upon some of the more important genera 

 of Potomac plants. 



The accompanying table shows the varying nomenclature of the more 

 important students of the Potomac deposits, commencing with that of 

 W. B. Eogers in 1841. 



BIBLIOGEAPHY 



1799 

 Latrobe, B. Henry. Memoir on the sand hills of Cape Henry in 

 Virginia. 



Trans. Amer. Philos. Soc, vol. iv, 1799, pp. 439-443, Philadelpliia. 



1809 

 Latrobe, B. H. An account of the freestone quarries on the Potomac 

 and Eappahannoc rivers. 



Trans. Amer. Philos. Soc, vol. vi, part ii, 1809, pp. 283-293. 



1824 

 Finch, John. Geological Essay on the Tertiary Formations in Amer- 

 ica. (Eead Acad. Nat. Sci. Phila., July 15, 1823.) 

 Amer. Jour. Scl., vol. vii, 1824, pp. 31-43. 



1829 

 Vanuxem, L., and Morton, S. G. Geological Observations on Sec- 

 ondary, Tertiary, and Alluvial formations of the Atlantic coast of the 

 United States arranged from the notes of Lardner Vanuxem. 

 Jour. Acad. Nat. Sci., Phila., vol. vi, 1829, pp. 59-71. 

 4 



