64 The Lower Cretaceous Deposits of Maryland 



Supposed, but altogether doubtful, angiosperms, the most ancient 

 known, are represented by the genera Rogersia, Protecephyllum, and 

 FicopJiyllum, which perhaps should be considered the remains of foliage 

 of the gymnospermous order Gnetales. 



The known fauna of the Patuxent is represented by a single fish found 

 in the James Eiver area, but it is extremely probable that the rich 

 dinosaurian fauna of the overlying and closely related Arundel forma- 

 tion flourished druring Patuxent time, since in the west the representa- 

 tives of this fauna occur in the Morrison formation conformably below 

 the Kootanie formation, which carries the representatives of the Patux- 

 ent flora. 



THE ARUNDEL FORMATION 



Name and Synonymy. — The Arundel formation was named from 

 Anne Arundel County, Maryland, where the deposits of this formation 

 were first recognized as a distinct unit by Clark and Bibbins.^ It is 

 the lower portion of the " upper oolite,^' or " Iron-Ore Clays " of Tyson, 

 a part of the " Variegated Clays " of Fontaine, and McGee, and of the 

 " Baltimorean " of Uhler, and is the equivalent of the ""' Iron-Ore series " 

 of Ward. 



Areal Distribution. — The Arundel formation outcrops in an irreg- 

 ular and partially interrupted belt that extends from the head of Bush 

 Eiver, in Harford County, to Washington, D. C. This belt adjoins that 

 of the Patuxent formation to the west, and reaches its maximum width 

 of 7 miles in the northern portion of Prince George's County, its usual 

 width being from 3 to 5 miles. Where the formation is not overlain by 

 later deposits it generally forms broad dome-shaped hills. The observed 

 vertical range of the Arundel deposits is from 300 feet above tide to the 

 landward to 368 feet below to the seaward. 



LiTHOLOGic Characters. — The Arundel formation consists typically 

 of drab, more or less lignitic clays, carrying nodules, geodes, flakes, and 

 ledges of earthy iron carbonate or siderite. The nodules or geodes are 



'^Loc. cit., p. 485. 



