58 The Lower Cretaceous Deposits of Maryland 



the patuxent formation 



Name and Synonymy. — The Patuxent foTmation was so designated 

 from the Patuxent Eiver in Maryland, in the drainage basin of which 

 its deposits were first recognized as an independent formation and named 

 by Clark and Bibbins.^ It is in part the "feldspathic sandstone" of 

 Eogers, the " lower oolite " of Tyson, and the " Fredericksburg " or 

 "lower sandstone member" of Fontaine and McGee. It includes most 

 of the " James Eiver " and a part of the " Eappahannock " and " Aquia 

 Creek series " of Ward, and also a part of the " Baltimorean " of Uhler. 



Aeeal Distribution. — The Patuxent formation extends across the 

 State in an irregular and at times interrupted belt, some 5 or 6 miles 

 in average width, from the Delaware line through Elkton, Baltimore, 

 and Laurel to the city of Washington. It forms generally the landward 

 border of the Coastal Plain, although its outcrop is in places buried be- 

 neath later deposits while seaward its surface continuity is interrupted 

 by the principal water-ways, siuch as the Susquehanna, Gunpowder, Pa- 

 tapsco, and Potomac rivers. 



Outliers are found on the crystalline rocks to the west of the main 

 body of the deposits, the two most conspicuous being the outliers at 

 Catonsville and Lutherville. The former occupies one of the highest 

 levels containing Coastal Plain deposits while the latter is found in 

 a limestone valley a hundred feet lower than similar beds not far to 

 the southeastward. 



The Patuxent deposits in the Fall-line zone afford a very broken relief 

 in the vicinity of the stream channels. The exposed hillocks of Patuxent 

 materials with their slight cover of vegetation often suggest a bad land 

 topography. Patuxent deposits have been observed in Maryland from 

 over 400 feet in elevation near Catonsville to below 400 feet in a well at 

 Indian Head. 



LiTHOLOGic Character. — The materials constituting the Patuxent 

 formation are on the whole arenaceous, although argillaceous elements 

 likewise appear. The sands, which are predominantly cross-bedded, are 



1 Jour. Geol., vol. v, p. 481, 1897. 



