154 THE COASTAL PLAIX FOB^IATIOXS OF CECIL COOTTY 



clays is Lower Cretaceous. The formation rests unconformably on 

 the underlying Patuxent formation, and is overlain unconformably, 

 not only by the Raritan, which is the next succeeding formation of 

 the Potomac group, but also by the sands and gravels of the Lafayette 

 formation and the formations of the Columbia group. The Patapsco 

 formation occupies a belt extending across Cecil county, from the 

 Delaware line to the Susquehanna river and the head of the Chesa- 

 peake Bay, included roughly between the tracks of the Baltimore 

 and Ohio Railroad on the north and the north shore of Elk River on 

 the south. Throughout the northern portion of this belt the for- 

 mation is exposed on the hillsides, and throughout the southern portion 

 it is found at a lower level in the sides and bottoms of deep ravines. 

 Throughout the northern half of the belt it overlies the Patuxent 

 formation; throughout the southern half it is in turn overlain by the 

 Raritan. Exceptions to this general rule are found, however, in 

 some outlying areas, such as Egg Hill and localities near Eoys Hill 

 and Blythedale, where isolated portions of the Patapsco not only 

 rest on the Patuxent, but are also largely covered over with Raritan. 



The materials of the Patapsco are fully as varied and irregularly 

 developed as those of the Patuxent. They consist of variegated 

 clays and stratified and cross-bedded sandstones, gravel and con- 

 glomerate, but the formation as a whole is argillaceous and carries 

 a large proportion of the clays of this county. Its sands, like those 

 of the Patuxent formation, are water-bearing. The strike of the 

 formation is from northeast to southwest, and the beds dip to the 

 southeast at the rate of about 40 feet per mile. The thickness of the 

 formation has been estimated at Turkey Point to be about 360 feet 

 and at Chesapeake City as 200 feet. 



The Baltimore and Ohio Railroad cut at Foys Hill exposes the 

 following section: 



Formation. Feet. 



Patapsco. Buff sands, water-bearing at base 25 



Dense, variegated clays 10-30 



Another good section is found in the deep cut of the Philadelphia, 

 "Wilmington and Baltimore Railroad, one and one-eighth miles east 

 of Principio Creek. 



