Raritan. 



Patapsco . 



Maryland Geological Survei 85 



XXII. Section of ivell at East Washington Heights, near Overlook Inn, D. C. 

 Pliocene ( ?) Feet. 



Lafayette . . . . Loam and gravel 15 



Miocene. 



Calvert Fine yellow ocherous clay ("marlite") closely 



jointed with occasional small leaf imprints, grad- 

 ing into mealy sand, iron crusts at summit 40 



Cretaceous. 



("Dark colored, somewhat glauconitic sand 15 



Magothy. . . \ Light drab laminated sandy clay, at times carbon- 

 ic aceous 8 



'Loose buff, brown, yellow, gray and white sugary 

 sands, more or less cross-bedded and indurated, 



with light drab leaf -bearing clay 25 



Massive and stratified bluish-drab clay, at times lig- 

 nitic and pyritiferous and occasionally blotched 



with red ocher 10 



White clay in local lenses. Massive and stratified 

 light-colored and drab clay, interbedded 10 



Dense variegated and drab, jointed clay, grading at 

 times into sand, lower portion more or less covered 



by flanking of Pleistocene and " wash " 100 + 



Red and drab clay with ferruginous sandstone largely 



covered by flanking of Pleistocene and " wash". . . . 70+ 

 Patuxent ... .Beginning 20 feet below tide. Cross-bedded arkosic 



sand, with interbedded clay, estimated 440 



Crystallines At level below tide of 460 feet. 



Total 733 



INTERPRETATION OP THE UPPER CRETACEOUS 

 DEPOSITS 



The Upper Cretaceous formations indicate the presence of a great 

 variety of geological conditions during their deposition. During the 

 epoch in which the Earitan beds were being laid down, conditions were 

 more nearly like those of preceding Lower Cretaceous than later iti Upper 

 Cretaceous time. A considerable interval must have elapsed, however, 

 after the deposition of the Patapsco formation during which the Lower 

 Cretaceous formations were materially eroded, since the Raritan strata 

 overlie the older beds with a clearly defined erosional unconformity. 

 Furthermore, a very great change in plant life had taken place in the 

 interval between the Patapsco and Earitan epochs. 



The Raritan beds are more generally arenaceous than the preceding 

 Patapsco formation and contain but little arkose as compared with the 



