130 PHYSIOGRAPHY AND GEOLOGY OF THE COASTAL PLAIN PROVINCE. 



III. Section of the Noniini Cliffs of the Potomac River, four and one-half 



miles below mouth of Pope Creek 



Feet 

 Pleistocene Yellowish sands and clays, about 45-50 



Miocene. Calvert Greenish-gray clays, sandy clays, and sands, di- 



atomaceous in lower 25 or 30 feet 65-70 



Total 120 



IV. Section of the Nomini Cliffs of the Potomac River, six miles below 



mouth of Pope Creel-. 



Feet 

 Pleistocene Reddish loam grading down into reddish-yellow 



and gray sand, with a band of large pebbles 

 and cobbles at base 35 



Miocene. Calvert Greenish-gray, more or less sandy, laminated 



clay, plastic and tough in upper 8 feet, 



without fossils 55 



Indurated layer of greenish-gray sandstone, 

 rusty on surface where weathered. Con- 

 tains casts of pectens, etc. This forms a 

 prominent layer which can be traced for 



a mile or more along the cliff 2 



Greenish-gray slightly argillaceous sand full 

 of fossils, — pectens, etc., — ^most of which 



are in a soft friable condition 10 



Greenish -gray more or less argillaceous sand 

 and sandy clay with several bands contain- 

 ing fossils; diatoms were observed in lower 

 12 feet 33 



Total 135 



This section is very similar to section II althoiTgli much more fossilifer- 

 ous in the lower 45 feet. In the above section there is a band of fossils 3 to 

 5 feet above base, one 12 to 16 feet above base, and one 33 to 43 feet above 

 base. 



About one-third of a mile east of section IV the prominent indurated 

 layer indicated in that section at height of 45 feet is at least 60 feet above 

 base, showing that it rises to the east. This means either that the beds 

 beneath rise also or that they gradually thicken. The latter appears to be 

 more probable. Beyond this point to the east the indurated layer loses its 

 characteristics and can no longer be traced. 



