SECTION'S IX THE POTOMAC RIVER VALLEY. 131 



Y. Section of ilie Nomini Cliffs of the Potomac River, seven miles helow 



mouth of Pope Creel:. 



Feet 

 Pleistocene Reddish-yellow and gray sands, coarse sands, 



and gravel ; indurated corrugated iron 

 stone near base 20 



Miocene. Calvert Greenish-gray more or less sandy clay 45 



Greenish-gray argillaceous sand slightly in- 

 durated. Contains mammalian bones. . . 1 



Greenish-gray argillaceous sand 22 



Fossil band in greenish-gray clay 2 



Greenish-gray sandy clay 11 



Fossil band of greenish-gray argillaceous 

 sand. Fossils especially numerous near 



base ; Melina abundant 4 



Greenish-gray sandy clay containing a band 

 of fossils near base; contains diatoms.... 20 



Total 125 



Throughout the entire length of the ISTomini Cliffs the beds seem to be 

 almost horizontal. No single bed has been traced throughout the entire 

 cliff section but layers have been traced for a mile or more in different places. 

 The materials in general in sections II and V are about the same. There 

 are certain undulations in the beds but no noticeable dip. In both cases the 

 upper half of the Miocene is almost without fossils. The lower half has 

 several prominent fossil bands at the centre. These continue toward the 

 east but become less prominent in that direction. Diatoms are abundant 

 in the lower 25 or 30 feet throughout the entire length of the cliffs but are 

 less noticeable in the eastern portion. The fossil laj^er near the base of 

 section IV is perhaps the same as the fossil band 20 to 24 feet above base in 

 section V, Between section V and the extreme east end of the cliffs the beds 

 again descend a few feet. 



The fossils for the most part, except a few oysters, barnacles, and many 

 pectens are soft and fragile. Some of the fossil layers in the Nomini 

 Cliffs outcrop for a distance of a mile or more but none extends the entire 

 length of the cliffs. There are very few fossils, if any, in section III. A 

 few were noted in section II. The best place for collecting is between 

 section IV and section V. It is probable that nearly all the beds exposed 

 in the Nomini Cliffs, if perfectly fresh, would be dark green in color. In 

 most places, however, more or less weathering has taken place so that they 

 appear greenish-gray, light green, or even almost white. 



