OUTLINE OF CENOZOIC HISTORY OF A PORTION OF 

 THE MIDDLE ATLANTIC SLOPE. 1 



In the spring of 1891, I published a preliminary account of 

 the Mesozoic and Cenozoic formations of eastern Virginia and 

 Maryland, in which there was given a brief resume of the his- 

 tory. 2 Studies have been continued in the region, and much new 

 information has been acquired, especially regarding the rela- 

 tions and history of the younger formations. Notice of the 

 results of these studies was given at the meetings of the Geologi- 

 cal Society of America, in December, 1892, and August, 1893. 

 In this paper, there is presented a brief summary of the principal 

 features, but further details and a more extended discussion, will 

 appear later in a memoir now in course of preparation. 



The middle Atlantic slope extends with fairly regular decliv- 

 ity from the Appalachian range to the ocean. It comprises two 

 provinces, the Piedmont and the Coastal plain. The former, 

 which lies to the westward, is a high undulating plateau carved 

 in greater part in crystalline rocks ; the latter slopes to the 

 ocean, and is underlain by unconsolidated deposits ranging 

 from Cretaceous to Pleistocene in age. The Piedmont belt is 

 traversed by rivers which flow in gorges, and the minor water 

 ways run in deep rocky valleys. The slope to the eastward is 

 gentle and the province merges into the Coastal plain in a zone 

 of moderate width, in which, to the northward, there is increased 

 declivity. The surface of the Coastal plain comprises wide areas 

 of plateau to the southward and rolling hills to the northward, 

 which attain maximum elevations from two hundred to three 

 hundred feet. It is bordered on the eastward by low terrace 

 plains, and traversed by wide depressions, which contain terraces 

 of various heights. The gorges of the rivers of the Piedmont 



1 Published by permission of the Director of the U. S. Geological Survey. 

 2 Geol. Soc. Am., Bull., Vol. II., pp. 431-451 ; Plate 10. 



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