INTRODUCTION 



AND 



GENERAL STRATIGRAPHIC RELATIONS 



BY 



WILLIAM BULLOCK CLARK 



Introduction. 



Geologists recognize three great natural provinces in the Atlantic 

 border region, which are commonly designated the Coastal Plain, the 

 Piedmont Plateau, and the Appalachian Eegion. Each of these dis- 

 tricts possesses distinctive physiographic and geologic characters that 

 easily separate it from the others. 



The oldest and most complicated district is the Piedmont Plateau, 

 which is composed largely of ancient schists and gneisses of unknown 

 age, part of which are certainly pre-Cambrian. 



The Appalachian Eegion Avhich adjoins the Piedmont Plateau on 

 the west is mainly composed of Paleozoic sediments which throughout 

 much of the district have been deformed into a series of folds that 

 gradually decrease in intensity westward. 



The Coastal Plain, the youngest of the three districts, is composed 

 of a series of largely unconsolidated and horizontal sediments that rep- 

 resent a nearly complete sequence of deposits from the Middle Mesozoic 

 to the present. 



Each of these provinces can be traced from Pennsylvania and New 

 Jersey southward to the Gulf States and is approximately parallel 

 with the axis of the great mountain uplift of the Appalachian moun- 

 tain system which from early geological times has marked the eastern 

 border of the continent. It is evident therefore that a knowledge of 

 Maryland geology cannot be complete without a careful comparison of 



