MARYLAND GEOLOGICAL SURVEY 69 



the eastern border of this county the waves of Chesapeake Bay have 

 cut an almost unbroken exposure rising nearly 100 feet in height and 

 extending from Chesapeake Beach to Drum Point, a distance of about 

 30 miles. 



Arcal Distribution. 



The Calvert formation which lies at the base of the Chesapeake Group 

 in Maryland crosses the state from northeast to southwest. On the 

 Eastern Shore it is found in the southeastern corner of Kent County, 

 throughout almost the entire extent of Queen Anne's County and the 

 northern portions of Talbot and Caroline counties. 



On the Western Shore the Calvert formation is found extensively 

 developed in Anne Arundel, Prince George's, Charles, Calvert, and St. 

 Mary's counties. It appears as a long line of outcrop extending from 

 the hills near the head of South Eiver estuary to a place on the Calvert 

 Cliffs near Point of Eocks. With this breadth, it extends across south- 

 ern Maryland from Chesapeake Bay to the Potomac Eiver, and is devel- 

 oped along the latter stream from the hills north of Washington to 

 the mouth of the Wicomico. 



Notwithstanding this great development, the Calvert formation is 

 seldom met with on the surface of the country but must be sought in 

 the cliffs of the larger estuaries and in the walls of stream gorges. 

 As on the Eastern Shore so on the Western, the Calvert formation is 

 covered by younger formations. 



The distribution of the Calvert formation in this county is shown on 

 the geological map which accompanies this report. It is found through- 

 out the northern portion of the region as far south as a line connecting 

 Eosl3'n Creek on the Patuxent with the lower portions of St. Clement 

 Creek, in the Potomac Valley. Throughout this region the Calvert 

 formation is so extensively covered over by the sand and gravels of the 

 formations belonging to the Columbia Group that it is nowhere found 

 along the divides but occurs in the valley walls of important streams. 

 To the north in neighboring regions the Calvert formation lies uncon- 

 formably on the eroded surface of the Xanjemoy formation. This rchi- 



