62 THE PHYSIOGRAPHY OF CALVERT COUNTY • 



An outline of the topographic history will now be given under the follow- 

 ing four stages, beginning with the oldest : 



1. The Sunderland Stage. 



2. The Wicomico Stage. 



3. The Talbot Stage. 



4. The Eecent Stage. 



THE SUNDERLAND STAGE. 



During the Sunderland stage, the oldest of the three terraces which 

 were described above was made. This terrace is known as the Sunder- 

 land terrace and the materials which compose it constitute the Sunderland 

 formation. Before the Sunderland stage was initiated, it is probable 

 that the entire surface of Calvert County was covered with a deposit of 

 reddish-brown clay, sand, and gravel, which is developed extensively 

 over the Coastal Plain of Maryland, Virginia, the Carolinas, and south- 

 ward, and described under the name of the Lafayette formation. As no 

 remnant of this deposit is at the present time known to exist in Calvert 

 County, it follows that if it ever did extend over this region, it has since 

 been removed by erosion. It is not necessary to discuss this question 

 further than to say that on the top of Marriott Hill, a short distance 

 beyond the northern border of Calvert County, an outlier of the Lafayette 

 formation occurs, while around its flanks the Sunderland terrace, with 

 its characteristic deposits, is found developed. Both the topographic 

 and geologic relations of the Lafayette and Sunderland formations in 

 this place indicate that the hill existed as an island whose shores were 

 washed by the Sunderland sea and around whose border the Sunderland 

 formation was deposited. Again in St. Mary's County to the southeast 

 of Calvert Countj^, an extensive mantle of Lafayette was eroded by the 

 Sunderland sea which cut a scarp-line against it precisely as the waves 

 are now cutting a sea cliff against the present shore. The Sunderland 

 formation was laid down at the base of the scarp-line by the Sunderland 

 sea at the same time it was cutting back the edge of the Lafayette forma- 

 tion and producing the scarp.^ 



= This subject will be found discussed at length in the Report on the 

 Pliocene and Pleistocene Deposits of Maryland, Md. Geol. Surv., 1906. 



