60 THE PHYSIOGRAPHY OF SI. MARY's COUNTY 



line. It enters St. Mary's County near Oaks and runs southward to Point 

 Lookout, coincident witli the direction of the Three Notch Eoad. From 

 Oaks to Hermanville its general trend is southeast, although it departs 

 first on one side and then on the other from this general direction. From 

 Hermanville it turns abruptly to the southeast and continues this direc- 

 tion to Point Lookout. Throughout its entire course the divide is 

 situated northeast or east of the line passing down the center of the 

 county. 



The most important tributaries of tlie Patuxent and Chesapeake waters 

 are Indian, Trent Hall, Persimmon, Horse Landing, Cat, Cole, St. John, 

 and Cuckold creeks, which enter the Patuxent; and St. Jerome and 

 Deep creeks, which enter Chesapeake Bay. Most of the streams enter- 

 ing the Potomac are much larger and are converted into estuaries through- 

 out their lower courses. They are the Chaptico, St. Clement, Mcintosh, 

 Herring, St. George, and Smith creeks, and St. Mary's Eiver. 



As would be expected from the position of the divide, the streams 

 which empty into Chesapeake Bay and the Patuxent Eiver are very 

 much shorter than those which find their way into the Potomac Eiver. 

 They also flow through deep, steep-sided gorges. Those which enter 

 the Potomac Eiver have much longer courses and, as a rule, wider valleys 

 with more gentle slopes. This difference between the streams flowing 

 north and those flowing south is probably in part due to the more active 

 erosion of the Patuxent Eiver and Chesapeake Bay. It will be remem- 

 bered also that where these river courses are shorter and steeper, there 

 the lowest terrace has suffered most from erosion. Along the Bay shore 

 similar conditions held before the second terrace was deposited as are 

 now found along the Calvert Clifi's in Calvert County, for at the inner 

 margin of this latest terrace there is a steep escarpment which was cut 

 in precisely the same manner as Calvert Cliffs are being cut to-day. 

 The pushing back of the shore-line toward the divide so as to throw 

 the whole out of symmetry was doubtless accomplished while this latest 

 terrace was being deposited. 



