Maryland Geological Survey G1 



east of the Fall-line varies from 50 to 90 feet in the mile, the average 

 being about 60 feet in the mile. 



The rate of dips in feet per mile at varions points is: 



FEET FEET FEET 



Burtonsville 75 Perry Hall 66 Battle Swamp 73 



Laurel 65 Loreley 100 Throdors 100 



Ilchester Hill 68 North of Joppa. . .60-80 Bay View 90 



Relay 200 Abingdon 100 Egg Hill 80 



Catonsville 114 Harford Furnace... 70 Cherry Hill 60 



House of Refuge 75 Carsins 100 Barksdale 45 



Baltimore 80-90 Aberdeen 109 Grays Hill 50 



Towson 66 Aldino 100 Iron Hill 50 



Cub Hill 58 Webster 100 Chestnut Hill, Del. . 50 



The altitude of the Patuxent beds in the Lutherville area previously 

 mentioned is anomalous, for besides lying at a lower level than the de- 

 posits farther to the seaward the dip is slightly to the northwestward. 



From the above facts it is apparent that the deposits near the Fall- 

 line have been subjected to greater deformation than the beds farther 

 eastward, still in no instance is there any certain evidence of actual 

 faulting along this line, although the high angle of dip at Eelay, the 

 elevated position of the beds at Catonsville, and the abnormal altitude 

 of the strata at Lutherville, all point to unusual structural conditions 

 that may find their explanation in the faulting of the strata. 



The maximum thickness of the Patuxent formation in Maryland is 

 not less than 350 feet and may considerably exceed that amount. In 

 the well boring at Indian Head it has been penetrated for a thickness 

 of 353 feet without reaching the crystalline floor. In northern Virginia, 

 at Alexandria, the brewery well shows 380 feet of Patuxent materials. 

 Toward the landward margin of the Patuxent formation less thicknesses 

 are found, the deposits frequently not exceeding 150 to 200 feet. A 

 similar thinning of the formation occurs seaward, as shown by the 

 deeper well borings in eastern Maryland and Virginia. 



Stratigeaphic and Structural Relations. — The Patuxent forma- 

 tion, as the basal formation of the Coastal Plain, rests directly on the 

 crystalline rocks of the tilted and submerged margin of the Piedmont 

 Plateau. This surface more or less eroded and trenched before the 



