80 THE PLIOCENE AND PLEISTOCENE DEPOSITS OF MARYLAND 



them. Just across the Patuxent river at Marriott Hill, and on the highest 

 hills of Elk Neck at the head of the Bay, there are other scattered patches 

 of Lafayette gravels which also rest on Coastal Plain deposits. Along the 

 eastern slope of the Piedmont Plateau from Virginia across Maryland, 

 Delaware, and Pennsylvania, there is a long line of outliers which rest 

 either on beds of Potomac or directly on the crystallized rocks of the 

 Piedmont. The most important of these are located in the western part 

 of the District of Columbia, near Burtonville, at Catonsville, near Loch- 

 raven, near Stockton, and on the Piedmont area of Cecil county near 

 Woocllawn. There are also other smaller patches scattered throughout 

 the area. ISTo deposits referable to the Lafayette formation have been 

 recognized on the Eastern Shore south of Elk river. It will be seen by 

 referring to the geological map (Plate I), on which the various surfi- 

 cial formations are represented, that the distribution of the Lafayette is 

 very nearly parallel to the Western Shore of Chesapeake Bay. In west- 

 ern Maryland five miles north of Frederick, there is a deposit of loose 

 gravel which cannot be correlated with any other deposit in that part of 

 the State. It occurs at an elevation of about 500 feet and probably, as 

 Keith has suggested, should be referred to the Lafayette. 



Structure and Thickness. — The fragmentary character of the La- 

 fayette formation makes it a little difficult to arrive at a satisfactory 

 conclusion regarding its structure. On the Piedmont Plateau it was 

 deposited on an uneven surface, and erosion has now reduced the 

 formation to isolated areas. If the various elevations at which these 

 outliers rest are compared in an endeavor to determine the dip, there is 

 danger of drawing an erroneous conclusion, for an area where the 

 Lafayette rested on an ancient prominence may be compared with one 

 where it was deposited in a hollow. Over the Coastal Plain the basal 

 portions of the formation are not visible throughout. They can be 

 traced in the vicinity of Washington, but as the formation passes south- 

 ward toward Charlotte Hall, the succeeding Sunderland terrace laps up 

 about the lower portions of the Lafayette formation and conceal its 

 contact with the older formations. As the Lafayette formation is thin 

 and varies in thickness within narrow limits, a nearer approximation to 



