500 W. B. Clark — Brandy wine Formation of the 



demonstrated that the Lafayette as defined by Hilgard and 

 described in detail by McGee comprised the weathered surface 

 materials of various Cretaceous and Tertiary formations. 

 Shattnck* in his study of the surficial formations of Maryland 

 limited the term Lafayette to the highest of the terrace forma- 

 tions, the formation to which the author now gives the name 

 of Brandy wine. 



The terms Appomattox and Lafayette as originally employed 

 in the Middle Atlantic Coastal Plain embraced much more, 

 therefore, than it is proposed to include under the name 

 Brandywine formation, and likewise, the diagnosis of that for- 

 mation is based on different physiographic conceptions from 

 those used by McGee and Darton. Furthermore, the term 

 Lafayette as origiually employed in Mississippi was based on a 

 misconception of the stratigraphy of the region. The use, 

 therefore, of either the term Appomattox or Lafayette for any 

 formational unit is impracticable. 



Areal outline. — The Brandywine formation covers an exten- 

 sive area in the southern Maryland peninsula, reaching from 

 the eastern boundary of the District of Columbia to the 

 northern line of St. Mary's County with numerous outliers 

 both to the north and to the south of these lines. It attains a 

 maximum width, therefore, from northwest to southeast of 

 nearly 40 miles. From this region it narrows both to the 

 northeastward and to the south westward, being confined largely 

 to the landward margin of the Coastal Plain. It reaches to 

 the northward through the central counties of Maryland into 

 Delaware and Pennsylvania, while to the southward it has 

 been traced in the interstream areas and along the landward 

 border of the Coastal Plain through Virginia into the Caro- 

 linas. Less is known of the details of its areal distribution 

 in Virginia than in Maryland and the states which lie to the 

 north of it. 



Altitude and character of landward boundary.— The alti- 

 tude of the landward boundary reaches 400 feet in the outliers 

 in the western part of the District of -Columbia, 4S6 feet at 

 Burtonville in Montgomery County, 508 feet at Catonsville, 

 Baltimore County, 480 feet at Loch Raven, Baltimore County, 

 and 470 feet at Woodlawn, Cecil County. No one of these 

 more western outliers covers more than a few square miles of 

 area. Each is extensively eroded and isolated from the main 

 body of the formation farther seaward. All are found in 

 interstream positions, their coarse gravel content protecting 

 them from destruction. 



*Shattuck, G. B. : Pliocene and PleistoceDe, Maryland Geol. Survey, 291 

 pp., 75 pis., 10 figs., 1906. 



