The three subdivisions which McGee has clearly shown to be equally characteristic of both the geology and topography of the middle Atlantic slope* are admirably contrasted by the cross-section made of them by the state of Maryland. The land area of the state may be set down in round numbers as 10,000 square miles. By a similar approximation, the western 2,000 square miles of this territory may be assigned to the Appalachian zone; the central 3,000 to the Piedmont region; and the eastern 5,000, which surround Chesapeake bay, to the coastal plain.
In the west the Paleozoic strata are thrown into broad and gentle undulations, which increase steadily in abruptness as we move eastward. Finally a certain amount of recrystallization accompanies the more intense disturbance, and positive evidence of the age of the oldest and most easterly strata seems to have been obliterated. Between the last Paleozoic beds . . .