"At 1, a series of compressed folds has been worn down to a plain, the surface of which is formed by the edges of the nearly vertical strata. At 2 an anticline has been reduced to a valley, and at 3 a syncline is left standing as a ridge made up of concave strata like a pile of platters. The ridges at 4 are projections of hard strata above the more easily eroded ones on either side." -Dryer, 1901

Appalachian Mountains

"At 1, a series of compressed folds has been worn down to a plain, the surface of which is formed by…