The V-valley of youth is thus changed by planation to a flat-floored valley with flaring sides which gradually become subdued by the weather to gentle slopes.
"The Elements of Geology"
William Harmon Norton
When will they begin anew the work of lateral planation?
"The Elements of Geology"
William Harmon Norton
After this planation was complete, a subsidence occurred; the whole area became the bed of an inland sea, and upon the planed-down granite, the debris that formed the Algonkian strata was washed.
"The-Grand-Canyon-of-Arizona-how-to-see-it"
James, George Wharton