If a landmass of whatever structure and large area be upheaved unequally to considerable altitudes in its interior area and if it then stand still for an indefinitely long period, it will be eventually degraded to a plain. In order to avoid the necessity of assuming so indefinitely long a period of still-stand, and in order at the same time to detain attention upon the gently undulating surface that such a region will have before it is worn down to a plain, the term peneplain was invented some thirty years ago. As no one, I believe, proposes to call the surface of ultimate degradation a “plane,” I see no sufficient reason for calling the penultimate surface a “peneplane,” as some have proposed; the original spelling, peneplain, is preferred.
When the term was first proposed it was vaguely defined; and it has recently come to my . . .