meaning of, [51].
Underfolding, of earth’s shell, [437].
Underground water, [180].
Undertow, [236].
Unstable erosion remnants, in “driftless area”, [300].
Upham, Warren, cited, [325], [327], [339], [344], [350].
Upland, fretted, [372], [373];
maturely dissected, [170];
mature, unfavorable to commercial development, [171];