“Salt flats” of north-central Texas are local erosional flood plains (hydrologic) formed in an area of youthful topography. Development initially depends on establishment of a local base level by a wet impermeable stratigraphic lens overlain by soft, dry silts, sands and clays. Ground water flowing laterally along the bottom and top of the resistant lens escapes by springs and seeps where the lens is intersected by stream valleys. This causes undercutting and slumping of overlying soft, dry materials which are removed from the valley by sheet wash during wet periods. Thus, the valley is widened laterally but the intermittent stream is unable to entrench below the base level established by the perennially wet sediments. The term “channel seepage flat” is suggested because development does not depend on corrasion by lateral stream action.