ABSTRACT

Analysis of an abandoned meander preserved in toto in the Harold sandstone of the Breathitt Formation allows 1) accurate determination of primary input variables in paleomorphology calculations, namely channel bankfull width, depth, and cross-sectional area, and 2) evaluation of established methodologies. Bankfull depth is equal to the thickness of the entire fining upward cycle and to the thickness of point bar accretion surfaces, within measurement error. Channel width is equal to 1.4 times the horizontal extent of point bar accretion surfaces, slightly less than the 1.5 value commonly used. Channel cross-sectional shape is closely approximated by a trapezoid.

The continuity equation, Q = A V is used to calculate an average bankfull discharge, Q. Bankfull cross-sectional area, A, is accurately reconstructed from an abandoned meander channel and V is calculated from Middleton's (1976) ''criterion for suspension". Average flow velocity, V, estimated from this method is similar to flow velocity estimated from initiation of sediment motion curves and graphic relationships among grain size, bedforms and flow velocity. Close agreement exists among values of Q calculated from the continuity equation and several independent regression equations developed by Schumm (1972) for modern, fluvial environments. Estimates of stream length and drainage basin size are consistent with paleogeographic reconstructions of the southern Appalachians during middle ennsylvanian time.

When compared to measured outcrop parameters empirical equations which employ M, the sediment load parameter, are consistently better estimators of paleomorphology and paleohydrology than empirical equations without M, provided that diagenesis does not obscure the original percent of silt-clay in the channel alluvium.