Abstract

Comparison of planar and trough cross-stratification directions from several fluvial formations and modern ephemeral streams shows significant differences in the distribution pattern of the two types of cross-stratification. Trough cross-stratification of all sizes is unimodal, coincident with the channel direction, and has a small degree of scatter. In contrast, planar cross-stratification generally is either unimodal with wide scatter or bimodal with subequal modes at 50 degrees to 60 degrees to both sides of the channel direction. Trough cross-stratification is thus a reliable and precise paleocurrent indicator, requiring relatively few measurements to reconstruct the true channel direction. In contrast, planar cross-stratification must be used with caution, and a relatively large number of measurements are needed to reconstruct the paleocurrent system.

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