| Popis: |
Two well exposed outcrops of the Homewood Sandstone in western Pennsylvania provide an excellent opportunity to document and compare local dip azimuth variability of tabular and trough types of cross-bedding. Tabular-shaped cross-beds occur at one locality; trough-shaped units at the other. All measures of scatter--consistency ratio, standard deviation, and spread--are appreciably greater for the randomly measured foreset dip azimuths of trough cross-bedding. If readings along trough axes only are considered, the scatter is greatly reduced and is comparable to that displayed by tabular cross-bedding foresets. At each locality the current direction is uniform both stratigraphically and areally. Thus, the markedly different distributions of foreset azimuths for these two cross-bedding types is related to an inherent property of the sedimentary structure, the curvature of foresets within individual units. |
