An Analysis of Cross-Lamination the Coconino Sandstone

This paper calls atention to the advantages of the use of the stereographic polar net for representation of cross-bed attitudes and describes a mode of analysis for the same based on the consideration of each attitude as a vector quantity. The analysis yields a weighted average direction of dip and a numerically expressed measure of the consistency in direction of the individual dips. The latter is shown to embody the significance of the statistical "standard deviation." To a map-symbol representing the vector resultant direction and the consistency an arc expressing the range in direction of the individual readings is added. The remainder of the paper illustrates the analysis by a study of the Coconino sandstone in northern Arizona. A brief review of its literature and the evidence of its probable Aeolian origin is given. It is concluded that the transporting currents responsible had a southerly direction, except the in district south of the Little Colorado River, where they swung sharply to the east. The evidence from the possibly contemporaneous De Chelly and Cedar Mesa sandstones is noted and discussed.