Environmental Sensitivity of Submicroscopic Surface Textures on Quartz Sand Grains--A Statistical Evaluation

Abstract

A statistical evaluation of the occurrence of selected surface textures on quartz sand grains from eolian and subaqueous environments was made to determine their environmental sensitivity. Samples collected at Padre Island, Texas, and the adjacent inland dune fields were used to identify the limits of sensitivity on a local scale ( i.e. , beach, dune, etc.). In comparing means and standard deviations, only the lagoonal facies was found to be distinctive. It could be identified easily by the abundance of chemically etched, oriented triangular-shaped patterns. The other features characteristic of subaqueous or eolian processes are more or less equally distributed throughout the coastal area. Analysis of scatter plots and linear regression revealed weak trends in which subaqueous features are replaced by eolian features moving inland from the beach. Comparison of statistics for the samples from the Texas coastal region with statistics for samples from four interior deserts suggests that if over half of the grains in a sample have chemically etched, oriented triangular-shaped patterns or mechanically formed V-shaped pits and straight or slightly curved grooves and scratches, then a coastal province might be deduced. Irregular or polygonal cracks were present on over half of the desert grains examined and were much less abundant on the grains from the coastal region. None of the other six features examined were statistically distinctive for environmental determinations.