The five discrete ash layers found at Perito Moreno, of which four are primary airfall deposits, are believed to have originated from Mt. Hudson volcano. The geochemical analyses, which are currently in progress, will provide major element compositions of tephra in each layer. Grain size data were obtained by wet sieving each tephra layer using nine different sieve sizes. Statistical measurements for grain size data for each tephra level were obtained through calculations instead of graphical methods. Level N5 is poorly sorted, symmetrically distributed and the mean and mode fall within the silt and sand size-range, respectively.
Calculations reveal a coarse, strongly skewed distribution, with a moderate peak.
Level N4 is moderately well sorted, symmetrically distributed and has a mean and mode that are within the slit and sand-size range, respectively. The distribution is coarse and strongly skewed. Level N3 is moderately well sorted, and has a fine-grained mode and mean. The distribution is fine and strongly skewed, and has low kurtosis. Level N2 is poorly sorted and has a mode and mean in the silt-size range.