TEXTURAL ANALYSIS OF BEACH AND DUNE SEDIMENTS FROM THE LAKE ERIE SHORELINE IN NORTHWESTERN PENNSYLVANIA

The grain size distribution of sediment is a fundamental physical property of texture, affecting many other properties, such as porosity, bulk density, and permeability. In addition, the classification of sediments relies entirely on grain size distribution data, and therefore determining grain size is a necessary skill for geologists and environmental scientists. Grain size can be measured using a variety of different methods, including using visual inspection, sieving, and via laser diffraction analysis. Each of the methods provides insights into sediment textural properties, however differences in the methods of analysis potentially yield unique suites of information. The goal of this project was to measure and analyze the textural properties (grain size, sorting, and grain shape) and composition of sediment samples from the Lake Erie coastal zone in northwest Pennsylvania using visual inspection, sieving, and laser diffraction. Sediment samples were collected from beach and dune environments at Presque Isle State Park and Erie Bluffs State Park. Samples were first analyzed using all three analysis methods to establish baseline textural datasets. Percentile grain size values from the sieving and laser diffraction analyses were used to calculate grain statistical parameters including the graphic mean, standard deviation or sorting, and skewness. Next, representative beach and dune samples were measured repeatedly (a minimum of 10 times) with a Microtrac SYNC laser diffraction system to evaluate the degree of measurement reproducibility. Comparison between run percentile grain size values and the calculated grain size statistical parameters will be used to assess reproducibility. Lastly, the textural analysis data from select beach and dune samples measured via sieving and laser diffraction will be used to evaluate the similarity of results between these methods, both of which require different sediment masses for analysis, and rely on different calculation techniques (mass vs. volume percent), respectively. Results from this project will produce baseline textural datasets for beach and dune systems along the Lake Erie coastal zone and the analyses will yield insights into potential methods biases for sieving vs. laser diffraction techniques.