back eddies are created down stream of local currents and affect landfall. normally the down current side of any geologic protrusion collects the highest density of landfall—current running south to north: look on the north side of any point of land—current running north to south: find the highest landfall on the south side of geologic protrusions (point of land). if there is high density of landfall you will see significant microplastic at the surface. it is only necessary to lift the top quarter-inch sand surface onto the tool.