Two lines of evidence suggest that this cache represents elements of a single net or a group of similar sized fishing nets—1) the context where they were found and 2) the general uniformity of individual net sinker’s size, shape and weight. Mr. Kunkle stated that “….the cache lay within a pocket of dark grayish soil about a foot in diameter that appeared pasty and organic….”. The dark soil matrix encapsulating the cache might indicate that the net sinkers were buried still attached to a casting net or other fishing device that subsequently rotted away over time.
The figure below presents the length/width/thickness measurements in millimeters of the pebble sinker cache (N=80). A rather consistent pattern is noted in the width at notch measurements taken at the narrowest point of each sinker. Statistically speaking, notch width measurements show a range of only 5.9 mm at one standard deviation and just over a centimeter within the 2-Sigma range. This means that roughly 68% of the net sinkers in this cache have a notch width ranging between 36.4-24.6 mm (~3.5-2.5 cm) and about 95% of the net sinkers in this cache have a notch width ranging between 42-19 mm (4.2-1.9 cm), with an average width of 30.5 mm (~3 cm).
Could this tight range of notch widths correlate to the spacing distance between knots in the fishing net to which they were attached ? If so, this would suggest that the ropes of the net were spaced about 3 cm2 apart or at roughly 1.25 square inch intervals—a net that would most likely be used to catch large fish.
Total weight of the cache is 2,715.3 grams - a dead weight of pebbles that after notched and attached to a net, might be more useful for bottom dragging (i.e. capturing foods such as mussels, eels, crayfish or other bottom feeding critters.
We thank Mr. Kunkle for donating the net sinker cache to the State Museum of Pennsylvania where it is now curated and openly available for future study.
For more information, visit PAarchaeology.state.pa.us or the Hall of Anthropology and Archaeology at The State Museum of Pennsylvania .