Im posting this as potomac river but this is from a rare land site in PG county several miles from the river.When the storm drains and ponds are dug out the top layer of the aquia formation is exposed.THe huge mass of shells make it hard to pick out teeth.After looking around a few minutes , I did find a few small and med sand tigers. At least they are not river worn.Im keeping my eye out for a perfect giant otodus as the teeth weather out over the summer.