on the ‘convex’, I noticed there were surprisingly few.After the stones, the bones and the oyster shells, the next most noticeable without really trying are the fragments of pottery ..Two other common items that can do with a little background are the oyster shells and the animal bones.Oysters have been native to the Thames Estuary since the beginnings of time apparently, and it was only relatively recently that they ceased to be a major food source especially for the poor.There are so many fragments, not just because for more than 300 years they were sold filled and routinely chucked when smoked, but also because the hundreds of pipe-makers working along the foreshore would likely ditch their kiln leftovers or rejects into the Thames.
Clay pipe bowls can be dated with some certainty according to their shape, size and decoration, and with even more accuracy if they feature a maker’s-mark on the ‘heel’, the protrusion under the bowl.
Most locations have either patches or whole banks of shingle, some interspersed with areas of sand, others with areas of mud.
Regarding those ‘stones’, I had, as it were, questioned their authenticity earlier.
So the abundance of their discarded shells along the London Thames is more than accounted for by that fact, whether or not the river itself supports them or how much they’ve been specially farmed here in the past. the city’s unusable leftovers tipped into the Thames for hundreds of years.
As far as I know the common ingredients are sheep, cow, goat, pig and poultry, perhaps with a portion of horse and even a smattering of boar, especially in the Greenwich area where the Tudor royal palace used to be. that the concentration of bones in the Greenwich area relates either to 200 years of Tudor/Stuart feasting or to the 19th century Foreign Cattle Market at neighbouring Deptford .. I suspect it has more to do with the river bends and the way these influence where the tidal currents deposit different things.
you’ll have to go to either a museum or an antiquities dealer for those ..