Cynically, with how much trash there is around rivers you're likely to be fossilized within a strata chock full of traces of our civilization. Non-cynically, I

Cynically, with how much trash there is around rivers you're likely to be fossilized within a strata chock full of traces of our civilization. Non-cynically, I would recommend having a stone abacus crafted if you wish to be buried this way - effectively mineralize the relic manually and don't leave its fossilization up to chance. You could also try encasing some objects into amber or resin and scattering them around your final resting place.