I took my son for a walk over the wilderness between Bengeo and Waterford at the weekend. He found a couple of nice fossils -- various extinct marine invertebrate species from the Jurassic period. I collected a number of similar specimens from the same excavation during my own childhood. Now, my son continues this family tradition. Eventually, I plan to buy him an Indiana Jones style hat and challenge him to find the Ark of the Covenant and the Holy Grail.
He dug up a whole Belemnite (skeleton from what may be an ancestor of modern squid or cuttlefish species) and several shells from a Gryphea dilatata or "Jurassic oyster" (a bivalve shell, perhaps an ancestor of modern oysters). Both marine creatures disappeared in the Jurassic-Cretaceous mass extinction period, so the fossils are presumably at least 65 million years old and might be 200 million years old. The Hertford area was beneath the ocean between 65m and 80m years ago. We were excavating intermediate layers of Middle Glacial gravel, but this doesn't necessarily date the sample because any geological stratification was disrupted by glacial activity around Waterford marsh during the Glacial Period and Ice Age from 10k to 2m years ago.
I've always been fascinated by the geology and archaeology of the glacial sea bed north of London. where I spent my childhood. There's a fine line between prehistoric archology and geology.
28 October 2015