The ‘summer’ theme for this month’s Keeper’s Corner called to mind sunny days walking along beaches collecting seashells.
One such shell you might find is a tower shell, Turritella communis (pictured below, left). Here in Bucks we are a long way from the seaside but that doesn’t mean that you can’t find seashells. It just means that they will be of the fossilised kind. The fossil shown below (right) is known as Portland screw, Aptyxiella portlandica, its name coming partly from its shape and partly because it is found in Portland Limestone. The Portland Limestone is found from Dorset through to Bucks and formed around 149 million years ago as the prehistoric seas that covered Bucks were becoming shallower and dry land was starting to appear. If you could travel back to this time you might find yourself on a recently emerged prehistoric beach somewhere between Haddenham and Aylesbury looking for Portland screw shells. But remember, they would look more like the tower shell as the fossil versions we find today only preserve the internal mould, the original shell having dissolved away millions of years ago. Also, remember to look out for dinosaurs creeping up behind you.
You can find a selection of other local fossil seashells on display in the Museum’s Discover Bucks Geology gallery.
