Just before my holiday I had an enjoyable time leading a group of home schoolers on a fossil hunt in a disused clay pit near Peterborough. The sedimentary rocks from which we collected belong to the lower part of the Middle Jurassic Oxford Clay Formation. The trip gave us the opportunity to think about the formation of mudstones, sedimentary rocks dominated by silt- and clay-sized particles. Mudstones are usually thought to have been deposited by the very slow settling of fine dispersed grains in quiet water conditions. But new research is causing geologists to reconsider the conditions under which fine-grained sediments are deposited. In fact, flume experiments and field observations show that muds can be deposited at current velocities that are sufficient to transport and deposit sand.
Certainly the extraordinary abundance of the fossils in the Oxford Clay seems to be consistent with rapid rates of sedimentation. Everyone on the trip was able to take home a fine collection of ammonites, belemnites, Gryphaea oysters and the occasional brachiopod! It was very gratifying to see the enthusiasm of the families that took part and to receive some lovely ‘thank you’ cards from the youngsters afterwards. I’m always happy to consider similar opportunities, so do let me know if you think your group – homeschoolers or otherwise – would be interested in an educational trip of this kind. Just email email@example.com.