Heavy rains and storms in Dorset: Collecting fossils

Tony and Anna Gill (UK) The best time to look for fossils in Dorset is after heavy rain and winter storms. These conditions make the cliffs unstable and collapse. High winds produce rough seas, which wash the mud away, leaving the nodules that contain the fossils exposed on the beach. The beginning of November 2005 saw a period of heavy rain and strong winds. This stormy weather continued for several days and on 5 November gale force 10 winds, before a high tide, exposing new material (Fig. 1). Fig. 1. A large landslip, approximately four hundred metres east of Charmouth, contains most of the best fossil horizons. This slip is illustrated with the sea crashing into it (Fig. 2). The large stones in the picture below do not contain any fossils. If they did, they would not be there. The best place to look for smaller fossils is around these large stones. Some of the pyrite ammonites found here can be up to 25cm to 30cm in diameter. Fig. 2. The storm crashing against the cliffs at Charmouth. The flat stones, which are from the Obtusum Shales, sometimes contain the ammonite Asteroceras Planicosta and usually the smaller ammonites Promicroceras Planicosta (Fig. 3). Fig. 3. Charmouth was the seabed in Jurassic times, some 195 million years ago. The football shaped and sized, Stellare Nodules, when broken, contain calcite crystals. Occasionally though, an ammonite can be found inside the larger ones. These ammonites can be up to 50cm across, but unfortunately, most … Read More

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