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The Norfolk Coast, 29-30 September 2001 Leader Bob Markham |
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The joint field excursion with the Essex Group of the Geologist's Association was attended by eleven people, six of whom were ERMS members. Our leader was Bob Markham formerly Geologist at the Ipswich Museum. Our base was Cromer where we stayed for two nights. On Saturday morning we all met up at West Runton car park and walked in a westerly direction. Campanian period, Upper Chalk, about 75 million years old was seen on the foreshore in a very fragmented condition. Large flint circles rested on the chalk with holes in some of the flints. A sponge coated in limonite was seen together with several broken belemnites of Belemnitella mucronata. Above the chalk was a few small hard blocks of the 1.5 million year old Weyborne Crag laid down in marine conditions during a cold phase. The bivalves Macoma balthica and Mya truncata were seen in it, but difficult to collect. Reptilian mososaur teeth and even jaws have been found in the chalk in the past. A few terebratulid and rhynchonellid brachiopods were also found in the chalk. We walked about half a mile to where a twenty feet high block of boulder clay was resting on the beach. We returned to the carpark for lunch looking at the cliffs formed during the Anglian glaciation, 440,000 years ago. The laminated chalky boulder clay was very contorted with folds, thrusts and sand basins in it. It contained a few Norwegian erratics. After lunch we walked eastwards to look at the well known Cromer Forest Bed where a 'Straight Tusked Elephant' was found in the 1990's and is now in Norwich Museum. The 750,000 year old deposit rests on the Weyborne Crag. Some large blocks of Norwegian Larvakite (Note 1) protected the base of the site. The black organic Forest bed contained small pieces of wood, with small mammal teeth found in sieved material. Ron Flack found a piece of elephant femur and Chris Beaugeard found part of a deer antler. We later moved on to Weyborne where we saw a good exposure of the crag in a cliff section there. Left hand side Neptunea gastropod shells could be found 1.5 million years old. We collected sandy deposits from the bed for sieving and the bivalves Artica islandica, Mya and Mycoma could be seen. On Sunday morning we went east of Cromer to Overstrand. After a good walk we saw two forest exposures of Upper Chalk. This was the youngest chalk seen in the British Isles, Lower Maastrichtian in age, 70 - 75 million years old. The zonal belmnite Belemnella lanceolata was seen as well as a few specimens of the echinoid Echinocorys scutata. Chris Beaugeard found a fine large specimen and also a good one in flint. Flint columnal specimens of the small crinoid Bourgueticrinus brydonei were also collected from the chalk. The boulder clay in the cliff contained large sections of chalk folded over and distorted. I found a large squashed specimen of Echincorys scutata at the base of it. We finished the field trip at lunch time and thanked our leader for an excellent weekend's geology with some fossiling and good weather thrown in. David Turner David has promised me a look at the pictures when they come back from developing. So do take another look at this page from time to time. The intention is to update it with pictures when available! David is our Field Trips Secretary and is very experienced at what can be found and seen on field trips. If any other member would like to pen an article either about a trip or meeting do have ago. Another perspective from either the experienced or novice is never a waste. We all can learn from one another Many thanks for the article Dave. Keep that pen and camera at the ready. More please! RC 05/10/2001 Supplementary Notes (below) by RC. Note 1. Larvakite (I think the spelling may be Larvikite, I will check this out with David and others more knowledgeable than myself later): A coarse grained rock, mainly of large feldspar crystals. When cut and polished as a flat slab, the play of light incident with some of the feldspars reflect a burst of colour, (blues in this case), which is a composite of natural and interference colours. The effect is more properly known as the Schiller effect. The stone is often used ornamentally, as a facing stone. Sometimes seen on the fronts or foyers of business premises like Banks and Building Societies. I think it is more than likely that members will see some examples on the next field trip which is the "Building Stones Walk around Colchester" on the 21 October. I believe the Norwegian Larvikite was dumped at this location during the late 1980's early 1990's as part of an attempt against stemming coastal erosion! Anyhow, a couple of small bits turned up in the lapidary workshop at this time believed to be from this source. I think it was more likely to have been pieces leftover from a cash machine heist with a JCB. (RC 05/10/2001) (Back to Text) |
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Pictures of collected fossils. Previous Trips: Thrislington |