This Ordovician fossiliferous limestone is so named because it is packed with numerous brachiopods Heterorthis alternata, as in the lower inset picture. It was collected by the side of the river in the Onny valley, near Craven arms in Shropshire.
This specimen of fossil rich sandstone was collected from Hillend in Shropshire. It is from the Pentamerus beds, which are in the upper Llandovery series of the Silurian period. The location is on the S.E margin of the long Mynd. This rock has earned the "nickname" of Government rock, alluding to the characteristic arrows of the pentamerus oblongus which are reflected in prison uniforms of many years ago.
This specimen was collected from the same location as Mineral rich sedimentary rock-1 It differs only in the amoumt of quartz and silica. in specimen 1 the major component was quartz, with just a little calcite. In this specimen the major component is calcite with only a small amount of quartz. The calcite has the appearance of a flow deposit, and as in the other specimen,when viewed fron the side there are traces of the original layers of sediment.
This specimen is probably the most interesting rock that I have collected It was collected in the vicinity of the hill top wind farm near Llandinam. just a couple of miles away.A zig-zag road was excavated in the hillside to create access to the summit of the hill, and this specimen was collected from the newly exposed cutting, at an elevation of about 500m. asl. It appears to be sedimentary rock that has been infiltrated by hydrothermal mineral rich fluid. About 90% of the original sediment has been replaced by silica in the form of tiny quartz crystals The other 10% is sediment which has been silicified There are traces of the original layers of sediment, and also some calcite deposits. A second specimen from the same location Is mostly calcite, with some quartz and is illustrated in the the next article.
This specimen of Coralline crag was collected from Thorpeness beach, on the Suffolk coast. The occasion was in September 2021, on a field trip led by Tim Holt Wilson, who's comprehensive guide to the geology of the Suffolk coast, I have included in the photograph. Coralline crag is a sandy fossiliferous marine limestone, which is not exposed at this location. Pieces of this rock are washed up on the beach from an offshore formation. A thorough search of the beach will provide specimens with more obvious pieces of bryozoan fossils.