The Triassic Rocks of Nottingham, Sunday 13^th July 2003

  The day turned out to be very hot indeed and the 14 participants who took part in this trip took advantage of shade whenever it was available. Keith Ambrose of the British Geological Survey was our leader for the day. Keith had very kindly borrowed a mini-bus from the B.G.S. so that we did not have to worry about following each other in our cars around Nottingham. When all had arrived at the meeting place on the Nottingham University campus (and the car park did take some finding) the party set off down the hill to the first locality.

  We made for an exposure on the northern bank of the lake in the university grounds where 7 m. of the Nottingham Castle Sandstone are seen. This formation was previously called the “Bunter Pebble Beds” as it contains pebbles of quartzite eroded from Variscan mountains. The sandstone represents the deposits of a major river with many low sand bars, which were constantly prograding downstream with the current. The sand migration shows up as large-scale cross bedding, which is very nicely seen at this exposure.

   A short drive away across the campus near the computing centre the party examined a 6 m. section of the Lenton Sandstone Formation. The stone is a deep red colour with mottling of yellowy brown patches. The red colour is caused by iron oxide, which, with a small amount of clay, weakly holds the sand grains together. The group examined the crumbly sandstone and found it to be silky when rubbed between the fingers.

   Leaving the university campus we headed for Bramcote to see the famous Hemlock Stone. Unfortunately we had picked a weekend when road works necessitated a long detour. When we did arrive we had the site to ourselves, which was helpful from the photographic point of view, because it was our intention to duplicate as closely as possible an 1883 photograph held in the New Walk Museum’s collections showing the LLPS visiting the site in the heyday of Queen Victoria. As we ascended the hill, a few significant differences were apparent between the ‘then and now’. One was railings to keep out the vandals and another was the sad proliferation of graffiti (although a close study of the 1883 photo, featured elsewhere on this website, reveals that graffitti engravers were busy even in Victorian times). Finally, the base of the Stone had been buried beneath a quantity of soil, presumably to protect it from collapse.

The Geology Section, 2003 style, at the Hemlock Stone

   Some discussion took place as to the origins of this isolated stack of barite-cemented sandstone. The consensus of the group was that it had been left during quarrying long ago. Our Victorian antecedents had a few theories too, and believed that it might have been an ancient sea stack, but that seems implausible. Weathering had revealed nicely developed cross-bedding in the sandstone. Many photographs were taken of the group in front of the Stone in a position as close to the original photograph as the railings would allow, and one is shown here, taken by Joe Sowerby.

   The last of the exposures we visited was on the other side of Nottingham, at Colwick Park. After walking through pleasant parkland we came to an old quarry face overgrown with trees. The face exposes 7 m. of the upper part of the Sneinton Formation and 2 m. of the overlying Radcliffe Formation. The fine-grained sandstone beds of the Sneinton Formation are 2 - 5 cm thick and many betray their shallow-water origin with ripple marks and shrinkage cracks.

   We ended the day by thanking Keith for his informative leadership and for giving the group such a good insight into the area during Triassic times.

 Dennis Gamble