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Ketton and Stamford
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Ketton Geology Trail - Phil Findlay
A party of 18 met Carol at 10.30 a.m. in the Geology Trail car park at Ketton. The sunny day that had been forecast did not materialise but it stayed dry (and warmer than later in the day when the group visited Stamford!)
From the A1, the Castle Cement Works signpost the location of Ketton to the West. In Ketton, Pit Lane provides access from the A6121 to the Cement Works. The Lane continues past the Cement Works to the right and then the Ketton Geology Trail is signposted on the left. The cement works reflect one of the current uses of the local rocks; the Ketton Architectural Stone and Masonry Workshops, just before the turn for the Geology Trail car park, indicate another. The Geology Trail itself (497558E 305713N) is sited in a disused quarry, parts of which were last worked as long ago as the 1930s. All of the rocks are from the Jurassic Period. The complete trail is visible from the car park. Hard hats were needed for the small overhangs at localities 2, 3 and 4 and although there are concrete steps, stout footwear was needed for the muddier tracks and for investigating the clays at Locality 2.
Locality 1. Here we were straight into hand lens activity examining the ooliths of the uppermost beds of the yellow Lincolnshire Limestone. The rock consisted almost totally of even-grained ooliths with no visible shell debris. Concentric growth rings were very clear in split ooliths at the surface. The fact that such limestone can be cut in any direction to form different shapes led to its description as 'Freestone'. As well as being used for buildings in local communities, Ketton Limestone was used extensively in Cambridge. The first major use there was for the building of the east range of Clare College (1638-41). Most of Downing College and the screen wall of King's College on King's Parade are built of Ketton Limestone. In fact, Ketton was then the dominant building stone in Cambridge for two centuries before the Jurassic Oolite from Ancaster took over from the middle of the nineteenth century.
The top of the Lincolnshire Limestone marks an unconformity. The uplift of the sea floor about 165 million years ago led to the erosion of the missing sedimentary beds as well as colonisation by land plants. There is a suggestion that the circular, brown patterns on the top surface of the limestone outcrop could be fossil tree parts.
A look upwards towards Locality 3 revealed long, horizontal cracks and gaps in the grass covered slope: small scale mass movement in the clays of the Rutland Formation.
Locality 2. This location consists of a steep but easily climbed slope of the coloured clays of the Rutland Formation. A brown-red clay bed and, higher up, a green clay bed were very clear. The complete sequence involves a series of flooding surfaces with sediments in-between, rising from shelly deeper water material through shallower and brackish water sediments to reed beds before the next flooding surface brings a return to the deeper water shelly sediments. Inspection of the surfaces by the group revealed mussels, probably Modiolus, sea urchins and turreted gastropods. Fossil roots of the reed beds were not identified but these were very clear in the large blocks assembled at Locality 5 that we examined more carefully as we returned to the car park later. Early Yellow Coltsfoot (Tussilago farfara) on the less disturbed edges of the slope added to the colours of the clay beds. From these edges you could see a fault running from the top right of the face to the bottom left. This is part of a more widespread network of faults caused by slipping downwards towards the River WeIland valley. The much deeper Upper Lias Clay beds underneath the massive limestone beds are the weakness allowing this slipping.
Localities 3 and 4.Exposures of Blisworth Limestone at Localities 3 and 4 both provided lots of shell fragments to examine. In particular, there were many oyster shells (Liostrea). Hard hats were needed especially at Locality 4 where you felt the presence of the overhang each time you stood up after examining specimens below eye level! In the areas shaded by trees between Locality 3 and 4 there were lots of Hart's Tongue Ferns (Lingua cervina), a plant that thrives in the limy soil.
On returning to the car park, the group had the opportunity to examine a range of fossils and minerals that Harry Briggs had brought along. The fronds of the crinoids from Charmouth and the Mammoth's tooth with enamel still visible were especially striking. Our thanks go to Harry for this opportunity to see and handle such a variety of fossils and minerals.
Much of the geological information in this report has been drawn from a Guide Sheet to the Ketton Geology Trail written by Alan Dawn. Thanks also go to English Nature, the Geologists' Association and Castle Cement for providing funding for the publication of the leaflet and Castle Cement for carrying out much of the work on the car park, paths and concrete steps for' the trail. Above all, thanks from the group go to Carol Hagan for initiating and organising an enjoyable geological day.
Stamford Museum Town trail – Sarah Ashmore
Stamford has old roots, being one of five boroughs of the' Danelaw' and a Medieval Market Town. It is a very appealing town, with more stone buildings than I have ever seen in one place. The buildings range from magnificent churches and halls to quaint cottages and roads from wide streets to narrow passages. It is a bustling place on a Sunday with a long street market, a brass band (singing "we love Stamford"), free parking and numerous cafes and tea shops. I shall not relate all the places on the route, just certain ones.
Our group of around 16 met outside Stamford Museum, which was built of Stamford Freestone. This got its name because it can be worked in any direction. Herbert Harts across the road was also the same stone. Walking along Broad Street, we came to the War Memorial. The retaining wall behind was made of red sandstone, with distinct cross-bedded marking in them. A notable feature along the way was the use of different materials for the roads and paths. Outside the Crown Hotel there were reddy pink cobbles which were diorite. On Barn Hill, the cobbles were grey granite from Portugal. York stone was laid flat as slabs (such as on the town hall steps) or cut as kerb stones and laid end on. The divisions between the layers could easily be seen. It made a very good match with the stone colour. In many places pebbles have been set in paths to provide a durable surface.
We moved on to All Saints Church and witnessed the heavy weathering on the North Porch. We were eager to see the font, but couldn't as a service was in progress. In the Churchyard there was a distinct Swithland slate gravestone.
Later we viewed the Larvikite on the front skirt of Woolworths. It looked nearly black, with large feldspar crystals in it. I looked closer and saw one side of a crystal go into extinction, then the other. This brought geology to life for me. On Saint Pauls Street we saw many buildings with Collyweston slate roofs. This is a very strong material. The large slates were placed near the eaves and reduced in size as they got closer to the ridge. Sheer weight and some nails held the slates on safely.
Further on we viewed the chimney house (No.10 Saint Georges Street). This was a mixture of building styles and stones and severe renovations. It would have been a quaint cottage originally.
Later we encountered the Stamford Hotel (now an indoor shopping complex). It is a very magnificent building, with massive stone pillars on the front. Different stones are used for different jobs, according to their durability. If you see this beautiful building, stand back and look up, to see a stone lady on the top. It looks like she is throwing her arms up in horror at someones bad joke. I would love to have rented a room in that hotel in its hey day. Opposite the Stamford Freestone built Town Hall, is a Norman arch in the wall. This was once an entrance to a house. It now leads to an alley way. I closed my eyes and imagined all the cars gone and Normans driving horses and carts up and down. A well dressed Norman opened the door and asked us in for a drink. A lot better than the modern rush of traffic.
We finished on the Town Bridge looking up and down the beautiful River WeIland, it would have been solid with boats in the old days. We made our farewells on a stimulating, exciting and interesting day. Back to the car with my friends Helen and Keith. One last photo of a beautiful bank of daffodils. If you get the chance to do the walk you won't regret it. Thanks to everyone there who were so kind and helpful.
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