Recording, conserving and promoting the landscape and rocks of the Sheffield region

SAGT News

Geological Walks for GeoWeek - May 12th & 13th 2018 - Report

St Bees Sandstonek

Which way is up? (St Paul's Parade)

SAGT planned two "field" visits for the new national venture, Geoweek 2018. A geological walkabout was arranged for 12th May, to look at the building stones in Sheffield City Centre and to try to elucidate the story of Britain's position on the globe in the past. On the day, only two visitors turned up - a 6th Form Geology student and her mum, although we also got some funny looks from passers-by. The student said that the tour gave very useful revision for A Level, and soon found herself deciding which blocks of stone had been inserted into the buildings the wrong way up, using evidence such as cross-bedding. Her mum, an ecologist, accepted that the geology controls what grows or lives on top of it, and also found the morning of value. The alabaster tombstone of the Earl of Shaftesbury, outside the back of the Cathedral, should be examined for more and more growing on top of it as it rapidly weathers!

Burbage geowalk

So where did they quarry this millstone from?

The second excursion, to the southern end of the Burbage Valley on 13th, was attended by 6 people, in glorious sunshine. Clambering over the fallen blocks of gritstone on the way up to the two deep quarries on the eastern edge of the valley revealed a wide range of features, ranging from sedimentary structures and possible plant imprint fossils, to the results of man-made activity. As might be expected, there were the marks of quarrying, including drill holes for the "plug and feathers" technique of splitting blocks and some amazing lines of chisel marks where somebody optimistically had begun to mark out the division of an absolutely huge mass of gritstone. Many of the blocks were pock-marked by bullet holes or mortar blasts from WW2 when the valley was used for live-firing training. The group discussed the evidence of periglacial processes and searched (in vain) for marine fossils in the shales next to the river, so had to be content with "one we found here before" from the leader's rucksack!

So, two enjoyable trips, but we need to widen the publicity if we do this again next year.

Don Gorge Walk - 11 May 2018

Don Gorge Walk

Don Gorge Walk

SAGT has again linked up with the Don Catchment Rivers Trust for a second year, to guide a geology and landscape walk through the Don Gorge. Twenty intrepid walkers turned up, and the weather and the gorge did not disappoint. Over three hours we rambled at a steady pace for about three kilometres along the gorge looking at the Permian limestones, the landscape development and drainage of the area, finishing up with a stroll down to the limekilns, and the site of the old Levit Haag village. As ever, the local knowledge of the participants, some of whom remembered the village, contributed a great deal to the event.

Sandstone data & visit to Sheffield - 8 May 2018

Measuring sandstone using XRF

An MSc student, Keegan Burrows and his tutor, Dr Ralf Halama, from Keele University, carried out an initial survey into some of the building stones of the Sheffield region on 8th May. They are using an XRF technique which enables rapid measurements to be made of the ratios between the elements which make up the minerals in the rock. It is hoped that this might throw some light on the source areas from which the sediments were derived during the Carboniferous Period. It may also be possible to define which major sandstone units have provided some of our local building stones - in most cases the documentary evidence for their origins has been lost. The photo shows Keegan using the XRF gear on an exposure of the Greenmoor Rock, which was formerly of great importance as a building stone and a source of grindstones, and is still worked near Huddersfield.

Yorkshire Geology Day - posted 24 April 2018

General cemetery

SAGT took part in the Yorkshire Geology Day celebrations at Caphouse Mining Museum on April 21st. Mums & Dads brought their children (and their rock and fossil collections to be identified) and met Geology Trust members from across Yorkshire. There were geo-activities, experiments to get children thinking, lots of useful ideas for day trips out to see rock places, as well as guided underground trips, lots to see in the museum, and even fossil biscuits. Make a note in your diary for 2019: the second Saturday in April and come along.

Sheffield: the city that rocks - posted 13 April 2018

General cemetery

General cemetery

Geography teachers attending the 2018 Geographical Association conference, held in Sheffield, used the SAGT Sheffield Building Stones Trail to discuss how to use rocks in town centres for pupils to see examples of a variety of rocks and learn about different rock types, their properties and how they link in the rock cycle. They even worked out how you can see evidence of plate tectonics in the rocks of Sheffield town centre.

Led by SAGT member Duncan Hawley (in blue in first photo), the teachers went on a field walk from the Peace Gardens down Fargate to Campo Lane at the back of the Cathedral where they were tasked with finding examples of igneous, sedimentary, metamorphic and fake rocks, finally ending with excellent examples of stone weathering - 'flaking', 'scaling' and 'granular disintegration' - caused by repeated wetting and drying of the stone leading to growth of salt crystals just under the surface that lever the rock apart.

Charter Square - posted 2 March 2018

Charter Square general view

Charter Square - general view of the new stonework
neon river

A highly metamorphosed xenolith in the dark Chinese "granite". The 1p coin is 2cm diameter
neon river

A cross-bedded sandstone from Hall Dale Quarry

Sheffield Council's Landscape Architects have continued their thoughtful use of natural stone with the new work being installed in Charter Square. The general view shows the paving in a range of pale-coloured Chinese granites, the bench seats and one of the sandstone "monoliths". These large blocks are of Namurian age and come from the Hall Dale Quarry, near Darley Dale, and some show cross-bedding and ironstone nodules. The seats are made from pink and buff Stanton Moor Sandstone, with the legs of Stoke Hall Sandstone from Grindleford. A dark "granite" from China is used for the kerbstones and many of these display superb xenoliths of older rock fragments, highly metamorphosed by the heat of the granitic magma. Some slabs have huge white feldspar crystals, which cooled from the magma at a slower rate than the rest of the rock and so had more time in which to crystallise.
Further work is planned in Charter Square, so keep your eyes peeled!

Match it! - posted 1 January 2018

city infirmary city infirmary stone block
SAGT is endeavouring to match some well-known Sheffield buildings to the sources of their building stone. Here is one in which we are confident, where fieldwork and archive research have come together.
The former Sheffield Royal Infirmary, 1793, was built from sandstones of the Loxley Edge Rock. Small quarries and worked blocks of stone occur in the woodland below the scarp face of Loxley Edge (at Grid Ref SK3105 9058; purple scale bar is 25cm).
Loxley tooled block

Best minor fold? - posted 1 January 2018

monoclinal fold monoclinal fold

Is this the best minor fold in Sheffield? (About 100m downstream of Forge Dam at Grid Ref SK305850). The tape shows one metre. The fold axis runs roughly parallel to the trend of the valley of the Porter Brook, so could the fold be the result of earth movements or "valley bulging"? Discuss!

SAGT News Archives 2017