Malvern Building Stone Walk

Malvern building stone walk Wednesday 25 May 2016 Led by Kate Andrew, EHT The walk started at Great Malvern Station, outside the booking hall (by water trough) (Grid Reference SO 78168 45759). This is location 1 on the map below. Kate explained that the walk followed a trail for one of the new Earth Heritage "Geology and Walking trail guides". This has not yet been published, but is expected to be called "Explore Malvern - Spouts and Springs". The total length is abound 3km if one were to finish at the start point. 1. Malvern Railway Station We examined the water trough by the Great Malvern railway station entrance. This had been installed in 1880 to supply drinking water for the horses providing transport to and from the station. Kate explained the types of building stones used for the trough, and then we looked at the wall itself. The trough had alternative red and cream stones above the spout. The red stones are a soft Triassic sandstone which is probably the local Bromsgrove sandstone. The cream stones are oolitic limestone - Bath Stone. The two supports for the trough are a green sandstone - Cradley Stone. We then looked at the stones in the surrounding wall which are constructed from random pieces of Malvern stone rubble. The majority of the pieces were diorite, but the odd piece of red granite and basalt. Some of the diorite had an external covering of the greed epidote. We also found a sample of Barite - Barium Sulphate (top left in picture). This white mineral is precipitated in hot hydrothermal veins created in faults in the Malvern rocks. Barite is mostly found in Tank Quarry. 2. Orthodontist Centre - 9 Imperial Road This is a fine nineteenth century building showing off various building stones. The majority is built from pale green Cradley Stone. This is lower Devonian in age and was quarried five miles away. Cradley Stone is used extensively for house building in Malvern. Around the edges of the rough Cradley Stone other smoother stones are used, a style known as rustification. The window surrounds are a honey coloured oolitic limestone from the Cotswolds. On either side of the door there are two red sandstone pilasters made from a Triassic sandstone. 3. Thornbury House - 16 Avenue Road Thornbury House is again built using Cradley Stone. It also has a similar rustification style, but we were told that this is somewhat artificial. The same Cradley Stone is used for both the walls and the window surrounds, they are just dressed differently. Of interest is the extension added to the right if the main house. This was build using Forest of Dean sandstone which is Carboniferous from the Pennant Sandstone Formation. The Cradley Stone quarry stopped working in the mid twentieth century so was unavailable for use. There is a good colour match however, the Forest of Dean sandstone having a slightly grey colouration. Kate told us that the two stones will weather differently as well. The Forest of Dean sandstone has silica cementing the sand grains together whilst Cradley stone uses calcite. 4 - No 12 Avenue Road Another nice residential property, the walls constructed using Malvern stone. The windows are a bit more interesting, with oolitic Limestone for the window edges and what was thought to be Cradley Stone above the windows. 5 - Elmslie House - 8 Avenue Road Another house constructed on Malvern stone. We looked at the colour difference between the main house and the extension. The gable end of the main house is built from very red (acidic) Malvern Stone and the extension from a darker, more basic stone. We discussed the difference between these two terms, acidic and basic. It comes down to the chemistry of the magma. The paler, acidic rocks have more quartz and feldspar in them, the basic rocks lack these. John Payne enlightened us as to how the term originated. It was initially thought, incorrectly, that the silica in the rocks came from a chemical reaction involving silicic acid. We looked at some of the rocks in the pavement walls. As well as some basalt and epidote we found examples of slickensides. One good example, which is easy for others to find, is in the fourth cap rock to the right of the gateway (on Avenue Road). Slickensides are a smooth polished surface on a rock caused by the frictional movement of rocks along two sides of a fault. 6 - Priory House At the entrance to Priory House we examined the pillars. These looked as if they were originally Cradley Sandstone (light green), but there had been an amount of repair using Hollington Stone from Derbyshire (red). The entrance pillar to Priory House Priory House was originally build by Dr. Gulley, one of the founders of Malvern's water cure in Victorian times. The site and gardens were bought by the Council in 1927 and became the Priory Gardens and Council Offices. The buildings are built with Cradley Stone and oolitic Bath Stone. We examined the repair work to the original stonework, some good and some not so. A consistent problem would appear to be water ingress into the sandstone which is then trapped by the impermeable pointing, causing erosion over time. On either side of the main entrance there are two red granite pillars. Not local, this granite consists of large pink feldspar crystals ringed with quartz. We found a xenolith, a dark piece of country rock which had fallen into the magma whilst the granite was crystallizing. Granite pillars at the entrance to Priory House - plus xenolith 7 - Swan Pool spring At the northern end of Swan Pool there is a spring which supplies the water for it. The spring line is probably the junction where the sandstone abuts the Malvern granite (covered with glacial head). Like most of the springs in Malvern it is probably not a good idea to drink the water without boiling, only the water from the Malvhina is safe as it is filtered. 8 - Jacob fountain inside Malvern Theatres This fountain replaces the original one installed in the Winter Gardens in 1923 (which was a lot more pleasing to the eye in the editor's opinion). It commemorated Dr. Jacob, local physician and leader of the council. The green paving around the base is made from Westmorland slate, a volcanic ash from the Borrowdale series. It is slightly metamorphic. The basin itself is Carrara marble from Italy. Jacob fountain and the base 9 - South Wall of Malvern Priory From Grange Road we viewed the southern wall of Malvern Priory. We could see a mismatch of repair work with many different colours of stone. The stone used was what was to hand at the time over many centuries. Kate picked out Bromsgrove Sandstone, Hollington Stone, Cradley Stone and oolitic limestone from the Cotswolds. 10 - Park View - 33 Abbey Road On the approach to Park View we looked at a series of cobble setts used for paving. Kate thought these were Clee Hill Dhustone, a Carboniferous dolerite. Setts from here tend to be square and very black. Note that the rectangular items between the setts are normal bricks. 11 - Ward Jackson's fountain The pipe in the arch in this wall was once a prolific spring, but is now blocked off. It was built in 1868 by Major Ward Jackson on land donated by Miss Mary Palmer. The pure water supply was used for the good of the town, unlike those who used the Malvern water for their commercial gain. 12 - The Wilson Memorial The current Wilson Memorial replaces the previous memorial and fountain which were demolished in 1948. It is to commemorate Dr. James Wilson who established the water cure in Malvern. Unveiled in 2015, this new memorial is carved from a block of Carboniferous Pennant sandstone from the Forest of Dean. The memorial itself shows faint cross bedding and some brown liesegang rings. The rings are caused by iron staining. The paving slabs around the memorial are of the same material and show ripple marks and flecks of organic coal. 13 - Warwick Court - opposite 33 Abbey Road Firstly we looks at Park View. This is now flats, but was built by Dr. Gully who used it for his water cure premises between 1845 and 1867. At that time it was known as the Establishment. When the water cure had its day it became the County Hotel, and then an MoD hostel. Across the road from Park View we looked at Warwick Court, and John Payne told us something about its underlying geology. Recently, during the construction of new houses adjacent to the main Wells Road, a lovely exposure of Triassic Bromsgrove Sandstone was uncovered. As well as the Sandstone there were same glacial deposits thought to be material washed down into a side channel next to the Malvernian rocks of the hills. There was not enough exposure to be definitive, and it is now completely covered up. John explained that the Malvern town centre is where it is because there is a long stretch of Bromsgrove Sandstone, providing a stable and flat platform for the main road and the houses around it. 14 - Abbey Hotel The Abbey Hotel is built from dark diorite and granite Malvern Stone with Cradley Stone dressings and Bath Stone balustrade to the entrance. In places, the Cradley Stone has been replaced with repairs of Forest of Dean Pennant sandstone. 15 - Priory Gatehouse Priory Gatehouse - south elevation Forest of Dean Pennant sandstone has been used to repair the window mullions which were originally of a softer green sandstone (as pointed at by Kate).

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