Geo-Amble 14th August 2017

HERE is a geology map of the area and notes on the formations

We parked near Ham Bridge at the entrance to the driveway leading to Ham Mill and Ham Farm.  Along the way to the small quarry that was our destination we noted the very steep hillside we assumed cut into by the River Teme and obviously of a more substantial make up than the flat river valley.  According to the geology map this is Raglan Mudstone territory, the lumps of rock we found along the way being a type of fine sandstone, often found within the softer mudstones.  The geology map of the area does not however show these sandstones hereabouts so seems to be somewhat in error.  I stopped the group to show a distinct hollow way, leading up the steep, grassy hillside away from the river and a local crossing point.  I have always taken this to be a drover’s trail created by centuries of passing herds. Further on a very disturbed area, shown on the map as a quarry, the question being for what?  Possibly mudstone for bricks as no rocks visible (although the Building Stones database states it is St Maughans, that is wrong). Scattered about in the grass around here we discovered several giant puffballs and the group volunteered that I should take home the largest and eat it myself.  Writing this from my hospital bed I can tell you that fried in butter with garlic and olive oil it was like eating marshmallow, not unpleasant with quality bacon and a fried egg, but not a repast I am likely with much enthusiasm, to re-eat. As we approached Ham Farm we noted buildings, some very ripe for refurbishment, made from cut stone, with brick infill and timber frames.  Through the farmyard on the right of way, it was a short walk up to the small sandstone quarry and the source of these stones we were sure.

Although the Building Stones database again states that this sandstone is St Maughans formation from the Devonian period it cannot be, as it is far below the Bishops Frome nodular limestone which itself lies under the St Maughans. I sought direction from a noted geologist and she tells me it is definitely in the Raglan sequence, being the sandstone referred to above and obviously in sufficient quantity for it to have been used in the local farm buildings.

The quarry face showed clear signs of bedding at odds with the mainly horizontal layers.  GEO AMBLE 14AUG17 (7)First thoughts were that this is an example of ‘cross’ bedding and I for one have never really grasped what that is all about. For those of you who like me struggle with simple things here are some notes. If sediments are laid down without disturbance (I am thinking underwater for this) then they will form a smooth layer over the underwater ground surface.  Stops and starts in the deposition and/or changes in particle size, will show as joints (see below).  If water flows across this submerged layer, then the particles will tend to be moved along dependent on the speed of the current and the particle size. We have all seen ripples in beach sand and these form under flow conditions. Exactly why they form is not fully understood (I am pleased to report, HERE is more information) but they do. As ripples develop, particles are driven up the shallow slope that faces upstream, reach the top then tumble down the other side, which is steeper. This occurs whether water or air (wind) is the driving force and in air the ripples are usually much larger.

Because the particles vary in size and density, given their origin from (possibly many) different types of rocks upstream, they do form distinct, albeit thin, layers.  If the ripples are preserved by subsequent deluges bringing  more material down and burying them, then eventually rock is formed and the ripples are retained and visible if the rock is cut into.  HERE is an animation that might help.

The other process in operation within, especially, braided rivers, is where channels move around in the bed of the river, cutting through existing deposits (themselves ‘bedded’) and creating new ones on the inside of bends and so on as flow rates vary. You can imagine that this can leave a very confused set of beds built up over time as illustrated below.  It is possible to see these paleo-channels in rock exposures, certainly at the Nubbins and here too I reckon.

braided river 3d levels

Sedimentary deposits act as a geological tape recorder (I remember those); they record the activity of the local environment and in the quarry we looked at this would have been a river.  If there is a change in the process, for example increased flow (and therefore carrying energy) putting down bigger particles, then the layers will show this, sometimes very subtly.  The layers are separated by bedding planes and these tell us that deposition stopped. In effect this is a gap in the record that could last from minutes to thousands of years. Moderate i.e. thick beds, such as we saw at the quarry in the lower sections, tell us that deposition continued in the same way for a very long time with little disturbance. Higher up, and quite abruptly, the beds became much thinner indicating a more disturbed environment.  What could this have been?  Climate change leading to increased flow?  End of the Silurian and start of the Devonian–continents colliding?  Ideas on a post card please. A more lengthy explanation is to be found HERE.

Downton Gorge 18th May 2017

Simon Cooter, Senior Reserves Manager, Natural England based at the Stiperstones Nature reserve, patiently guided 15 of us on a morning tour of part of the River Teme’s Downton Gorge, upstream of Ludlow. Simon had clearly, long ago mastered the skills of leading from the back, of allowing a linger-long crowd of rockers, birders and plant experts to take their time in this unique place, whilst adding his own sage comments with dashes of poetry as appropriate.  I think that we were quite pleased to hear from Simon that we had not been the slowest group he had led around.  That honour belongs, he said, to the Society of Conchologists, but they would be wouldn’t they?   The weather was fine, what an improvement on yesterday’s non-stop deluge, the vegetation at its spring best, not too verdant to cover over the many rock exposures. We entered near Bringewood House, walking upstream some considerable way beyond Castle bridge. The geology map clearly shows a dramatic change in rock types.

Downton gorge, through which the Teme rapidly flows was at Bringewood, the site of very early iron smelting and forging (from the 1500s) taken over and hugely expanded by the Knight family a couple of centuries later.  The steep descent of the river bed provided plenty of water power to drive the bellows and hammers, whilst the woodlands were given over to the production of charcoal for smelting. It must, in those days have presented a blasted site, with nary a foothold for nature in the area of the works. Now that industry has ceased, only a few stone buildings and several weirs remain to hint at previous activity.  Existing too, are walks and rides constructed by the Richards’ Knight (there were several) subscribers to the Picturesque movement.  We were led into grottoes and caves, on to high promontories by way of slippy steps and ledge like walkways along precipitous hillsides, to be met with sudden openings of dramatic river and woodland vistas.

The route of the Teme has changed over the millennia.  It used to form part of the headwaters of the River Lugg, flowing past Aymestrey, but the last ice age (Devensian), its advances, retreats and final melting changed all that.  It is conjectured that ice melt, blocked on other routes, overflowed the low point en-route East (towards present day Ludlow) and with the difference in height beyond was able to cut deep into the softer shales, developing a gorge back upstream to the flat lands near Leintwardine, site of prehistoric Lake Wigmore. This reversal in the direction of flow, is evidenced in LIDAR views of the area (see below).  Feeder streams normally join the main flow as does a motorway on-ramp, but LIDAR illustrates the opposite and also shows the main river wider upstream.

LIDAR view of the apparently reversed flow of the Teme--it indicates South but actually flows North

LIDAR view of the apparently reversed flow of the Teme–it indicates South but actually flows North

So, the Teme where we joined it cuts through beds of Raglan Mudstone, Whitcliffe Formation (highly fossiliferous) and Downton Castle Sandstone, although this last I am not aware that we saw any in situ but some as building stones, on one of the bridges for example. An article HERE covers the theories appertaining to the formation of the gorge much more thoroughly (thanks to the author, Kathryn Francis)

Mike Brook’s Martley Rock App

It’s here and it’s FREE! A new app from Brooks Design, to complement the 17 that cover the length of the GeoParkway.  The new one builds on its predecessors, containing an absolute wealth of information and when you try it first time please do NOT think that you had seen it all, because I can assure you, you will not have done.  MartleyRocksFlyerThe full colour, GPS located, interactive Android and Apple based app presents maps, information panels, sections, photos and much much more to allow an understanding of and glimpse into how this amazing area situated in the parish of Martley came to be.

Search for MartleyRocks in your app store.

Thank you Mike of Brooks Design, you continue to develop this unique teaching resource; a picture it is said is worth a thousand words, these apps make libraries redundant.  Herefordshire and Worcestershire Earth Heritage Trust and ourselves are so very fortunate to have access to you and to these tools.

The app is a component of a much larger project “Voyages in Deep Time” :A bid is shortly to be submitted to the Heritage Lottery Fund, developed by the Herefordshire & Worcestershire Earth Heritage Trust.  The crux of the project is the development of apps (for smartphones/tablets) to engage principally, but not exclusively, a younger audience in the deep time heritage of our planet, with a focus on places in the counties of Herefordshire & Worcestershire. One of those sites of course being Martley!  A number of high profile organisations have kindly provided their backing and future support for the project. The aims of the project are summarised as:

Connect people, primarily young people, with the earth heritage of their surroundings and build appreciation that in the very distant past this place, their home, has been forged through many epic changes in environment, life forms and location.  As a means to achieve this, the proposal is to employ mobile device apps for use in the field, in combination with downloadable learning/creative materials, to facilitate individual/group interpretation of past environments which can then be made available to all via a web hosted interactive gallery. To further stimulate interest from the younger participants an app based game will be created which challenges the players to locate evidence of the deep past, whilst pitted against the clock, each other and challenges emerging from the deep time period they are currently ‘walking over’.

 

South Wales Geological Visit

What a day!  What a day fortune bestowed (that is the word) on us for the S Wales Geological Society’s visit to Martley, one of five set up when Ian and I attended the GA annual meeting in November last.  As I write it does not look so good for the visit of Reading GS today, 19th April.

Worcestershire’s countryside shone in all its glory, ploughed and harrowed fields lay cropless at this time showing off the true colours of underlying strata, undergrowth just awakening, exposures easily viewable.

SWGS bought along 13 members, none of whom needed my simple introduction to the geology of the region, so using an experienced teacher’s trick I talked about other things.  We made our way to Martley Rock, then across Kingswood Lane, along the valley edge:  the change in the colour of the dry, tilled earth in the fields to our right, from Triassic red to Silurian grey, was distinct under the clear blue sky.

On top of Rodge Hill

On top of Rodge Hill

Over the B4204 past the Tee and  up on to the ridge formed of upended, even over turned Aymestry limestone, above Pudford, glorious, Hay Bluff peeping over Bromyard Plateau, Brown and Titterstone Clee to the north west, valley of the Teme gorgeously spread below.  Lunch at the PONS seat, only one lunch mind, not like the Ramblers 9 mile foray a couple of weeks ago where Mike and I counted three.

Off the ridge to Lower House Quarry, Crinoid City to us,

Lower House

Lower House

 

 

but under intense gaze isn’t that a fault face, aren’t those slickensides and not only crinoids but cephalopods too.

 

 

Orthocone (Cephalopod) at Lower House

Orthocone (Cephalopod) at Lower House

 

 

 

 

 

 

 

From Lower House towards Woodbury

From Lower House towards Woodbury

 

 

 

 

 

 

Old Faces near The Canyon

Old Faces near The Canyon

 

 

 

Down into the dip, old quarries on all sides and into dense woodland, past

crags we worked on last week, see previous post, to the Canyon.

 

The Canyon

The Canyon

 

Thick layer of bentonite squeezed by cascade folds, maybe this ancient access way into the quarry was forged

along an old fault line.

 

 

 

 

Continuing along the forest path, up the Stairway to Heaven, around Penny Hill and into the quarry proper, discovering fossils at the famous face (Observer’s Book of Geology from the 50s, picture of this, captioned Martley, Wilts(!)).

Upside Down Corals (50p IS the right way up)

Upside Down Corals (50p IS the right way up)

My non geological colleague Colin found a striking example of the upside-downness of the formations hereabouts–a large piece of coral definitely growing towards the light but here at an angle of +-45 degrees down (see photo).

 

 

My constant mantra to the group, fascinated and intent as they were by each new exposure was that we were saving the best till last. This encouraged a steady pace

Analysing Calcite Veins at Scar Cottage

Analysing Calcite Veins at Scar Cottage

towards Martley and the pub with the last geological site being Scar Cottage and its incomparable quarry garden.  There certainly were a few wows and blimeys when the group rounded the corner and took in the view.  Here again the experts in the group came up trumps, seeing clear fault zones with fault debris between, proving with an acid bottle, the white veins were calcite.

At Scar Cottage

At Scar Cottage

 

 

Back at the pub, drinks and yes, SWGS were made to walk through the TVGS shop (just as National Trust) and indeed purchased two of our geology audits–thanks!!  We hope to see you at our symposium in October geo-symposium.eu.

Busk Coppice and Quarry Hill

St Mary's, Stanford with Orleton, looking South

St Mary’s, Stanford with Orleton, looking South

Under the Spreading Chestnut tree

Under the Spreading Chestnut tree

On Thursday February 14th, having opened all our cards and under grey skies, Ian, Mike and self, continued our foray into the Teme Valley and you know, sounds daft, but it really does feel like exploration when for us, checking out the rocks is a novel experience.  Anyway, we headed first to St Marys, Stanford, to see if we could find on the ground evidence of the mapped Raglan Sandstones in the land above the church. At the spot under a spreading chestnut tree we did indeed find sandstone rocks but these were scattered about and could possibly have been from local building works although at the time we preferred not to see them that way. To us they seemed similar to the church and to local walls of the old rectory just across the road.

Sandstone from West of St Mary's

Sandstone from West of St Mary’s

Sandstone from West of St Mary's

Sandstone from West of St Mary’s

 

 

 

 

 

 

Travelling up the road by car, we entered Busk Coppice to show Mike the large quarry found on our last visit—did this supply the stone to St Marys’ Stanford, but where is the lime kiln that Mr Churchill the farmer had told us about?

Lime Kiln in Busk Coppice

Lime Kiln in Busk Coppice

Lime Kiln Busk Coppice

Lime Kiln Busk Coppice

We wandered about down into gullies keeping in mind that it would not be far from the Bishops Frome layer, here underlying the quarried rock, St Maughans sandstone.  We gave up and called the farmer who directed us back up the track to a shooting platform and

Conical Kiln in the Undergrowth

Conical Kiln in the Undergrowth

 

Sketch of Lime Kiln, Busk Coppice

Sketch of Lime Kiln, Busk Coppice

goodness, there, not 3 metres from the trail, was a deep conical brick lined pit, a danger to anyone not seeing it, set in a levelled off terrace.  On the terrace below was a substantial brick built arched construction leading into the terrace and under the cone. A magnificent example of an ancient kiln, a little the worse for wear and needing attention to remove trees and soil but other than that looked like it could be relit straight away. This would have been used to make lime for mortar for building and for the fields and was slap bang into the Bishops Frome limestone, the calcrete (fossilised soil) referred to in other posts. According to Mr Churchill, a farm worker by the name of Tommy Tucker used to live in the arched kiln.  A little archaeological investigation sounds in order. Read Nils Wilkes fascinating study of Lime Kilns in Worcestershire HERE

So you burn limestone at 900C thus converting it from Calcium Carbonate to Quicklime and Carbon Dioxide, then you slake it with water making Calcium Hydroxide, known as lime putty, used as the base for a slow setting, traditional mortar still used in renovation work today.

That accomplished we went by car along the charming, twisty, switchback lane to just beyond Orleton until we reached the foot of Quarry Hill—the clue being in the name.

Valley Geological Map from BGS

Valley Geological Map from BGS, click to enlarge

This is an outlier from the main escarpment.  The geological maps show the limestone outcropping around the whole of the Bromyard plateau, with an island of it on top of Quarry Hill.

According to the maps the limestone was set in a sea of (Silurian) Raglan Mudstone only, and as we struggled up the wooded precipitous hillside littered with fallen trees, the redness of the soil seemed to indicate that this was the case.  There were occasional obvious trackways contouring the slopes, signs of forestry work or perhaps quarrying, who knows?  In the red roots of fallen trees we searched for stone as tell-tale of underlying rock and these at first were typical of Raglan sandstone.  Continuing to force our way upwards to the very top we discovered a substantial area clearly shaped by human endeavour.  There were no rock faces but the humps and bumps seemed to show that much of the top layer of limestone had been removed.  We did uncover large stones set in a semi-circle, perhaps the foundation of a kiln?

Conglomerate, both ruddy and grey with bedrock behind

Conglomerate, both ruddy and grey with bedrock behind

Just down the slope, we chanced upon exposed bedrock and took samples.  To our surprise these mirrored an earlier finding some way down the slope (that we had tried to ignore), of a coarse conglomerate, not what we expected at all.  One was ruddy, the other light grey, found 3-400mm above one another in clear layers.  The map shows (Devonian) St Maughans conglomerate in a number of places, but nowhere near this spot, and certainly none below the limestone. So how to explain this?  We retrieved our samples, cleaned them and will set them before the oracle as soon as we can.

Conglomerate

Conglomerate

Top of Quarry Hill, Mike on Access Trackway

Top of Quarry Hill, Mike on Access Trackway

Teme Valley around Stanford

Teme Valley around Stanford

More Quarry Hunting

hmm, our quarry was a quarry, a quarry or quarries that supplied stone (St Maughans) to local buildings, for example St Mary’s, Stanford with Orleton.

Another magnificent perfect blue sky winter day, ice in the shade, crystal views in all directions, what better place to be than the Teme Valley near Stanford even if for much of the time we were slipping through mud and tripping over brambles.  Having phoned first, Ian and I called and made our acquaintance with Mr Churchill who tenants Fall Farm.  He kindly allowed us on land alongside the Bromyard Road where Mr Lane had told us there would be a stone quarry, and indeed a crag is marked on the OS map.  Mr C told us of a lime kiln near the quarry and a place where years ago a farm worker used to live, saying he was surprised that the kiln was not listed.

After a bit of a false start on a trail that dead ended in impenetrable woodland we found good, if muddy tracks and around the corner there was the quarry.

Ian, for scale, on the quarry face

Ian, for scale, on the quarry face

Now well taken back into nature so very little rock was showing it was nevertheless clear enough to access the face.  On the day, Ian was the more agile so scrambled up the slope, found some rock and we brought back a few samples. After scrubbing up and a full dishwasher cycle see below for a picture of micaceous sandstone we believe to be St Maughans, a Devonian Formation, used in many local buildings. Realising that St M

St Maughans from the Quarry

St Maughans from the Quarry

along this part of the valley, sits atop Bishops Fromelimestone (formerly Psammosteus), Ian descended into the steep Vee side dingle below the quarry and lo and behold with a bit of digging about, found the typical noduley limestone that typifies this calcrete or fossilised soil, picture below.

We did not locate the lime kiln, this requires another visit, but one can only assume that it was placed there to take advantage of the calcrete,

St Mary's Church

St Mary’s Church

there being to our knowledge no other sources of lime this side of the valley.  We need to check but it could be that the main quarry was the source of stone for St Mary’s Church that sits so proudly on a promontory over the valley above Stanford Court, built there when a large lake was required in front of the Court.

Washed and dried specimens (click to enlarge):

Bishops Frome and St Maughans

Bishops Frome and St Maughans

Bishops Frome and St Maughans

BF and St M 2

Stanford Reminiscences

indebted to Robin Dean, good friend and churchwarden at St Mary’s Stanford with Orleton for the reminiscences as audio recordings for your enjoyment:

Robin’s note to me:

There is some good audio stuff on the parish website – the Temple was a house of ill repute according to John Shew (who used to farm Noverton) although it does not get into his recording (Stanford Temple and Church) – just in the description. Also a brief audio on Southstone Rock by John (Hermits living in the woods).

http://www.temevalleysouth.org.uk/media/

The Picturesque Movement and Satanic Teme Valley

Thanks To Kate Andrew, Project Manager leading the Building Stones Project based at the University of Worcester, for the following notes on the history and industry of the Teme Valley in the Shelsley area. These follow on from recent blogs about tufa and lost quarries.

Tufa: In terms of tufa formation, Beryl Harding wrote a really good paper about it in the Woolhope Transactions in about 2000 – this covers Southstone rock – photosynthesing moss and a drop in pH are critical to the CaCo3 coming out of solution and precipitating.

Coal: In Abberley there is a thin coal seam more or less at the boundary of the Halesowen Sandstone and Halesowen mudstone and then better seams that were mined up until the 1920s

The Temple and Stanford Court (the Court was the location of Forest Fencing) was a planned landscape garden and Kate suspects the Temple was part of that – could have had a cold plunge pool in it or been a place for banqueting and parties.

Kate’s Internet research reveals that Sir Edward Winnington (owner of Stanford court and brother in law to a Foley of Witley Court, before the Dudleys) and Richard Payne Knight were friends and both interested in the Picturesque movement, Stanford Bridge being built in 1794 by Nash, the architect of the Picturesque.

Richard Payne Knight was one of the founders of the Picturesque movement and created an enhanced landscape with hermitages, caves, springs, cold plunge baths etc upstream from all his forges and furnaces in Downton Gorge (on the Upper Teme below Leintwardine). The thrill was the contrast of dark satanic mills of iron production with wild “natural” beauty. This was in the 1780s-1820s time period.

A temple and hermitage are mentioned on the register of parks and gardens for Stanford Court, so Kate suggests that this is likely to be a Picturesque movement landscape hidden under the undergrowth. Kate conducted in depth research on Thomas Andrew Knight, Richard Payne’s younger brother and this involved looking into Knight family history and iron workings, among many other things.

Iron forging – the critical thing was decent water supply for bellows to get the furnaces up to high enough temperature and a good supply of wood close by for charcoal production – this is pre-industrial revolution/ Abraham Darby/ Coalbrookdale iron we are talking about. The iron ore could be brought in by pack horse or river as it is much easier to move than charcoal (which disintegrates if moved and is then no use) and decent water supply for power. You don’t need limestone flux if using charcoal for smelting as it is the sulphur in the coal of later processes that causes the problems. There were small forges all over the place in these parts, both smelting ore and working the pig iron with forge hammers – the critical thing was a decent water supply close to charcoal.

There is an interesting comparator with forges in the Downton Gorge owned by Richard Payne Knight.