Bristol U3A Geological trip to Lydney and Huntley.

We set off early to make sure we could enjoy our trip to Lydney and retreat from the foreshore before the tide rushed in, “faster than a galloping horse.”
We arranged to meet at Lydney Harbour at 1030. As it happened, I was the last one to arrive and I was a quarter of an hour early.
After ensuring that we were all suited and booted for the treacherous Severn Foreshore, we set off.
Anna was leading the trip and had previously carried out a recce but the reeds had grown so much since then that it was difficult to find the way without being able to see the ground ( mud ).
We fought our way through the reeds, over a couple of mud banks and then found ourselves on the rocky foreshore which was mainly made up of very grippy red  mudstones of the Raglan Marl Group.
We surmounted these and then had to pick our way over some mud banks. From the erosion surface of the mud banks, deposition layers could be seen so our assumption was that the Severn foreshore was prograding in this area.
Then we came to a beach area underlying a cliff. This is what we had come to see. This is the famous Lydney Cliff SSSI – see citation below.
We walked further on to the point to investigate the strata and cliffs. We also worked out where the Severn Railway Bridge was before it was destroyed in 1960.

You will be glad to hear that we got back to the Harbour before the tide came in.

Height of image approx 3m.

65a2bd80-c76e-4af6-aaa4-eb81d5dbf9c9

Lydney Cliff showing nodular calcrete.

Calcrete notes

Soil formation – pedogenesis – in the Silurian and Devonian periods

Soils started to form in the Silurian from the products of chemical weathering from high ground resulting in minerals and clays being deposited in basins. Early organic soils containing plant material have been found in the Early Devonian Rhynie Chert, near Aberdeen, where fossils of early vascular plants have also been found. Before this, in the late Silurian, there were only inorganic, shallow, microbial protosoils. The development of deeper and stronger plant rooting systems on ArchaeopterisLepidendropsis/Protostigmaria),  and Rhacophyton in the Late Devonian resulted in deeper soils containing more organic material by the process of pedoturbation.

Calcrete genesis in the Devonian period.

Clays from the smectite group are found in Devonian palaeosols. These clays take up water and swell in wet conditions and so shrink when they dry out because of evaporation. This results in vertical fissures which allow fluids to penetrate the soil. With each hydration / evaporation cycle, the concentration of calcium and magnesium  carbonate minerals increases and these saturated mineral solutions react with the soil altering the aluminium based clays to either calcretes or dolocretes. This alteration is post deposition as can be seen by the limited penetration down from the surface. Older calcretes tend to have been altered to dolocrete.
Calcrete, also known as Caliche in Latin America,  cannot form in the present climate of the British Isles as it needs a mean wet season rainfall of 100-500mm and a mean annual temperature of 16 – 20oC. It is forming in modern times where this climate occurs in places such as Arizona USA, Gilgai Australia, Kankar India and areas of Mexico.
Calcrete is the formation of a Duricrust from calcium carbonate, as other minerals are involved, they are called ferrocrete etc.
In the Atacama Desert in northern Chile, vast deposits of a mixture, also referred to as caliche, are composed of gypsumsodium chlorideand other salts, and sand, associated to salitre (“Chile saltpeter”). Salitre, in turn, is a composite of sodium nitrate (NaNO3) and potassium nitrate (KNO3). Salitre was an important source of export revenue for Chile until World War I.
These deposits were mined because of their high nitrate content. They supplied the material for nearly all the explosives used in WW1. At it’s height, Chile was exporting 25 million tonnes a year.
These deposits are the largest known natural source of nitrates in the world, containing up to 25% sodium nitrate and 3% potassium nitrate, as well as iodate minerals,     sodium chloride, sodium sulfate, and sodium borate (borax). The caliche beds are from 0.2 to 5.0 m thick, and they are mined and refined to produce a variety of products, including sodium nitrate (for agriculture or industry uses), potassium nitrate, sodium sulfate, iodine, and iodine derivatives.
This mining was superseded by industrial production of explosives and fertilisers in Europe using ammonia produced by the artificial fixation of nitrogen using the Haber–Bosch process.
In the UK, Calcrete occurs in the Upper Silurian and Lower Devonian rocks and so are used as a marker for the start of the Devonian period.
Depending on the location, it is called Variously: Bishop’s Frome Limestone, Chapel Point Calcrete etc.

The lower part of the cliff consists of mudstones of the Raglan Marl Group but above this, for most of the cliff height it consists of the Bishops Frome Limestone, which is a nodular calcrete.  Towards the top of the cliff are cyclothems of nodular calcrete and siltstone / mudstones of the St Maughan’s Group.
Below the current beach level, fish fossils have been found. The cliff is eroding quite fast as shown by the number of nodules on the beach.

3731a2ab-8d51-42f6-ac0c-a5b9a0510c24

More details can be found in the GCR at

BGS.  England and Wales sheet 233. Solid and Drift.

Lydney 1

Extract from sheet 233 showing Lydney Harbour, a cross section of the anticline and the Silurian / Devonian transition.
We had a long discussion under the cliff about calcrete and it’s polymorphs. Then we wandered further along the shoreline investigating the various strata and noting the calcrete in the cliff above us. It was then time to turn back and retrace our steps to Lydney Harbour. We then decided it was time for lunch so out came our sandwiches.

Then it was time to set off for Huntley Quarry. This took us about half and hour, we regrouped by Huntley Church. Unfortunately the garden centre which used to provided parking, drinks and food is no longer. We set off up the hilly path by the side of the school into a beautiful wood. We followed the path along to the Geological Reserve which is owned by Gloucestershire Geology Trust. We read the interpretation bards along the way so we knew a little of the structural geology by the time we got to the quarry. This was just as well as nature had invaded the quarry and some of the rock faces couldn’t be seen. Never mind, we could see and access the main face so spent some time investigating the many features of sites 2 and 3. Site 1 was completely covered by vegetation.

daf3b13a-3293-4f4f-91e5-618d45422ce3

I won’t go into the detail of the structural geology here as that would just be repeating the text from the excellent guide that is available from Gloucestershire Geology Trust – £2.00 + £2.00 P +P.

Suffice to say, it will keep geologists and other interested people investigating for hours as the rocks vary from the Late Ordovician 485 – 443 mya to the Triassic 251 – 201 mya.  These include volcanic ash. Then there were the tectonic movements of the Blaisdon Fault and the accommodation movements, including thrust faults, that were partly caused by the Variscan Orogeny 390 – 310 mya.

Hunt

After much discussion, we walked along to Ackers Quarry to see the beds of Triassic Bromsgrove sandstone. We then returned to the cars and the trip home after a very interesting day

References

Guides

Huntley Quarry  – Geological Reserve Guide – Gloucestershire Geology Trust

Huntley Quarry – Teacher’s guide – Key stage 3 notes – Gloucestershire Geology Trust

Lydney Town and Harbour – Trail Guide – Gloucestershire Geology Trust

Maps

Outdoor Leisure 14 – Wye Valley & Forest of Dean – Ordnance Survey

Monmouth, England and Wales sheet 233 – Solid and Drift – BGS

Geological Conservation Review GCR

Lydney OS SO 652017 – http://www.jncc.gov.uk/page-2731 – Fossil fishes of Great Britain. Chapter 3: Late Silurian fishes sites of the Welsh Borders. – GCR

Information on Calcretes
Various sources inc: Dr Dave Green field trip of 9th March 2008
Dr Nick Chidlaw, “Soil Evolution, Arid and semi arid climates, diagrams”

© Richard Kefford         2020         Eorðdraca.         

My books are for sale here:         Richard

Geology Book launch

I had a wonderful experience recently.

I had an e mail from BRERC ( Bristol Regional Environmental Records Centre ) which is the central repository for the environmental data for the region. The Bristol Region covers the West of England area, with Bristol and Bath at its heart. To the North it incorporates Thornbury and Wickwar; to the south, chew Valley Lake and the edge of the Mendip Hills; to the west, Weston – super – Mare and the estuary of the Severn; and to the east are the Cotswold Hills.

The e mail said that BRERC’s latest book “Geological Sites of the Bristol Region” had been published and copies were available to be collected at Bristol Museum.

I rushed over there and duly received my FREE “Author’s copy”, cover price £19.50. To say that I was chuffed is perhaps an understatement.

My contribution to the book was an article on the Redcliffe Caves and a geological poem – Search this blog for “Earth Song.”

I encourage you all to rush out and buy a copy because it is an excellent and well written book by a class act of Earth Scientists, and me, but I understand if you wish to think before buying because of the price. It is a reference book.

This book 5 in BRERC’s series of environmental books.

More information about BRERC can be gained from their web site:

http://www.brerc.org.uk

Here is a sample page from the book.

Geo book 2

© Richard Kefford         2020         Eorðdraca.         

My books are for sale here:         Richard

Time

Time

We have plenty of time. We can shrink it or stretch it out just by our actions. Think back to when you are doing something that really interest you, everything else shrinks to the background. When you have completed what you wanted to do so desperately, you look and realise that  a lot of time has passed without you realising. In the flow they call it. But wait, do we really have plenty of time. There is plenty of time, about 13.8 billion years has passed since the universe was born but we do not have access to all of it. Once we were born we are allowed perhaps 100 years. That is not a large fraction of the time that this universe has been around. In fact 100 divided by 13.8 billion is about 7.246376812 x 10-8so we are but a pinprick in the overwhelming space time of the universe. Einstein then worked out that time can be varied by the speed at which you move – time dilation effect. Don’t ask me to explain it, just look it up.

Take the white cliffs of Dover as an example. They are made of the coccolith calcite plates that are formed by coccolithophores, which are aquatic, single-celled algae. They are marine and live as phytoplankton in the photic zone of the open ocean, where they are a major source of food and a significant producer of oxygen. They are very small, about 2-5 micron in diameter. These plates form the majority of the chalk.

Now some simple maths. 

The chalk cliffs of Dover are some 80M high. The chalk was laid down during the Cretaceous period which lasted 80 million years. A simple calculation shows that, on average it took one thousand years to deposit 1 mm of chalk.

So, if you lived in the Cretaceous, you wouldn’t even notice that chalk was being deposited. In fact the household dust that builds up and needs removing every week or so – depends how house proud you are  – is deposited at a much faster rate than the chalk cliffs of South England. I’ll leave you to do the maths on this one. It goes to show one of the principles of geology – most processes happen very slowly and so require a great deal of time – luckily, there is plenty.

So we now have some idea of the time we are dealing with, even if we cannot directly relate to them. One of the problems with geology and dealing with these scales is that it makes you realise how insignificant humans are.

Here are some facts that might bring this home to you.

Modern humans  – Homo Sapiens – have existed on Earth for a short time – about 200,000 years. Dinosaurs existed on Earth for a little longer time – about 135 million years

Maths again!

This means that dinosaurs lived on the Earth some 675 times as long as modern humans have. Do you think humans will be around 135 million years in the future? No, me neither!

So, in spite of “dinosaur” being used as an insult for an out of date person, they did quite well and have been some of the most successful species on Earth.

A small diversion. I once went to a working quarry a few years ago in Gloucestershire, for a look around. Quarries are fascinating to geologists as they open a 3D window in the rock under our feet. I went to the mine manager’s office, as he was going to show me around. It was a warm day so the office door was propped open by a flat piece of rock. I looked at the rock – as you do – and saw that there were markings on the surface. As a conversation starter I asked him about them. ‘Oh those are dinosaur footprints, we come across a lot of those. They are a nuisance because they are really damage to the surface of the flat laminations so it is just a piece of waste rock to us’. I had a closer look and saw that it was as he said – it had the three toed foot. I realised after I had left the quarry that I should have asked him if I could have one of his scrap rocks with the foot print.

Another problem when you are dealing with geology is that you can become a little blasé about these scales. In the area where I live there are several limestone ridges that were deposited in the Carboniferous ( 359 – 297  million years ). It is simple to find fossils in these rocks so when you break a lump open and see a fossil coral there you realise that this fossil has been waiting there for over 300 million years – just waiting for you. Then you might come across some Triassic ( 250 – 201 million years ) and you start thinking that these rocks are fairly young. But when you see an archeologist on TV going on about “very old Roman finds that are two thousand years old”, you start to realise what deep time is. 

Then you might go to North West Scotland and place your hand on some Lewisean Gneiss and realise that it is over 3 Billion years old – two thirds of the age of the Earth. What a privilege to be able to see and touch these ancient rocks!

Language.

Geology is an international science so there are some lovely words to play with. Here are a few of my favourites.

Paleoproterozoic
Rhaetic
Solifluction
Slickenside
Batholith
Olivine
Wolfram.
Galena
Tourmaline
Subduction
Obduction
Lithification
Coccolithophores
Phytoplankton

As a writer, I often use some of these words in stories, sometimes as the names of characters. Slickensides sounds like a hairstyle. I remember writing about Solly Fluction who was an author who wrote detective novels.  I think my favourite is still Paleoproterozoic – it just rolls off the tongue.

© Richard Kefford    2020                               Eorðdraca

My books are for sale here:      Richard

Earth Song

Precambrian 

I was in hell being bombed in the Hadean. 
I was just alive in the Archean. 
I was long present in the Proterozoic. 

 Paleozoic 

I was changed by life in the Cambrian. 
I brought order to the Ordovician and 
I just survived the Silurian. 
I nearly drowned in the Devonian, all those fish! 
I made coal in the Carboniferous, delta, changes. 
I was probably present in the Permian desert dust storms. 

 Mesozoic 

I was a playa in the triple, arid Triassic, 
I evolved with many ‘ites during the Jurassic. 
I chalked the Cretaceous, fashioning forans and flints. 

Cenozoic 

I nearly perished in the Paleogene, 
I numbered all the Neogene. 
I quaked in the sometimes chilly Quaternary. 

Holocene 

I have lived so long, it may seem perverse but 
I want to live to the end of the universe. 

I am the worse for wear and war weary. 
I am your home, your Earth, cherish me dearly. 

© Richard Kefford 2020 Eorðdraca

My books are for sale here:  Richard

No Planet B – 17

This will be a very short post.

It is addressed to all who will read it with interest, discard it as Rubbish, ignore it but maybe, just maybe, there will be one person who reads it and then has the glimmer of an idea and goes on to develop it to save our human planet.

Are you that person? Then here is your challenge.

If you could invent something that would cure the climate and nature crisis, what would it be?

No limits, just use your human capacity for thinking.

IF NOT YOU, WHO?

Looking forward to hearing from you. There is no copyright on this article. It first appeared in “Wired.” It is a question that was asked by his 11 year old on a long car trip with his journalist father.

Richard Kefford 2020 Eorðdraca

My books are for sale here:  Richard

Why I love Geology II

There are two huge scales in geology, one is Distance and the other is Time

When I was following a geology course with the Open University, one of the course modules was called “Quarks to Quasars” which discussed the scale of distance.

Distance

The purpose of this was to demonstrate the size and distances that science covers.

Quarks are the fundaments constituents of matter and are smaller then 10-19 m in size, while quasars represent the most distant astronomical objects it is possible to observe and are up to 1026 m away. So the obvious question is, ‘How much bigger is the distance to a quasar than the size of a quark?

This needs a little maths – only a little:

Divide the distance away of a quasar by the size of a quark

1026 +19  =  10 45

So the distance to a quasar is 45 orders of magnitude greater than the size of a quark.

These two length scales – separated by a factor of a billion, billion, billion, billion, billion. represent the extremes of human comprehension of the Universe so quarks and quasars therefore serve as convenient limits between which we might attempt to understand the Universe as a whole. 

So if we start with…

A quark which is a billion times smaller than an atom

An atom is a billion times smaller than an apple

An apple is a billion times smaller than Jupiter

Jupiter is a billion times smaller than the distance to the nearest stars

The nearest stars are a billion times nearer than quasars.

These extremes of length of scale are what geologists play with. Talk about,”The world is your lobster” !

Time

The other scale is time. The first question is: “How old is the Earth?”

There are two wildly divergent answers.

One is ‘calculated’ from material in the Bible that says the Earth is about 6,000 years old and the other, from science is that the Earth is about 4.54 billion years old.

I suppose you could choose either but, as a geologist, I can see just by looking at rocks and thinking about the processes that made them that the Earth cannot possible be as young as 6,000 years. Believing that is equivalent to believing that man and dinosaurs used to live on the Earth together until ‘recently’.

The age of the Earth is 4.54 x 109. or 4.54 billion years  +/- 500 million

There are many strange names for the different divisions in geological or “deep” time. It is hard to remember these so I wrote a mnemonic poem a while ago”

Earth Song

Precambrian

I was in hell boing bombed in the Hadean.
I was just alive in the Archean.
I was long present in the Proterozoic

Paleozoic

I was changed b y life in the Cambrian
I brought order to the Ordovician and
I just survived the Silurian.
I nearly drowned in the Devonian, all those fish!
I made coal in the Carboniferous, delta, changes.
I was probably in the Permian desert dust storms

Mesozoic

I was a playa in the triple, arid Triassic,
I evolved with many ‘ites in the Jurassic,
I chalked the Cretaceous, fashioning forams and flints.

Cenozoic

I nearly perished in the Paleogene
I number all in the Neogene
I quaked in the sometimes chilly Quaternary.

I have lived so long, it may seem perverse, but
I want to live to the end of the universe.

I am the worse for wear and war weary,
I am your home, your Earth, cherish me dearly.

The history of the Earth is written in the  rocks for all who wish to read it.

We find no vestige of a beginning,—no prospect of an end.” James Hutton 1726 – 1797

So geologists are free to play in a huge Universe and within an enormous timescale.

One problem apart from an overwhelming feeling of awe for the natural world is that the more you find out, the more you realise that your existence within all these wonders is incidental and you are insignificant and irrelevant to everything that is going on.

Take the white cliffs of Dover as an example. They are made of the coccolith calcite plates that are formed by coccolithophores, which are aquatic, single-celled algae. They are marine and live as phytoplankton in the photic zone of the open ocean, where they are a major source of food and a significant producer of oxygen. They are very small, about 2-5 micron in diameter. These plates form the majority of the chalk.

Now some more simple maths. 

The chalk cliffs of Dover are some 80M high

The chalk was laid down during the Cretaceous period which lasted 80 million years.

So a simple calculation shows that, on average it took one thousand years to deposit 1 mm of chalk.

So, if you lived in the Cretaceous, you wouldn’t even notice that chalk was being deposited. It goes to show one of the principles of geology – most processes happen very slowly and so require a great deal of time – luckily, there is plenty.

So we now have some idea of the distance and time we are dealing with, even if we cannot directly relate to them.

One of the problems with geology and dealing with these scales is that it makes you realise how insignificant humans are.

Here are some facts that might bring this home to you.

Humans have existed on Earth for a short time- about 200,000 years

Dinosaurs existed on Earth for a little longer time – about 135 million years

Maths again!

This means that dinosaurs lived on the Earth some 270 times as long as modern humans have.

Do you think humans will be around 135 million years in the future? No, me neither!

So, in spite of “dinosaur” being used as an insult for an out of date person, they did quite well and have been one of the most successful species on Earth.

Another problem when you are dealing with geology is that you can become a little blasé about these scales. In there area where I live there are several limestone ridges that were deposited in the Carboniferous ( 359 – 297  million years ). It is simple to find fossils in these rocks so when you break a lump open and see a fossil coral there you realise that this fossil has been waiting there for over 300 mya – just waiting for you. Then you might come across some Triassic ( 250 – 201 million years ) and you start thinking that these rocks are fairly young. But when you see and archeologist on TV going on about “very old Roman finds that are two thousand years old”, you start to realise what deep time is. 

Then you might go to North West Scotland and place your hand on some Lewisean Gneiss and realise that it is over 3 Billion years old – two thirds of the age of the Earth. What a privilege to be able to see and touch these ancient rocks!

Language.

Geology is an international science so there are some lovely words to play with. Here are a few of my favourites.

Paleoproterozoic
Rhaetic
Solifluction
Slickenside
Batholith
Olivine
Wolfram.
Galena
Tourmaline
Subduction
Lithification

As a writer, I often use some of these words in stories, sometimes as the names of characters.

Is it any wonder that I love geology?

©  Eorðdraca 2018 My books are  here Richard

Why I love Geology III

Tyntesfield

‘Please pass the kippers, dear,’ requested Mister Gibbs,’ I feel I shall need the energy today so I intend to have a good breakfast.’ 

‘Good idea my husband, we don’t want you expiring during the day from a lack of sustenance do we? Why especially today though?’ enquired Mistress Gibbs.

We are in dire need of extra supplies of limestone both for road stone to repair the drives around the estate and also to feed the voracious lime kilns that are busy producing fertiliser for the Home Farm and mortar to complete the sawmill we are building in our old limestone quarry. ‘ he mansplained.

‘Why cannot you just put more men to work on that quarry?

‘We are quite deep in the hillside now and any further production of limestone will require much work just to dig down to reach the stink stone and we have no need of the Keuper Marl above it.’ he patiently explained to his wife.

‘I have had a couple of good men these last few weeks searching for a good site for a new quarry; one that will need less preparation to make it fit for full production. We will start quarrying with a full gang this morning and I intend to be there for most of the morning to ensure that my wishes are carried out exactly. We also have another load of coal coming in from Mr Lucas’ mine in Nailsea to fuel the lime kiln, so you can see why I have need of much sustenance this morning – I need feeding just as much as the lime kiln. Tee Hee,’ he laughed at his little joke. ‘Perhaps one more plate of devilled kidneys and a spoon or two of kedgeree from this famous sideboard.  That should sustain me until dinner.’

‘Yes, dear,’ acquiesced his wife, not really sure what he was on about, ‘you know best, dear.’

‘Indeed,’ agreed Mr Gibbs – the first Lord Wraxall.

*****

‘Where do you want to start your Lordship?’ asked Samual Kellaway, the recently promoted quarry Supervisor.

‘I think it is best to start on this corner. I can see that you have stripped the trees and the understory from the area of the planned quarry, that’s good work,’ said George Abraham Gibbs. ‘We can strip off the top soil and cart it to the Home Farm to improve some of the shallow soil areas. Then of course we can set about quarrying off the Keuper Marl overburden. This we will then cart to the saw mill as I am thinking of building an extension to the sawmill and can use the Keuper for rough building work. I expect to be able to start work on the underlying limestone tomorrow – that is, if your survey is correct of course.’

‘Yessir, your lordship,’ said Sam, sweating. He knew his promotion was on the line.

‘If you need me, I shall be up at the lime kiln for the rest of the morning and back to the house this afternoon.’. I’ll be here again tomorrow morning to see how you are getting on.’ He shouted over his shoulder as he cantered off up the track at the side of the wood.

*****

‘What are you doing today George, are you playing with your new quarry?’

‘Yes, I shall be working on the new quarry – not playing, Ursula, we need the limestone it contains for the estate.’

‘Of course dear, you had better be going then. Have you had your fill of breakfast?’

‘Yes thank you my dear, my belly is full of devilled kidneys.’

‘George, don’t be so vulgar!’

*****

His groom had ridden up from the stables with his horse. George hoisted himself up into the saddle and then rode up past the chaplain’s house and Home Farm to the site for the new quarry on the edge of the Sidelands Wood.

Sam had all his quarry men working since six that morning so the Keuper Marl had been scraped off and carted away to the sawmill quarry. The freshly exposed limestone,”stinkstone’ as the quarrymen called it because of the sulphurous smell it gave off when crushed, was shining freshly in the sunlight.

‘Right then Mr Kellaway, let’s start with the first drill and see what we’ve got shall we?’

‘Yes, your lordship,’ agreed Sam as he signalled to two of his best men to start drilling. One man held the steel drill in a pair of tongs and twisted it 90 degrees between each hammer blow.and the other hit it regularly with a sledge. It was soon some six foot deep in the rock and the ‘hammer man’  was able to descend from his wooden staging. The drill was pulled from the hole and the dust was blown out manually with a thin tube. A cylinder of black powder was inserted in the hole, then an electrical detonator followed by more black powder which was carefully tamped by a wooden pole. The detonator cable was run back some distance from the hole and then connected to the hand generator. Sam turned off the safety switch and then asked if Lord Wraxall would do the honours of setting off the first blast. George stepped down from his horse as Sam blew his blasting whistle, gave three minutes for all to get clear and then Lord Wraxall bore down on the generator handle. There was a mighty explosion, which unsettled George’s horse and then the cliff of limestone surged towards them. All had a cup of tea from the urn accompanied by many a hand rolled cigarette, while they waited for the dust to settle. They then started shovelling the limestone into the waiting carts which were pulled up to the lime kiln by  the working horses.

Lord Wraxall inspected the limestone face with Sam and they both agreed that the limestone was of good quality and would be equally good for road stone and feed for the limekiln. This was the start of a long life for the Sidelands Quarry. 

*****

We three arranged to meet at 1030 at the NW corner of the car park. It was 1st October 2018, a lovely sunny Autumn day.

We headed for the Sidelands Quarry – now long disused as a quarry but with a new life as a location for a 4G telephone mast. Sidling through the gaps between the mast and the cabinets of ground control gear, we entered an enchanted area. The old quarry walls rose on each side, trees had made their homes in and around the quarry, making it a dark, damp place with the quarry floor colonised by ferns and brambles. Ivy dangled thickly from an overhanging tree.

Speaking as a geologist, the wonderful thing about quarries is that they expose the underlying rocks that you may otherwise never get to see. This quarry is a case in point. There are two rocks exposed along the working faces. One is what the quarrymen were looking for, which is Clifton Down Limestone. Above this is the Mercia Mudstone Marginal Facies. The wonderful thing here is that the junction, or unconformity, can be clearly seen between the two rocks. The CDL is about 340 million years old – mya – from the warm, tropical Carboniferous sea, while the MMMF is around 150 mya. from the Triassic. This formed from the eroded products from the adjacent highlands as sharp edged clasts can be seen within it. This means that you can span 190 million years with one hand. I find that awe inspiring. Also in this quarry can be seen a myriad of dog tooth spar – crystals of calcite – Calcium Carbonate. Some are in sheets on a fault surface and some are in huge vugs – or caves, lined with the same crystals.

After looking at all these wonders, we then wandered off, through the check in control and then we were free to poddle along, enjoying the landscape and weather as we discussed the Chaplain’s house and then we spotted the moon in the clear blue sky – why hadn’t it gone to bed?  We arrived at the saw mill quarry. There was some discussion about the building stones used to build the mill in the quarry and, of course, the old style mortar that had recently been used to repoint the walls of Triassic MMG. This had the charcoal bits in it that showed the Calcium Oxide had been produced in a lime kiln. It was then time to inspect one of the Oolitic Limestone window surrounds – to see the multitude of Ooids from which it was composed and the complex cross bedding.

After checking and identifying all the building stones in the mill, we wandered off down the path leading to the formal gardens, noticing en route the phenomenal lumps of calcite crystals that were heavily disguised by the moss growing over them. I wonder how many National Trust people know that these wonders are there? And, if so, why they don’t clean up one of the lumps of crystal and put it on display with a spot light on it, in the check  – in area?

We left the crystal path behind and ventured down the main front steps to the flower gardens where a team of gardeners were hard at work. After admiring a beautiful specimen of a monkey puzzle tree Araucaria araucana. Then it was through the ha ha retaining wall and along a paved path to the walled gardens.

After all this walking, talking and looking at the wonderful landscape, we felt the need for some refreshment. Luckily there was a cafe to hand so we settled down with a coffee each and tried to process all we had seen. The coffee was hot and strong so we managed to get a lot of talking done but no note taking or writing, which was our original intention. We realised that we would have to retain our findings and impressions of this wonderful place until we got back to our garrets to get them down on electronic paper.

Now it was time to retrace our steps but we decided to take the curved road, past the huge sequoias along the way. From here we could just see the stables, through the trees. We passed the main entrance to the house, walked past the chapel then found ourselves back at the top of the crystal path. We followed the road as it curved around the gully down to rose garden – admiring the collection of water-worn limestone rocks by the side of the road. The conclusion was that they were formed in the phreatic rather than vadose zone because of the almost complete roundness of the wear. but this is open to argument and proof.

For some reason I was quite hungry and felt a desire to eat some devilled kidneys and, perhaps some kedgeree. Unfortunately there was none on the menu at the cow shed restaurant. Very strange as I had not eaten devilled kidneys for about 43 years ago when I left the Royal Navy and even longer since I had eaten kedgeree.

We passed through the gauntlet of souvenir shops in the Home Farm buildings and then we were free to return to our respective transports to return home and reflect on a wonderful, inspiring morning. Shame about the lack of proper breakfast food…

With thanks to the National Trust.

©  Richard Kefford Eorðdraca 2018

My books are for sale here:   Richard

Why I love Geology – I

I was born in Brighton and grew up on the South Coast at Lancing, so I thought all rocks were white, soft and had flints buried in them. I saw this on trips to the beach when I saw the chalk cliffs of the Sussex coast towering above me. I saw this in rural chalk pits on the South Downs and the great quarries supplying chalk for the huge, linear cement kilns.

I was happy with this although I was a little bemused and unsatisfied that everyone answered my query, ‘how did the flints get there?’ with a careless, ‘Oh, they just growed there.’ This seemed to me to be both unscientific and unsatisfactory.

One day my Dad took me on a trip to the science museum in London. This was very exiting for me because, as we didn’t have a car, we went by train to London, Victoria from Brighton and then took the underground to South Kensington. I really enjoyed the day at the museum and I still remember several exhibits from there, the huge pendulum in the foyer, the ‘difference engine’ and the many working exhibits that had buttons to press and handles to turn.

What made the biggest impression on me was the train journey. We left Brighton and soon entered a tunnel that debouched us on to the Weald – that magic land between the South and North Downs. It was so different to the South coast littoral. Different trees, different vegetation. The whole countryside looked different. Then we went into another tunnel to burrow under the North Downs. I quickly noticed that the North and South Downs faced each other. I asked my Dad why of course – he must have answered many, many questions from me that day. He then spent a good half an hour explaining, with the aid of several sketches that there was once a vast chalk dome over the Weald, connecting the North and South Downs. All the chalk in the middle had been eroded away to expose the different rocks of the Weald. This was obviously wrong. How could such a huge dome exist and then get worn away, where was all that material now? I didn’t argue but determined that, one day, I would research all this and find out the true story for myself.

The one day my Dad asked if I would like to go to the science museum again. It was a chance for another day out so I said yes but I knew by now that there was a Natural History Museum nearby so, ‘could we go there instead?’

We did the journey, train and underground and started into the NH Museum. I’ll never forget that moment, walking up the few steps up under that fabulous multi coloured arch to see the famous round table made from so many different rocks.

We spent the day dashing from cabinet to display to mineral specimen – and back again until my Dad had had enough and I was exhausted but exhilarated. A day in Aladdin’s cave. A day to remember. Looking back over the years, I realise now that it changed my life.

On our annual holiday we went to a different place each year, Whitby, Oban, Largs, Weymouth and I slowly started to recognise different rocks. This was a revelation – not all rocks were as white and soft as chalk.

So the obvious thing to do now was to work hard at school, get three good ‘A’ levels and then choose a University such as Durham which is known for teaching Earth Sciences and is surrounded by interesting geology.

I took my GCEs, left school without knowing the results and joined the Royal Navy – against all advice and ‘insistence’ from the school and my parents. I had always wanted to join the Royal Navy since I was about ten and I wasn’t going to give up me dream for a few rocks was I?

I served on various ships as an Artificer – Engineering Technician –  and visited a lot of places around the world but left after 13 years because they wanted me to go into submarines – and I didn’t want to. What was the point of travelling the world if you didn’t know where you had been and got no chance to see anywhere except Faslane in Scotland? I did a few different civilian jobs until I found one that suited me. This was a job with Bowater / Rexam / SIG – the same company but taken over several times. I ended up as project manager for UK, Ireland, Benelux and Scandinavia. I stayed there for 30 years until I was made redundant. I was then asked to come back and do the same job on a self employed basis. This I did! As I was now 62 I started thinking about preparing for retirement. The children had left home, I now had less responsibilities so I thought about going to University to see if I could manage a degree and obviously chose Earth Sciences.

I contacted the admissions tutor at Bristol and asked if they would accept an old fogy like me as an undergraduate student. Dr Mary Benton said that my age wasn’t a problem but as I hadn’t studied intensively for many years, she suggested that I take an introductory course with the Open University to see if I could cope with the intellectual rigour required. 

I contacted the OU, looked at the different pathways to the degree I wanted and started a course called “Science starts here”. This was a short course and would contribute 10 points towards the 300 I needed. Well it was a start. I found I could cope very well with the science and maths and ended up with a mark of 94%. I took this as a sign that I could do it! I also found that I really enjoyed the OU style of distance learning so I planned to stay with the OU and not go back to Bristol Uni. I carried on with the Earth science route until there was a hiatus so I thought I would do a short course to fill the gap. This was a course called “start writing fiction”. I absolutely loved it. This what I was born for, “Tell lies and write them down”. So now I had a problem. I could carry on with the earth science and get a geology degree or switch to creative writing and get an arts degree. The OU is made for people like me as I could now switch to an “Open” degree get a minimum of 150 ‘science’ points and the get the other 150 from Arts courses and still end up with BSc. So this is what I did. Half geology and half creative writing.

This took me six years but I achieved my objective of a BSc. I now had some knowledge of the two subjects I wanted and had learned how to learn. I now knew what I didn’t know and I could teach myself that with a lot of research. 

I graduated at a ceremony at Poole at the age of 68, a lifetime’s ambition fulfilled and no, I wasn’t the oldest one there! I am a great fan of the OU – I think it is a wonderful institution. Harold Wilson said that it was his proudest achievement. The OU now teaches 75% of the Geology undergraduates in the country.

I now had the tools I needed to do exactly what I wanted in my retirement.

I write geology books about my local area. I lead geology trips for Bristol Naturalists and the Bristol U3A geology group and go for long walk in the countryside – looking at the landscape and working out how the underlying geology has shaped the landforms and decided on the most suitable vegetation for the type of soil produced by the rocks.

A couple of local examples;

1 – Tyntesfield estate.

A huge estate with a gothic mansion built by the Gibbs family. These are several disused quarries on the estate. In one there is a clear unconformity – Triassic rocks are lying on carboniferous rock so that with two hands you can bridge 90 million years of geological history and deduce what the climate and other conditions were at the time.

2 – West Tanpit Wood.

Here there is a range of rocks from the Devonian to the Carboniferous. There are fossils and a growing Tufa dam in the wood.

All this can be easily seen and understood without any expeditions to exotic places.

3 – Boreholes

At anytime over the last 150 years or so, if someone drills a borehole to find water or coal etc, the British Geology Society ( BGS ) keeps a record of the bore log and all the information therein about the strata the bore passes through. All this information is then publicly available on the BGS web site.

An example:

OS Grid position – ST57SW9 — WATERCRESS FARM BORING

Depth – 490 ft.

This borehole was drilled in 1903 to attempt to find a ready supply of water for the Tyntesfield Estate owned by the Gibbs family.

It was drilled to a depth of 490 feet and records the different strata – including coal seams – that was seen in the recovered cores.

There are records of borings from all over the country so the history of any particular area can be deduced. It purely depends on where the holes were bored and to what depth.

After I left school, the theory of continental drift, then onto plate tectonics was refined and now you can track the movement of eg the UK across the globe. It was South of the equator in Devonian ( 419 – 358 million years ago to todays location – at the moment as the continents are still wandering about the planet. So much to learn about and understand, all underpinned by science.

So you can see that geology is a combination of field work and research that can be carried out indoors.  I spend a lot of my time outdoors happily trudging up and down hills while observing and measuring. I also spend a lot of time at home putting all these results together and writing out a report on the results. I have a great time!

I write books, stories for my grandchildren and short stories for the U3A writing groups I attend. Three of us have formed a blogging and publishing group for our output – novels, poetry, short stories and geology books. 

I found out my Dad was right about the chalk dome in Sussex and I have a rough idea of how the flints got where they are.

I love geology!

©Richard Kefford          2018           Eorðdraca.

My books are for sale here:   Richard

Trial post 1

Welcome to my rocky blog. Anybody know where this pic was taken?

 

This is Coire Lagan on the Isle of Skye. My favourite place.
Here you can see a classic glaciated corrie formation with these features and a wonderful view – on a clear day.
Gabbro
Roche Moutonee
Glacial striations
Dykes
Glacial Tarn
The Great Stone Chute.
Screes
Headwall

© Richard Kefford         2020         Eorðdraca.         

My books are for sale here:         Richard