The Volcano at Middle Hope

On Thursday 19th April 2018 we went on a field trip to Middle Hope to investigate the volcano there.

We did this in two parts:

The first part was to look at the volcanics on the beach at Swallow Cliff Bay.
The second part was to investigate the volcanics at the Middle Hope Bay further to the East.

The first part has been very well written up by Charley Stamper who, at the time was a student at Bristol so there seems little point in rewriting it so the link to her article on ‘Outcrop’, is here:

http://avonrigsoutcrop.blogspot.co.uk/2013/03/rigs-of-month-march-middle-hope.html

A report on the second part follows on here:
For this part we relied on the directions given in the book, “Geological excursions in the Bristol District” Edited by R.J.G. Savage.
We followed the directions in the book to site 1.3 ‘The Eastern Exposure at ST 3390 6655 at the eastern end of a small bay. There are no pillow lavas here, which indicates that the vent was probably to the West. There is an excellent exposure of the Tuffs as a fault has offset them to the North by a fault that can clearly be seen in South-West corner of the bay.This fault separates the tuffs from the Black Rock Limestones to the West.
I won’t copy out the text from the book, it can be seen on pages 52/3.

Care is required clambering down into the bay to examine the exposures.

This is a very interesting site and, apart from the missing pillow lavas, demonstrates the  volcanic activity very well.

References:

– Faulkner TJ (1989) The early Carboniferous (Courceyan) Middle Hope volcanics of Weston-super-Mare: development and demise of an offshore volcanic high. Proc. Geol. Ass., 100(1), 93-106.

– Volcanic rocks of the Bristol region, Speedyman DL. in Geological excursions in the Bristol District. Savage RJG (1977). University of Bristol.

– OS Sheet 153 Weston-super-Mare and Bleadon Hill © Crown Copyright 2011

– Sedimentary Petrology. Maurice E Tucker © Blackwell science Ltd 1981

– The Coast of the Bristol Region. Quaternary Geology and Geomorphology. David J. Case
Geologists’ Association Guide No. 71. © The Geologists’ Association 2013

– All photos © Charlotte Stamper. 2013

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

The quest for the Golden Spike

Geology is sometimes seen as a boring, stuffy science dominated by scruffy old men with beards – not by me, I hasten to add –  so how about this for a change of image to change and expand your mind?

Geology is the study of the Earth and, as the earth has a long history of some 4.56 billion years, it makes sense to split that long history into chunks – just like English history is split into the Stone age, Bronze age, Jacobean, Tudor, Elizabethan etc. Because geology is international and the same rocks are exposed at different places, in different countries around the world, ages and stages have to be decided internationally. This done by the International Commission on Stratigraphy ( ICS ) – a part of the International Union of Geological Sciences ( IUGS )

Screen Shot 2017-07-03 at 08.16.16

Nearly everyone has heard of  Jurassic, Triassic and Devonian times but the problem is defining the start and length of each of these. These are also split into Epochs which are often called – not always – Upper, Middle and Lower. These are then split into Stages, then Zones and then sub Zones. The transition from each of these to the next is called a point.

For the purposes of this piece we will talk about the point that is at the transition from the Hettangian to the Sinemurian Stage in the Lower Jurassic Epoch, in the Mesozoic Era, in the Phanerozoic Eon. This point has been researched and defined to be 199.3 +/- 0.3 million years ago ( mya ). This defined point is also called a Golden Spike. It is shown as such on the International Stratigraphic chart. It is more fully known as a Global Boundary Stratotype Section and Point ( GSSP )

Screen Shot 2017-07-01 at 12.57.50

I’ll come to how this is worked out later but the problem now is finding a place somewhere in the world that exposes this point. It has to have several attributes: The succession must be exposed, it must be complete – and have several others. Semur-en-Auxois in Eastern France was proposed in 1842 but later research found that the strata was incomplete. Then in 18956-1858 then in 19061 and 1971 the coastal cliffs west of Lyme Regis were proposed. A later study in 1972 and then in 1984 found an exposure on the West Somerset coast that had five times the strata thickness of Lyme Regis. This exceptionally complete sequence, as best exposed north of East Quantoxhead, was proposed as the GSSP for the base of the Sinemurian Stage in 1995. Among the known sections across the Hettangian / Sinemurian boundary elsewhere in the world where sedimentation is believed to be continuous, the GSSP at East Quantoxhead offers the most complete succession of relatively well preserved ammonites. This section meets the requirements of the ICS for a GSSP. It has therefore been accepted as a GSSP by the Sinemurian Boundary Working Group, the ISJS and the ICS – almost unanimously – and was finally ratified by the IUGS in August 2000.

The location of the Golden Spike is described as 0.9 m above the base of bed 145 coinciding with the first appearance of the genera Vermiceras and Metophioceras. These are types of ammonites.

Fig-1-The-main-chronostratigraphic-subdivisions-of-the-Jurassic-System-the

This is the first ever Jurassic Golden Spike in the UK. There have since been others, one in Robin Hoods Bay on the Yorkshire coast and one provisional one on Skye. The complete worldwide list is here.

http://www.stratigraphy.org/gssp/

Going back to how the age of this boundary was worked out:

The Cliff section at East Quantoxhead – and other exposures of the same age around the world contain fossils of ammonites. Ammonites are very useful for establishing comparative dates as they were spread around the ancient world and they evolved at a very fast rate. This means that different ammonite fossils occur in quite precisely known strata. These have all been charted so that a stage change eg Hettangian to Sinemurian in the lower Jurassic can be defined by the evolution of fossils.

This is explained in more detail here

There are, of course, other checks that can be carried out to confirm this. These include: Ostracods, foraminifers, palynomorphs, magnetostratigraphy and gamma ray log.

If you do follow this quest to East Quantoxhead, please keep well clear of the very fragile cliffs as there are often rock falls.

This coast is also a Site of Scientific Interest ( SSSI) so no hammering or fossil collecting from the cliffs is allowed. Please leave this beautiful nature for future generations to enjoy.

If you wish to find out more, I suggest you download the paper by Gert Bloos and Kevin Page ( March 2002 ) Global Stratotype Section and Point for base of the Sinemurian Stage ( Lower Jurassic ) which is freely available on the web.

© Richard Kefford 2020 Eorðdraca

My books are for sale here: Richard

The Iron Mine

This is the report of a geology trip by the Bristol U3A Geology Group to the Providence iron mine at Long Ashton. Long Ashton New Providence Iron Mine Ashton Hill Iron Mine No.2 ST 535 709 New Providence Mine “Mine below Providence Mine. Part choked entrance in pit. 19C red ochre mine. Fine passage with deads and pit props leads to Red Rift with bedding chamber and pool. 2m active micro gour slope, cave pearls and calcited twigs in main passage.” Iron Ore is mainly Hematite,  FeO3 and Red Ochre When the mine was worked out, many miners went to work in the nearby Durnford Limestone Quarry. Iron in the form of hematite and earthy red ochre was mined at Providence Iron Mine, in a field known as the Iron Plantation. Yields varied from 600-3000 tons of ore per annum between 1858 and 1878. Mining continued here until the First World War. Reports from cave explorers in the 1950s refer to an enormous main rift (ST 5350 7093) leading to a partially choked adit entrance (ST 5370 7070) and further workings below. The Miners Rest on Providence originated as a cottage, owned by the BEAMES family, where miners could obtain refreshment. Providence mine also produced Baryte – Barium Sulphate  – Ba SO4 Notes The iron minerals here are in veins in the Hotwells Carboniferous Limestone. This known as part of the Bilbao Supergene Mineralisation . There is a lot of info on this on the Internet. ( Google Bilbao Supergene Mineralisation for more info )The crustal extension in the Early Permian ( C. 290 Ma) to the Late Jurassic ( C. 150Ma ) created rift basins.  This was caused by the crustal relaxation after the Variscan Orogeny, These created more stable platforms between the rift basins. The basins subsided and infilled rapidly with sediment. Basin waters squeezed out onto platforms via tension structures thus allowing mineralised hot waters to flow up into the Triassic sediments, leaving mineral deposits. New Providence Iron mine is in one of these giving rise to localised iron ore sediments.  There is another vein of iron ore shown on the BGS map. Sheet 264. but we saw no sign on the surface that this deposit had been worked. Unlike the lead and zinc ores, many of the iron ore deposits are secondary deposits. Intense weathering of the iron pyrite-rich Coal Measures, and other iron bearing rocks during Permian and Triassic times released the iron into the groundwater. The iron was subsequently redeposited as many thin discontinuous veins of haematite or pyrite, within the Carboniferous Limestone and the Dolomitic Conglomerate, and especially along the unconformity between the two. Many of these pyrite veins have now been altered to form limonite or ochre. Ochre also occurs infilling cavities in the Carboniferous Limestone and Dolomitic Conglomerate, or as a replacement ore-body, where metal-rich ground-waters have chemically replaced the host rock with iron ore. Iron Oxides There are several oxides of iron and each has several polymorphs so iron is a complicated subject. Iron56 is the most common isotope of iron. About 91.754% of all iron is iron-56. … This means that as the Universe ages, more matter is converted into extremely tightly bound nuclei, such as 56Fe. Iron is a “special” element because of its nuclear binding energy. The idea is that when you fuse two light elements together, you get a heavier element plus energy. You can do this up to iron. Similarly, if you have a heavy element that undergoes fission and splits into two lighter elements, you also release energy. Down to iron. The physical reason for this has to do with the balance between nuclear forces and the electromagnetic force. Due to the way these energies work, and because iron is thus thought of as the most stable, if you want to get energy from fusion or fission, your best bet is to use atoms that are farthest away from iron — very light (like hydrogen) or very heavy (like uranium). As a side note, this is also why Type 2 supernovae happen — the star can no longer gain energy from fusion because it can’t fuse past iron, so the outward pressure from energy generation stops and the star collapses.  This will happen to the sun soon – as the sun runs out of hydrogen and starts producing heavier elements until it gets to iron and then fusion will stop and the sun will collapse – in about 5 billion years time. Haematite – Also spelled Hematite. This mineral is one of the most important ores of iron. It can vary in colour from metallic grey to bright red. It is a form of ferric oxide Fe2O3.. It  is the oldest oxide of iron ever to have formed on the earth. Its occurrence is widespread in rocks and soils. It is harder than pure iron. It has been used throughout history as a pigment. It occurs in several forms. Botryoidal or kidney ore, magnetite, iron rose and specularite Goethite   Is a hydroxide of iron that has also been used as a pigment – brown ochre. Its chemical formula is (FeO(OH). It contains iron of ferric form.Its main use is as iron ore and is also the source mineral for yellow ochre. Colour is yellowish to dark brown and black. Most often in botryoidal, reniform, or stalactitic aggregates of radiating crystals or ball-like crystals. Also grainy, in veins, concretionary, oolitic, and in earthy masses. It often assumes the shape of other minerals forming a pseudomorph in place of the original mineral or as a coating above it. It is the main component of rust and bog iron ore. It forms prismatic needle-like crystals ( Needle iron ore ) acicular. Limonite. This a hydrated version of Goethite. It is a component of rust and is yellow to brown in colour. Mined as yellow ochre. eg Winford quarries. Pyrite Iron sulfide FeS2 – fool’s gold. Often found in anoxic, shallow seas. Easily oxidised so specimens often decay. Siderite Iron carbonate FeCO3.  48% iron so a valuable iron ore Glossary for 17th January 2019 Botryoidal / Reniform Texture or mineral habit is one in which the mineral has a globular external form resembling a bunch of grapes as derived from the Greek botruoeidēs. This is a common form for many minerals, particularly haematite, the classically recognized shape. Boxwork Honeycomb pattern of limonite (a mixture of hydrous iron and manganese oxide minerals) that remains in the cavity after a sulfide mineralgrain has dissolved. The boxwork may be spongelike, triangular, pyramidal, diamondlike, or irregular in shape and may be coloured various shades of ochre and orange through dark brown. The colour and shape of the boxwork can sometimes be used to identify the dissolved sulfide minerals Druse Refers to a coating of fine crystals on a rock fracture surface, vein or within a vug or geode. Ferrocrete A form of Calcrete where iron is emplaced instead of calcium Fluting is a process of differential weathering and erosion by which an exposed well-jointed coarse-grained rock such as granite or gneiss, develops a corrugated surface of flutes; especially the formation of small-scale ridges and depressions by wave action. Geode Are geological secondary formation within sedimentary and volcanic rocks. Geodes are hollow, vaguely circular rocks, in which masses of mineral matter (which may include crystals) are secluded. The crystals are formed by the filling of vesicles in volcanic and sub-volcanic rocks by minerals deposited from hydrothermal fluids; or by the dissolution of syn-genetic concretions and partial filling by the same, or other minerals precipitated from water, groundwater or hydrothermal fluids.   Gossan Rust-coloured oxide and hydroxide minerals of iron and manganese that cap an ore deposit. Gossans form by the oxidation of the sulfide minerals in an ore deposit and they thus may be used as clues to the existence of subsurface ore deposits. especially if distinctive boxworks are present. In addition to hydrous oxides of iron and manganese, gold and silver in the native (natural, nearly pure) state and various sulfate, carbonate, and silicate minerals can occur in gossans. The hydrous oxide minerals occur as the residuum when sulfide minerals are dissolved from the outcrops; they are either indigenous (i.e., fixed at the site of the original sulfide mineral) or transported. Indigenous hydrous oxides indicate the presence of copper, whereas transported hydrous oxides indicate its absence or its presence in very low proportion to iron and manganese.  Pseudomorph In mineralogy, a pseudomorph is a mineral or mineral compound that appears in an atypical form (crystal system), resulting from a substitution process in which the appearance and dimensions remain constant, but the original mineral is replaced by another. The name literally means “false form”. Scalloping A sedimentary structure superficially resembling an oscillation ripple mark, and having a concave side that is always oriented toward the top of the bed. Also known as a scallop. Variscan Orogeny A geologic mountain-building event caused by Late Paleozoic continental collision between Euramerica (Laurussia) and Gondwana to form the supercontinent of Pangaea. It is seen in our area as pressure from the South West towards the North East. Vug,  is a small to medium-sized cavity inside rock. It may be formed through a variety of processes. Most commonly, cracks and fissures opened by tectonic activity (folding and faulting) are partially filled by quartzcalcite, and other secondary minerals. Open spaces within ancient collapse breccias are another important source of vugs. Vugs may also form when mineral crystals or fossils inside a rock matrix are later removed through erosion or dissolution processes, leaving behind irregular voids. The inner surfaces of such vugs are often coated with a crystal druse. Fine crystals are often found in vugs where the open space allows the free development of external crystal form. The term vug is not applied to veins and fissures that have become completely filled, but may be applied to any small cavities within such veins. Geodes are a common vug-formed rock, although that term is usually reserved for more rounded crystal-lined cavities in sedimentary rocks and ancient lavas.[2]  © Richard Kefford 2019  Eorðdraca My books are available for sale here:      Richard

Lewisian Gneiss

This is the oldest of my rock samples. It is Lewisian Gneiss from the North West of Scotland. It is about 3,000 million years old – two thirds of the age of the Earth. It can be identified by its colour – usually pink and the intermittent horizontal bands of minerals – usually dark to black.
It is the oldest rock found in the UK and has been through many transformations. It is named after the island of Lewis in the Outer Hebrides.
It was caught up in the Caledian orogeny and so is found in the head walls of the thrust faults of that time.

© Richard Kefford    2020                               Eorðdraca

My books are for sale here:      Richard

West Tanpit Wood

West Tanpit Wood – Lower Failand

A circular walk from St Bartholomew’s Church.

Devonian Portishead Beds – Upper Old Red Sandstone

Devonian Black Nore Sandstone – Lower Old Red Sandstone

Basal Carboniferous Shirehampton Beds – Lower Limestone Shales of the Avon Group

Triassic Mercia Mudstone Marginal Facies – ‘Dolomitic Conglomerate.’

Quarry 

Tufa Dams                 

Springs

Spring line

Unconformity

Carboniferous fossils

Park on the verge outside St Bartholomews, Lower Failand. 

Best map is OS Sheet 154 Bristol West and Portishead.

Enter the field via a stile directly opposite the Tee junction. Walk down the hill, keeping close to the hedge field boundary on your right. At the right hand corner of the field surmount another stile and then walk downhill to a gate under a big tree. After the gate there is another with a wall stretching off to your right for some 50M. Examine closely the stone blocks of which the wall is made. This is quite a coarse sandstone, as a hand lens will show, and also has many clasts of vein quartz included. There are several clues as to what material it is and where it came from. The cross bedding indicates it was laid down in a river – Fluvial sandstone. The grains of sand are polished rather than frosted – so again it is water, not air, borne. The clasts, or pebbles, included in the matrix are of hard quartz but have been eroded so they are rounded or sub rounded, indicating that they have travelled a long distance. There are also some brown pebbles of Jasper. Putting all of this together, it is thought that these pebbles have come a long distance in a powerful river from the North West. Some pebbles have been identified as coming from the Mona complex in Anglesea which is the site of a Pre Cambrian ophiolite, approx. 611 mya – a subduction zone where the ocean sediments of the descending slab are scraped off by the continental plate. This process is known as obduction. There will have been some Andesite extruded above the subduction zone as the entrained seawater heats up as the oceanic slab descends into the deeper, hotter earth.  

This is the Black Nore Sandstone of the Lower Old Red Sandstone. It was probably laid down in the Emsian  Stage of the Devonian Period, 407.6 million to 393.3 million years ago ( mya ). It has minimal fossils in it. The reason for looking at the wall is that there are no exposures or quarries in this strata where it can be seen in situ. The sites of the quarries are surmised but are not definitively known. ( NOTE: See below )

To summarise, volcanic rocks were eroded from the andesitic volcanoes of the Caledonian Orogeny, the mica and feldspar were softer and so were eroded away, leaving the harder quartz grains as the rocks matured. They were transported across a vast desert plain by braided rivers to their present location. The clasts were rounded into pebbles as they were tumbled in the rivers.

Walk to the Eastern end of the wall and then turn left and follow the path. Follow this path to the corner of Summer House Wood. Then walk along the edge of the wood until emerging onto the verge of the A369. Turn sharp left and walk a few yards until there is a footpath entrance on to the tractorway. Follow this until a footpath appears on the left into the wood. Follow this path until the old quarry appears on the left. Climb up to approach the quarry face. BEWARE STEEP DROPS IN THIS AREA. The Angular Unconformity between the dipping Black Nore Sandstone ( Devonian Lower Old Red Sandstone ) and the Dolomitic Conglomerate ( Triassic Mercia Mudstone Marginal Facies ) which rests on it , can clearly be seen. This is a time gap of up to about 200 million years. This unconformity can also be seen on Portishead foreshore and across this region. Have a look at the old building across the stream which used to be occupied by the Rosewell family. It is an old mill, rumoured to be a snuff mill.

Follow the path until a footpath and sign appears on the left. Follow this path up the hill and walk back to the concrete trough. If you look up to the right, you will see a field exposure of the BNS. Walk back up the hill to the BNS wall.

Now follow a hedge back up the hill to the road but this time follow a hedge line heading further to the East, keeping it on your left. Check the capping stones on the top of the wall by the cattle trough – are they all Black Nore Sandstones – without fossils? Look at the drop on the other side of the wall. Was this an old quarry? During the winter, when the leaves are off the hedge plants, a wall can be seen in the middle of the hedge. This wall becomes more distinct as the road at the top of the hill is approached. A close inspection will show that it was built using similar stones that have already been seen. Use the stile to get back on the road where a National Trust interpretation board for the Failand Estate can be seen, close to the hedge.

Directly across the road there is a track with a public footpath sign. Follow this track down a steep hill, passing some cottages on the left. At the bottom of the hill, rejoin Sandy Lane , turning right to follow it down to the ford by Mulberry Farm. The farm house garden wall is partly built on exposed bedrock. These are the Portishead Beds and more exposures will be seen later in the walk. Look at and identify the rocks in the wall. The 1837 tithe map shows a tan yard opposite the farm. It is believed that the tannery was built and run by the St Augustine monks who also created and ran the fishery at Abbots Pool.

Turn right at the Farm and follow the footpath through a gate, keeping the wood and stream on your left. The stream is called Markham Brook. It flows into the River Avon at Pill. Go through a gate into the wood. Just in front of you is a bridge across the stream. Cross the bridge, to the left a small pump house can be seen. A look inside will show the pump housing while in the side of the stream an iron pipe can be seen. This worked on the hydraulic ram principle. The pressure in the pipe from higher up in the stream increased until it was high enough to trigger the ram with an audible thump – thus pumping water up the hill to a storage tank near to where it was needed. One of these tanks can be seen by the side of the road on the way back to the church. The use of this water supply to Lower Failand continued until the 1950’s. The tile on the top of the pump house is embossed with ‘Danger. Baldwin. Electricity’ so assumedly the pump was converted from a hydraulic ram to an electric pump at some stage.

Follow the stream until you see a second bridge. Cross this bridge, turn to the right and follow a path along a gully until a fallen tree can be seen. Look to the right at the stream and look for a tufa dam in the stream. The water has passed through the limestone, dissolving carbonate minerals. Where it passes over a cascade, carbon dioxide is released. The minerals come out of solution and are deposited as carbonate rock. This slowly builds up to form a tufa dam. This is a similar way that stalactites are formed in Limestone caves and stromatolites in shallow warm seas. These are relatively rare features in the UK so please do not disturb this example in any way. A separate, more detailed explanation, is in the appendix.

West Tan Pit Wood is so called because leather was tanned using the clean water. Pits were dug and lined with oak and used for leather tanning. The tannins leached from the oak bark to soften the hides.

Return to the bridge and walk on to a ’Tee’ junction with another path, noting the sandstone crag exposure to your right. These are Upper Old Red Sandstones from the Devonian period and are known as the Portishead Beds. These are younger than the Black Nore Sandstones previously seen. The also have a different habit in that there are minimal pebble inclusions and the cross bedding is more defined. These deposits were laid down during the Famennian stage of the Upper Devonian period 372.2 to 358.9 million years ago Subtracting the end of the Emsian stage, 393.3,  from the start of the Famennian, 372.2, you get a gap of about 21 million years. During this time either nothing was deposited or something was deposited and then was subsequently eroded away. Either way, there is a time gap between the two strata, this is called an unconformity.

Turn right on to the other path, noting the carved wooden sign. Follow the path to a gate which allows entrance to a grassy area with an artificial circular pond A rest may be taken on a thoughtfully provided seat to enjoy the pool with its backdrop of a small cliff of the sandstone. Walk further on, taking the right hand fork across the grass to see a natural-looking pool with no apparent water supply, even though water is flowing out. It may be fed through a hidden pipe from the spring-fed stream in the garden. This is one of the springs and is flowing out of the Limestone overlying the Sandstone. The Limestone is permeable because of the many joints so the water can flow through it but cannot enter the impermeable Lower Limestone Shales of the Avon Group so emerges at the surface as a spring and runs downhill as a stream.

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 Tufa dams

Follow the path up a steep incline to a path junction at the end of the road, in front of a large garage. The two houses there are called Ferney Row. 

Progress up the hill then turn right and cross the field, keeping the hedge on your left. A gate into a wood will appear. Pass through the gate, which may be surrounded by deep mud and follow the track noting the springs on the hillside to your left and and the rock in the track bed. This is the limestone which rests conformably on the Devonian Sandstone. This is Carboniferous Limestone – Lower Limestone Shales from the Avon Group. This is younger than the Devonian Sandstones. As its name implies, this was laid down in the Carboniferous period, in fact it is the basal strata of the Carboniferous succession. At the beginning of the Carboniferous – approx. 360 mya – the arid terrestrial environment of the Devonian gave way to shallow marine conditions – a marine transgression. The Mendip area became part of a broad, southward shelving, shallow tropical sea that stretched from Belgium westwards into Pembrokeshire. The initial flooding of the region produced the mud-rich Avon Group (Lower Limestone Shale), This is up to 150 m thick in the western Mendips. The dominant lithology is fissile mudstone with limestone inter-beds. The mud-rich nature of the succession reflects the environmental transition from arid desert to shallow sea. Conditions were too turbid to allow the growth of corals, which are a feature of much of the lower Carboniferous succession, but other marine fossils such as crinoids, brachiopods and bryozoans became well-established and are a significant component of limestones in the lower part of the succession, including a marker-horizon known as the ‘Bryozoa Bed’. Ripples, scours and cross-bedding in the limestones show that deposition occurred in a shallow, high energy environment, and some of the limestones are distinctly reddened due to high concentrations of the iron mineral haematite. The higher part of the formation contains greenish-grey shales and black crinoidal limestones, which were probably deposited in a slightly more open-water marine setting.

DSC00023 (1)

Crinoid ossicles in Avon Goup Lower Limestone Shales

Keep an eye on the verges and the track bed, you will be very unlucky if you do not see some brachiopod and Crinoid fossils there. Possibly, if you are lucky, some Bryzoa.. The dip of the strata may be seen in the track bed.

Continue along the lane, pass a wooden bungalow on your right and eventually arrive at Oxhouse Lane complete with the Forestry Commission Wood notice board. Turn to the right and follow the lane back up to the church. Just after leaving the track, you will see on the right an exposure of the Portishead beds showing that this is very close to the contact between the Limestone and Sandstone – hence the springs in this area. The road will lead you up the hill. Halfway up the hill, look back to the hill on the other side of the valley and the road to the wood. You will see a ridge running across the field. This is called a break of slope and marks the transition to the harder Black Rock Limestone from the softer Lower Limestone Shales. The harder and softer rocks are eroded at different rates so forming the ridge. This is called differential erosion. Just before you reach a footpath off the the right, you may be able to see another small pump house hidden in a patch of woodland. When passing Failand House to your right, an inspection of the gate posts will reveal that they are made from Black Nore Sandstone. The house is owned by the National Trust but there is no public access. 

Arriving back outside St Batholomew’s Church, it is worth having a look at the building stones. The church was built by Richard Vaughan in 1887. The areas that require freestones – window frames, statue niches etc. are made from Bath Stone. This is a cream Oolitic limestone from the Great or Inferior Oolite, probably from one of the quarries on Dundry Hill. The walls are built from the local Black Nore Sandstone, the pebbles can clearly be seen. The colour of the walls also hints at the Old Red Sandstone. Inside, the font is also made from Bath stone. The steeple can be seen to be cream rather than red so is probably made from Bath stone as the individual blocks would need to have been shaped during the building process.

It is always worth looking at churches, from the geological point of view, as they were usually built mainly from the closest available suitable stone to reduce costs. Transport was more expensive than the quarrying costs. They are therefore a marker for the quarries and rock to be found locally.

There is a booklet, available for 10p at the church or a web site – see appendix1 at the end of the booklet.

It is also interesting to see that the churchyard is bounded by a wall made from the same Devonian stone. However this wall is topped by a different sandstone. This is the Pennant Sandstone from the Carboniferous period. This gives a delightful colour contrast to the main mass of the boundary wall.

© Richard Kefford    2020                               Eorðdraca

My books are for sale here:      Richard

The Clapton Klippen

Photo credit  Mark Howson

Upper left  –  Sigillaria
Right           –  Calamites
Lower left  –  Lepidodendron

It was a mizzly sort of day but, as daft geologists, we decided to go anyway. We met at the agreed time under the motorway bridge. It was dry there, except for the rivulets running down the gutters on each side of the road. It was also dark so ferreting out our gear from the car boot was mostly feeling for the oh so familiar objects.

We dressed up for cold, wet weather and muddy ground, secured the cars and then set off up the familiar road which quickly morphed into a track. At the branch, we headed left through a kissing gate onto a rocky path that hugged the higher side of the field, up against the barbed wire that kept us out of the wood that was groaning in the erratic wind. The path was muddy with many rocks intruding through the red mud, their curiosity driving them up into the damp air above . We had a look at these rocks and speculated about their provenance. We identified them as Pennant Sandstone from the Carboniferous but why were they so separate instead of just being a massive exposure? Was there a quarry nearby ? Perhaps this was the discarded waste from the quarry that was graded as poor quality?

We came to another gate that led us uphill into the wood. It was a public path through private woodland that permission is required to visit, so we had asked for ,and were given, permission to divert from the path as we thought fit, to investigate any quarries or interesting whatevers that we spotted. The path curved to the left and we could see an outcrop over to the right. This was a valley curving away to the North about 5 metres deep and 10 metres wide at its crest. On the Southern side it was steep with several near vertical cliffs that looked like old quarry faces. Close inspection showed that the rock was Pennant Sandstone. We were now higher than the footpath along the edge of the wood so this tended to confirm our hypothesis that the questing stones we had seen on the footpath were indeed from a quarry – this one? Perhaps as surface treatment for a muddy path?

We started looking along the opposite side from the face as stone that was discarded was usually dumped away from the active face. We knew that the Pennant was usually  quarried for building and was prized for its prized ‘flats’. Any fossils were regarded with suspicion as “the devil’s work” or because they broke up the smooth style of the rock and reduced its quality as building stone. This was something we had learned – when looking for fossils in a disused quarry, always look for the rejected stone pile – unless, of course, the quarry is for road-stone, which is destined to be crushed and screened anyway so any fossils will have been destroyed in the process.

We found a ring of charred wood and rocks which had been clearly gathered for a fire – perhaps a barbecue? We started sorting through the stones and found an interesting rock with two fossils in it. We were delighted as my companion – a geologist – had found a Sigillaria specimen here a few weeks before. Just after we found this, a couple turned up from the local Court. We had invited them to join us on the fossil hunt. They told us that their house, near the top of the hill was built from Pennant Sandstone – most likely from this quarry. They had brought the previously found Sigillaria fossil as they wanted to bring it back and leave it at its birthplace.

We spent another half an hour or so looking for more fossils but it was not to be so, after many photos we carefully hid the fossils in a cleft in the old quarry face for others to find. There wasn’t much else to see as it is a small quarry. I would like to stress again that it is on private land and permission should be sought from the owner before entering it.

We then looked around the area because we were looking for the variously named Clevedon or Naish House fault as we knew it ran from Clevedon beach West along and through this area. We found clues – a change from woodland to a field used for grazing sheep above the quarry. As we walked up to the wire fence between the two, we found an increasing density of limestone rocks. These rocks had crinoid fossils in so were probably either from the Avon Group, Lower Limestone Shales or from the Black Rock Limestone. This demonstrated that the fault was in this area. The vegetation change from woodland to grazing fields followed the underlying geology change from acid to alkaline soil

It was now time to retrace our steps to the motorway bridge and  then walk along the side of the motorway towards Nicholas Wood which is a wood perched on a large, almost circular, mound. This one of the Clapton Klippen. Klippen is a plural German word that translated to the English, Cliffs. A Klippe is a peculiar feature where older rocks have been moved by faulting and erosion. The Oxford Dictionary of Earth Sciences defines it thus: A tectonic outlier produced by the erosion or gravity-gliding of one or more nappes. The front portions of the nappes become detached to produce the klippe structure. A nappe is defined as: from the French nappe, meaning ‘cover’ a thrusted mass or folded body in which the fold limbs and axes are approximately horizontal.

So this means that, as you approach Nicholas Wood and transition from a grazing meadow to wood land, you walk up a hill from a muddy red field into a dry ground wood. Rock clasts are randomly scattered on the surface and can clearly be seen to be Black Rock Limestone complete with Crinoid fossil ossicles.

Nicholas Wood covers just one of the Clapton Klippen. There are four others in the area – one of which has been quarried for its limestone. We debouched on to St Michael’s church path and walked back through the village then up Wood Lane to the cars.

The other Klippen will be investigated another day.

© Richard Kefford    2020                               Eorðdraca

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