Becoming a STEM Ambassador

I had been thinking of becoming a STEM Ambassador for a while and I finally took the bull-by-the-horns in January 2020; maybe the turn of a new decade was the final push that got me motivated?

What does STEM stand for and what does it relate to?

STEM in an abbreviation of Science, Technology, Engineering & Mathematics. So what?

The relevant point to make is that the UK government has identified a shortage of science graduates entering the jobs market. That shortage will filter through to the national economy leading to a degradation of the capacity of the UK to maintain its pre-eminence as a world leader in innovation. The reason for the shortage in science graduations is contentious and can range between a lack of government funding & support for science degrees and to science in further education to the perception that science is nerdy and dull. It certainly isn’t, as it provided me with fantastic opportunities to travel the world, see fantastic things and spend time living in diverse cultures & meet wonderful people.

So, what is a STEM Ambassador?

STEM Ambassadors are volunteers from a wide range of science, technology, engineering and mathematics related jobs and disciplines across the UK. They offer their time and enthusiasm to help bring STEM subjects to life and demonstrate the value of them in life and careers.

STEM Ambassadors volunteer their time as a resource for teachers and others to engage with young people inside and out of the classroom. STEM Ambassadors bring fresh inspiration to young people and present themselves as positive role models to school children as people that gain great enjoyment and fun from their jobs in STEM.

A dropping trend has been identified in teenagers in-regards to their interest in STEM subjects in general. Although both find STEM subjects interesting in the early teenage years their interest drops significantly as they approach adulthood and is the case for both Boys and Girls.

Percentage Interest in STEM subjects through the Teenage Years

The Process of becoming an Ambassador

The process of becoming a STEM Ambassador is relatively straight forward. It is voluntary and requires the individual to be motivated to volunteer.

Summary of how to become an Ambassador

It begins with registering your interest via the STEM Ambassador website (URL provided below), completion of your Profile on the website and connection with your regional STEM hub (Wales, East Scotland, Southwest of England, Northeast of England etc.

Once registered you will attend a 2-hour induction session at a venue close to your home location where you will learn about the philosophy, intention and methods of the STEM Ambassador programme. During the induction programme you will need to provide some items of identification (Passport, Driving License etc etc) from which a (free of charge) DBS check of your details will be undertaken. This check is performed as the majority of your voluntary work will involve interaction with children of all ages.

Once the DBS is completed and passed you will receive a certificate that identifies you as a STEM Ambassador. From that point onwards you can attend careers and education events organised by Schools and Further Education Colleges.

What is expected of a STEM Ambassador?

Events within your geographical area of operation (defined by you) are posted on the STEM Ambassador hub from which you can elect to attend. The education institution is notified of your interest and will confirm or decline your attendance.

The expectation of a STEM Ambassador is to enthuse school children with the joy that STEM subjects bring and in doing so stimulate the children’s passion and involvement with STEM subjects that may lead to life-long careers in STEM subjects. Hopefully the Ambassador will demonstrate that Science, Technology, Engineering and Mathematics subjects are not boring, are not nerdy, are fascinating, are well-paid and can lead to travel and excitement but most importantly to fulfilled careers.

Benefits of STEM Ambassadors

The benefits to the Ambassador include a feeling of reward in giving something back to a family of disciplines that have provided the Ambassador with a fulfilled career and a sense of achievement in seeing young-people take-up STEM subjects.

Two lovely Indonesian ladies and A Brave New World

I recently had the great pleasure of leading a pair of lovely mother and daughter from Jakarta, Indonesia to various locations on the Heritage Coastline of South Wales. The mother was visiting her daughter who is studying a university degree in the UK. They became aware of South Wales Geotours from its online footprint. We were extremely fortunate with the weather and in-fact it would appear we went out on the very last day of the Summer of 2019!! And we were not the only ones making the most of the weather because we were joined at our first locality by a film crew from Netflix; but more on that later.

Fig 1. Setting the scene at the Geological information display, Southerndown (Photo: South Wales GeoTours)

We started-off at the glorious bay of Southerndown (Figure 1) where the Lower Jurassic Porthkerry formation is exposed in the spectacular cliffs. By the Early Jurassic (200-180 Million Years Ago) the rifting-apart of the Laurussia Plate had progressed to such an extent that shallow seas had started to flood into/onto the Pangaea continent as it started to break-up. What was to become the U.K., consisted of a number of islands surrounded by warm, tropical seas.

Of special interest to geologists is the regular alternation of light grey limestones with softer, dark grey mudstones (Figure 2) on the scale of tens of centimetres. This regular alternation accumulates to a thickness of up to 120m in places but more generally 50-60m in the cliffs at Southerndown, with individual units extending laterally for many miles. This implies that the rocks were deposited in a an extensive and relatively stable depositional setting.

Fig 2. Regular alternations of light-coloured limestone & darker mudstone of the Porthkerry Formation (Photo: South Wales GeoTours)

There are two alternative explanations as to the cause of this repeated alternations, one being that it is the result of sea-level changes influencing water depth and hence sedimentation and secondly, that it is the product of secondary alteration of the original sediment. I think the consensus now is that the repetition is the product of climatic and sea-level fluctuations caused by variations in the orbit and attitude of the Earth as it moves around the Sun (eccentricity, tilt and precession). These cycles were first identified by Serbian astronomer Milutin Milankovitch in 1920 and operate on tens of thousands of years duration.

The theory essentially runs as follows: as the earth orbits the Sun in a non-circular way (in-fact an elliptical orbit) when the Earth is further away from the Sun it receives less insolation and is therefore colder. During these colder periods the polar ice caps increase in size and lower sea-level. When the Earth is closer to the Sun the Earth receives more solar radiation and becomes hotter. When its hotter the ice caps melt and sea-level rises. When sea-levels are higher there is less land to suffer erosion and the resultant sediment is dominated by very fine-grained muds, whereas when sea-levels are lower sediment structure is coarser-grained. Thus the black mudstones of the Porthkerry Formation were deposited when the Earth was closer to the Sun and the limestones when the Earth was far from the Sun. Because there are many alternations of mudstone and limestone exposed in the cliffs, they represent many cycles and thus must have been deposited over many millions of years.

The Porthkerry Formation is also affected by abundant faulting and jointing formed during the movement of the Earths tectonic plates. At one locality a fault is very clearly exposed offsetting the alternating layers of the Porthkerry Formation, admittedly with only about a metre of offset from one side to the other. The line of the fault traced in the cliff can be seen extending out through the wave cut platform at the base of the cliff (Figure 3) which allows one to visualise the 3-dimensional shape of the fault.

Fig 3. Fault plane exposed in cliff at Southerndown (Photo: South Wales GeoTours)

The rocks are also shot-through with lots and lots of factures that probably formed during the flexural relaxation of the Crust after tectonic collision. There is essentially no offset across the fracture which is an essential difference between faults and fractures. Fractures are natural cracks in the rock. Much like the fault described above the fractures can be seen in 3-dimensions, extending from the vertical cliffs and into the horizontal platform at sea-level. These cracks together with the alternating layers leads to the cliffs being very unstable. The fractures in the wave-cut platform result in the limestone eroding into blocks that resemble row after row of loaves of bread just taken out of the oven (Figure 4).

Fig 4. Fractures can be traced from the cliff face into and along the beach (Photo: South Wales GeoTours)

The rocks of the Early Jurassic also exhibit some fantastic palaeontology too; with crinoids (sea-lillies), echinoderms (sea-urchins), corals, ancient oysters and cockle-like shells and the classic ammonites being common. Trace fossils, such as feeding burrows left behind by small invertebrate organisms such as worms and crustaceans are visible in much of the Jurassic rock. In a similar way there are some world-class examples of faulting and jointing affecting the rocks.

So how does Netflix fit into our story? Well, the lower car park at Southerndown was closed on the day which surprised us greatly. It turned out that a large film crew was filming a new Netflix production of Aldous Huxley’s most famous novel “A Brave New World” at Southerndown due for release in 2020, The car park was full of television crew lorries and vans brimming over with cables, cameras and lots of other TV paraphernalia and a large catering tent was set-up too. The filming was taking place up on the cliff top.

Fig 5. Netflix film crew on cliff-top with their lorries filling the car park (Photo: South Wales GeoTours)

I managed to walk up the cliff side to see how close I could get to the action. Glad to say I got pretty close. I saw a lot of activity but I didn’t see any famous actors unfortunately, not that I’d notice them if I did.

Fig 6. Close-up of the film crew in action (Photo: South Wales GeoTours)

After Southerndown we moved on to an area just to the east of Barry Docks. Here the geology is very different and consists of late Triassic rocks that are older than the Lower Jurassic rocks at Southerndown. The Late Triassic Branscombe Mudstone Formation (Figure 5) ranges in age between 228-208 million years old and is formed of red mudstones and thin sandstone and pebbly units reflecting deposition in a Sabkha environment adjacent to a body of standing water surrounded by soft sticky mud and which periodically became covered by windblown dust. The climate was arid and hot much like the Middle East today.

Fig 7. Triassic desert sandstones & mudstones exposed near Barry (Photo: South Wales GeoTours)

The rocks were deposited in the interior of the Supercontinent known as Pangaea (when all the landmasses of the earth were grouped into one single mega-continent). At the locality numerous footprints of early Dinosaurs can be found (Figure 6); it may take a bit of time for you to get your eye in to see the footprints but when you have found one or two you soon get to see many more. It’s likely that the animals walked through the soggy wet mud at the edge of a lake to get to the water to drink; as they walked the mud oozed-up between the toes and feet of the Dinosaurs with the prints quickly drying-out in the hot sun. Alternatively, the prints may have become covered by windblown dust which hardened into rock. These alternate ways of preserving the footprints is important as sometimes the footprints are seen as downward impressions whereas others stand proud of the background rock. They stand proud because the (windblown or water laid) sediment that in-filled the original tracks turned into rock harder than the original rock around it.

Fig 8. Dinosaur footprints exposed near Barry (Photo: South Wales GeoTours)

And it’s not just one species of Dinosaur that left footprints; just like today if animals come to drink at watering holes they are hunted by predators. There are many small 3-toed footprints (Figure 7) most probably left by agile carnivorous Dinosaurs such as the Therapod, Coelophysis together with larger generally rounded 4-toed footprints of larger plant-eating Sauropod Dinosaurs such as Plateosaurus. It is amazing but you can clearly see the shape of the individual toes (Figure 7) together with the mud squeezed out between them and in other places an elevated rim of mud (now rock) around the more rounded 4-toed prints, left from 220 million years ago!!

Fig 9. The Ladies were fascinated with the Dinosaur footprints (Photo: South Wales GeoTours)


Scouting Trip for Fossils

All the rocks exposed along the Heritage Coastline of South Wales contain evidence of past life, namely fossils and trace fossils, of one form or another. The oldest rocks that we can see in the area are from Early Carboniferous Epoch (circa 340 Ma) ranging through the Triassic Period (252-201 Ma), to Early Jurassic (190Ma).

Preserved life-forms range from sea-lilies (Crinoids) and corals indicative of reef systems in the Early Carboniferous Limestone to sea-shells (Chlamys), oysters (Liostrea) in the upper units of the Triassic rocks. But importantly, the Triassic was the Period when Dinosaurs began to evolve and a number of instances of the evidence of Dinosaurs have been found in the Triassic rocks of South Wales.

A (relatively) minor global Mass Extinction event happen towards the end of the Triassic (205 Ma) that held-up the recovery of life after the biggest ever Mass Extinction event in Earth history at the end or the Permian Period, 255 Million years ago.

Chronology of Mass Extinctions. Acknowledgement to Samuel Scriven 2016

Life-forms are very rare to find in the very Earliest Jurassic, or at least that has always been thought to be the case, before life recovered in the later Early Jurassic. The first occurrence of the Ammonite Psiloceras planorbis is used to confirm that rocks are from the Jurassic Period.

Fossilised bones of Ichthyosaurs and Plesiosaurs (the Loch Ness Monster is thought to be a Plesiosaur) have been found in the area and it is worthwhile to highlight that the rocks between Southerndown and Llantwit Major are of a similar same age as those found on the Jurassic Coast of southern England; I refer you to the recent David Attenborough BBC programme about the giant Ichthyosaur found near Lyme Regis in Dorset.

The oldest rocks we will see are the Early Carboniferous Limestones that were formed in warm, tropical seas when Britain was located between 2° and 8° N of the paleo-equator, roughly equivalent to the Bahamas of today. Limestone is formed in a number of ways; firstly, by the accumulation of tiny crystals of Calcium Carbonate either derived from eroded shells or from the precipitation of Calcium Carbonate directly from seawater and secondly, by the accumulation of the hard, protective outer casings of soft-bodied organisms namely corals and shells. These hard parts are also formed by the capture of Calcium Carbonate from the seawater by the organisms.

The carboniferous Limestone can be seen at Porthcawl and Ogmore. Technically, Porthcawl is outside of the Heritage Coast but it does have good outcrops and is easily accessed from ample car parking facilities. Unfortunately, it is a problematic place to get to as it is on the western side of the Ogmore estuary and requires a 20-minute drive around the estuary to access the outcrop. The Carboniferous limestone however can also be seen at Ogmore (which is located on the “same-side of the river” as the rest of the Heritage Coast outcrops and where there is ample car parking and easy access to the outcrops. Crinoids (sea-lilies) and corals can be found preserved in the limestone.

Rocks of the Permian Period are absent in South Wales; the Permian was the period following the Variscan Orogeny when all of Britain was a desert landscape with intense erosion.

The majority of Triassic aged rocks in South Wales although present do not contain much evidence of life other than limited pollen and spores. Environmental conditions continued to be very difficult for life to get established in the deserts and hyper-saline lakes indicated by the abundant gypsum (evaporate salt) bands. However, as the supercontinent of Pangaea began to rift-apart seawater began to flood the arid environment and fossils can be found in the uppermost Triassic rocks (the Penarth Group).

The best place to find Triassic fossils is between Penarth and Lavernock. These localities are easy to drive to but, parking is limited and walking along the beach can be difficult because of the loose boulders and is best suited to those that are fit, without ankle or knee problems. It is thought that sea depths were shallow as many of the sandstone and limestone beds show fossilised ripples. In these beds abundant Liostrea (ancient oysters) and Chlamys bi-valves (ancient cockle-like shells) can be found in many of the fallen blocks on the beach. In-places fossil bones and teeth belonging to reptiles can be found in what is known as “the bone bed.”

Liostrea in Late Triassic limestone

Although the Jurassic is the most well-known geological Period with regards dinosaurs, it was in the Triassic that they began to evolve and diversify. And Triassic aged dinosaurs have been found in South Wales. As far back as the 1950’s fossil remains of a small, Iguana-like dinosaur named Clevosaurus were found in a quarry in the Vale of Glamorgan LINK. The not-uncommon bones that can be found in late Triassic rocks where we visit may be of such a dinosaur.

Representation of Triassic reptile Clevosaurus

An exceptional indicator that dinosaurs were spreading their range in the Late Triassic can be found in the presence of multiple dinosaur foot-print tracks near Barry. Although not being a fossilised fragment of the dinosaur itself the tracks can provide geologists with vital information about the size and weight of the animal and whether it walked on two feet or four. Foot-prints, burrows and feeding trails are called Trace Fossils as they indicate the presence of an animal but are not part of the animal. The study of Trace Fossils is a separate area of geology known as Ichnology.

At the location (LINK to Blog 9) it appears that a number of different species of dinosaur left footprints in the soft mud at the time that probably fringed a temporary lake within the desert environment. The smaller prints probably were made by a small predatory Therapod dinosaur (walked on two feet) such as Coelophysis. There are also larger four-toed prints that suggest they were made by a large Sauraopod dinosaur (walked on all fours) such as Plateosaurus.

As you walk westwards from Penarth to Lavernock the rocks become younger and at one point the boundary between the Triassic and the Jurassic can be seen. The earliest Jurassic was always thought to be devoid of life following the end Triassic Mass Extinction event but in 2014 an almost complete skeleton of a small velociraptor-like dinosaur was found a meter or so above the boundary at Lavernock. This fossil is the oldest Jurassic dinosaur yet found in the U.K. and has been named Dracoraptor hanigani meaning Dragon Thief. It is obvious that if one specimen can be found then there may be others close by waiting to be found.

It seems that life in the open oceans began to increase and diversify during the Early Jurassic. A number of different species of Ammonite can be found in the regularly alternating limestones and mudstones of the Porthkerry formation, most commonly Psiloceras planorbis.

Early Jurassic Ammonite, Psiloceras planorbis

Ammonites have a coiled, disc-like shell that is segmented into a number of chambers to help the animal float in the sea. The animal itself, which is similar to modern day Cephalopods such as squid, lived in the first chamber nearest the aperture and it moved around by pumping seawater out of a tube set within the tentacles. It probably fed on small fish and plankton.

Other Early Jurassic fossils that can be found in the rocks exposed between Southerndown and Nash Point include ancient sea urchins (Echinoids) plus a number of different types of bi-valves (meaning two shells such as modern-day cockles) such as Plagiostoma and nests of Gryphaea better known as Devils toenails. It has also been known to find the remains of Ichthyosaurs and Plesiosaurs in the rocks of the Porthkerry Formation so keep an eye open for them!

Trace fossils can also be found at Southerndown that mark the burrows of ancient works or prawns as they moved through the soft-sediment on the ancient Early Jurassic seafloor.

It is obvious that a whole variety of exciting fossils and trace fossils can be found when out walking along the seashore of the Heritage Coast ranging from fossil corals and sea-liliesin the Limestones of the Carboniferous, through sea-shells and possibly dinosaur bones and footprintsin the late Triassic rocks, to Ammonites, Devils toenails and even Ichthyosaurs & Plesiosaursin the youngest rocks.

Early Jurassic Scouting Trip

By the Early Jurassic (200-180 Million Years Ago) the rifting-apart of the Laurussia Plate had progressed to such an extent that what was to become the U.K. consisted of a number of islands surrounded by warm, tropical seas. To the west and north of the U.K. the proto-Atlantic was rapidly opening and to the northeast the failed rift system of the North Sea was forming. The Tethyan ocean was located 400 miles to the southeast of the proto-U.K.

Following the Mass Extinction event (synchronous with the Rhaetian Transgression) close to the end of the Triassic Period the earliest Jurassic (known to geologists as the Hettangian Stage) rocks were thought to be completely devoid of fossils. However, in 2014 a number of fossilised bones were found within a metre above of the Triassic/Jurassic boundary and below what was previously thought to be the first occurrence of new life in the Jurassic, the ammonite Psiloceras planorbis.

The newly discovered bones were of a previously unknown early Dinosaur that has been named Dracoraptor hanigani, meaning Dragon Thief and is the oldest Jurassic dinosaur yet found in the UK. It is thought that the fossil found was a juvenile about 3m long and a carnivore related to the much younger (Cretaceous-aged) T.Rex. Although Dracoraptor lived on land it was found in marine rocks meaning that it must have floated offshore a while after dying, and prior to being buried by sediment at the bottom of the sea.

Artists Impression of Dracoraptor

The Triassic/Jurassic boundary is exposed in the cliffs between Lavernock and Penarth which is a classic, world famous location for Geologists. Although parking is available for about 4 cars at Lavernock unfortunately this is not an easy location to get down to or walk about at as the beach is formed of large, loose boulders and cobbles that are also covered with seaweed in many places. The probability of losing one’s balance and slipping is high, so it is not a preferred location for people with unstable knees or ankles to visit. However, it has some great geology!!

Very earliest Jurassic rocks

Immediately to the west of Lavernock Point is St. Marys Well Bay and this too is a fantastic location to understand the geology of the area. The full succession (a three-way split) of Early Jurassic rocks is exposed in the cliff face and you can see how the geology evolved through time. It also has some great structural geology. But once again access is via Lavernock Point which has difficult beach conditions.

It is the uppermost (youngest) of the three separate parts of the Early Jurassic, known as the Porthkerry Formation, that forms the spectacular cliffs of the Heritage Coast of South Wales. These cliffs can be seen at places such as Nash Point and Southerndown. Access to Nash Point by car isn’t easy as it is found by driving along twisty, single-track roads. Parking is available on the cliff top at a private car park. The well-known Nash Point lighthouse is located near-by which has a visitor centre and where weddings can be held.

Porthkerry formation exposed in the Spectacular cliif at Nash Point

Southerndown is probably an easier location to get to by car as the quality of the roads are better and it is better signposted. Car parks are located at the cliff top and at the bottom of the cliffs immediately adjacent to the beach. This latter car park is ideally suited to our trip, but it is a very popular tourist attraction and the car park gets full very early on in the day.

Of special interest to geologists is the regular alternation of light grey limestones with softer, dark grey mudstones on the scale of tens of centimetres. This regular alternation accumulates to a thickness of up to 120m in places and the units extend laterally for many miles. There are two alternative explanations as to the cause of this repeated alternations, one being that it is the result of sea-level changes influencing water depth and hence sedimentation and secondly, that it is the product of secondary alteration of the original sediment.

I think the consensus now is that the repetition is the product of climatic and sea-level fluctuations caused by variations in the orbit and attitude of the Earth as it moves around the Sun (eccentricity, tilt and precession). These cycles were first identified by Serbian astronomer Milutin Milankovitch in 1920.

The rocks of the Early Jurassic also exhibit some fantastic palaeontology too; with crinoids (sea-lillies), echinoderms (sea-urchins), corals, ancient oysters and cockle-like shells and the classic ammonites being common. Trace fossils, such as feeding burrows left behind by small invertebrate organisms such as worms and crustaceans are visible in much of the Jurassic rock. In a similar way there are some world-class examples of faulting and jointing affecting the rocks.

Fossilised Jurassic work burrow

Triassic Scouting Trips

The Triassic age rocks (250–201 Million years ago) lie unconformably on the Carboniferous Limestone; there is a large time gap between the end of the Limestone and the deposition of the first Triassic rocks and, in places, the Triassic rests with physical discordance on the Carboniferous Limestone.

At this time the U.K. was situated at about 40°N within the Laurussia Plate that formed one part of the Pangaea super-continent. Environmental conditions were essentially desert-like, much like large parts of the Middle East and central Australia today (Fig. 1). In such areas sedimentation is characterised by the erosion of wadi systems in which coarse grained pebble beds are deposited and, by the deposition of fine-grained windblown dust and mudstones. Sabkha evaporate bands are frequent the result of evaporation of occasional lakes following heavy rains.

Fig 1. Lake Eyre, Australia. A modern analogue for Triassic environments

The Triassic rocks are exposed widely across South Wales. At Ogmore there are some isolated spots where you can clearly see where the underlying Carboniferous Limestone has been sharply channelized (Fig. 2) in a similar way that modern Wadi systems in deserts today. The wadi can form in a very short time and gets filled by the basically the same jumble of rocks that helped cut the wadi in the first place. Parking facilities are good and access can be made via the beach at low tide.

Fig 2. Triassic Wadi (to the right) cutting through Carboniferous limestone (to the left)

Further east in the Vale of Glamorgan at Barry and Penarth for example, the Triassic rocks are much finer-grained red and green mudstones with numerous pink and white gypsum bands (Fig. 3). These rocks were deposited as mud layers on the edge of a lake in an arid environment.

Fig 3. Alternating oxic and anoxic playa lake and sabkha deposits exposed at Barry Island

Barry is an ideal location as even at high tide the cliff exposures are not covered by the tide and access is easy via the beach. There is also ample parking and hospitality facilities at Barry. Another location where the Triassic rocks can be seen is at Beachley however, this outcrop can only be accessed at low tide and even then, is quite unsafe because of slippery rocks underfoot. This leads me to decide not to take people on trips to Beachley except at Spring low tides.

By the time of the latest Triassic rifting of Pangaea had progressed to such a point that shallow seas were beginning to flood across the former desert landscape (known as the Rhaetian Transgression). Low-lying areas naturally flooded first leading to the creation of numerous islands from the higher ground areas. Living on these islands were small Iguana-like dinosaurs named Clevosaurus the fossilised remains of which have been found in a quarry further north in the Vale of Glamorgan LINK to Blog 12. At first these seas were brackish with numerous shelly animals living on the sea bed but as sea levels rose more open-marine conditions prevailed leading deposition of deeper water mudstones with open-marine animals such as Ammonites being favoured.

The latest Triassic is marked by a large Mass Extinction event, the cause of which is not known with any real understanding.  The Triassic/Jurassic boundary is exposed at Lavernock and in the cliffs towards Penarth but the beach there consists of numerous large boulders and cobbles meaning that walking along the beach is sometimes difficult. Also, the beach and access to much of the shoreline is not possible at high tide and even at low tide the rocks are covered in slippery seaweed.

Bespoke Field Trip for UWC Atlantic College

Very early in April I had the great pleasure of leading a group of 8-9 staff members of UWC Atlantic College (based at St. Donats) to a number of locations on the coast of the Vale of Glamorgan in order for them to understand in greater depth the landscape of the area in which the college is based. Although it being early Spring the weather was glorious and perfect for field work, albeit after an initial cold start!

Atlantic College is just one in a number of colleges within the United World Colleges organisation. There are currently 17 different schools and colleges on four continents that teach the International Baccalaureate. The ethos of the UWC is to select students based not on their academic achievement rather, on their personal and aspirational potential.

The leadership team of the Outdoor Activities department made contact with South Wales GeoTours late in 2018 when they became aware of some of my promotional material. The Outdoor Activities department at Atlantic College are responsible for leading students on activities such as rock climbing, caving and kayaking amongst others both on the Heritage Coastline as well as the Brecon Beacons and Gower Peninsula of South Wales. I was contacted to explore if I could provide understanding of the geology of the local coastline to allow staff (with little or no geological background) to communicate the primary geological elements of what their students were climbing on or kayaking past.

The emphasis of the day was to be on the geology at the site of the college itself plus one or two other coastal sites where students go rock climbing. To that end I arranged for them to see the Carboniferous Limestone at Ogmore-by-Sea because they go caving in the limestone caves of the Brecon Beacons, the Lower Jurassic rocks on which Atlantic College is built and where students climb & kayak, and the Triassic rocks at Ogmore-by-Sea and near Barry because they are simply spectacular – to a geologist!

We gathered at Ogmore-by-Sea for an introductory discussion on the basic principles of geology (Fig 1) before introducing the geological history of the Vale of Glamorgan. Throughout the group session I tried to put the rocks and fossils into context with the Plate Tectonic and Continental configuration at the time as they are the fundamental driver on what type of rocks are deposited where. Unfortunately, the weather wasn’t too helpful when I was talking as it was windy and cold and often my presentation material was blowing around.

Fig 1. Introductory talk to the Atlantic College group

The first rocks we looked at were the Early Carboniferous limestones of the High Tor Limestone Formation that were formed between 346-330 million years ago. At that time South Wales was located just south of the Equator and as a result experienced a tropical climate with warm, shallow seas and occasional large reefs forming barrier islands (Fig 2).

Fig 2.Schematic paleo-geography of Wales during the Lower Carboniferous

Limestone is a sedimentary rock that is comprised of crystals of Calcite and Aragonite the differing forms of calcium carbonate. The hot, tropical seas led to high evaporation rates causing the precipitation of calcium carbonate.

A feature of limestone is that it is soluble in the presence of fresh water. As that flowing water runs along natural partings in the limestone it dissolves the fabric of the limestone enlarging the partings to form wide cracks eventually leading to caves. The Limestones exposed at Ogmore-by-Sea are well-bedded but with evidence of Karstic features (Fig 3).

Fig 3. Carboniferous limestone exposed at Ogmore-by-Sea

The limestone exposed at Ogmore-by-Sea has a lot of fossils incorporated within it (Fig 4). We saw many Crinoids (Sea Ferns) that are related to modern day brittle stars & sea urchins plus a number of specimens of a coiled Gastropod (much like modern-day Whelks) and Corals (polyps living within a structure made of calcium carbonate). These organisms were living on and growing up from the seabed or reef surface probably in shallow water and within a diverse and vibrant ecosystem.

Fig 4. Fossil of a coiled Gastropod (Straparollus?) within Carboniferous Limestone

Ogmore-by-Sea is also a great place to see some great exposures of Triassic rocks. Britain during the Triassic Period was situated to the north of the Equator in the interior of the vast supercontinent Pangaea that had previously formed during the late Carboniferous/early Permian Periods (Fig 5). The climate during the Triassic was hot and arid with intense storms and winds leading to the formation of deserts and inland seasonal lakes.

Fig 5. Plate reconstruction during the Permian & Triassic Periods (Britain highlighted in Red)

The Triassic rocks at Ogmore-by-Sea comprise jumbled-up, grey-coloured pebbles and cobbles without any horizontal bedding and are what geologists refer to as conglomerates and breccias (Fig 6). Because the pebbles in a conglomerate are rounded geologist infer that the pebbles have moved a long way from the place where they were eroded as abrasion as the rock fragment flows knocks-off the sharp edges. Whereas a breccia with its sharp-sided rock fragments indicates that it has not travelled very far before being re-deposited.

Fig 6. Triassic Conglomerate exposed at Ogmore-by-Sea containing pebbles of Carboniferous limestone set in a red sandy matrix

The pebbles are formed primarily of eroded fragments of Carboniferous limestone and are set within a red-coloured matrix or cement which is characteristic of the arid Triassic period. The conglomerates and breccias are filling a desert river that has eroded/cut-through the already hard Carboniferous limestones during the Triassic (Fig 7). These desert river systems are known as Wadis in the Middle East today. I have seen countless modern Wadis in Oman and they are always steep-sided and full of a jumble of boulder, pebbles and sand. Most of the time they are dry and only ever have water flowing through them when it rains heavily in the mountains. But when it does rain it does so very hard and leads to water rushing through at great speed and with a lot of power (flash-floods). It is suggested that the Triassic conglomerates and breccias at Ogmore-by-Sea were formed in such a way.

Fig 7. Triassic Wadi (to the right) cutting through Carboniferous limestone (to the left)

We finished our time at Ogmore-by-Sea by moving to the far eastern end of the beach and we saw more Limestone. However, this limestone is different to the Carboniferous limestone in that they are more uniformly bedded and browner in colour (Fig 8).

Fig 8. Early Jurassic Limestones at Ogmore-by-Sea

These rocks have been dated as Early Jurassic in age (circa 199 million years old) implying that there is a time gap of about 130 million years between the two units. They rest with slightly different angle relative to the Carboniferous limestone. Academic geologists have interpreted these Early Jurassic limestones as being shallow sea limestones deposited onto the sides of islands formed of Carboniferous limestone.

You will recall that earlier-on I mentioned about South Wales being located within the supercontinent Pangaea during the Permian and Triassic Periods meaning that almost all rocks deposited during those times were deposited on land. During the latest Triassic and earliest Jurassic Pangaea began to break-up with the separate pieces moving apart from each other to form the continents that ultimately, we are familiar with today. The process of break-up or, “rifting” as geologists’ term it, allowed the seas to start to flood into the former land areas. This is the process that allowed the Early Jurassic limestones that we see at Ogmore-by-Sea to “onlap” onto the islands of Carboniferous limestone.

A really interesting feature of the Early Jurassic limestones is the huge amounts of fossils to be found within them (Fig 9). We found Corals, Crinoids and worm burrows some of which are almost 0.5m in diameter. A fossil collectors dream!

Fig 9. Crinoid stems and coral colonies within Early Jurassic Limestone

All the rocks at Ogmore-by-Sea have been cut by mineral veins. Mostly these mineral veins are coloured white, but some have a pink tinge to them. The crystals shapes vary from plates to much smaller indistinguishable shapes. The majority of the minerals are Calcite, but some are of Baryte which looks very much like Calcite but is heavier. All minerals veins seem to be exploiting (filling-in) fracturs or cracks in the rocks.

After we left Ogmore-by-Sea we drove to Southerndown Bay for a brief look at the spectacular faulting in the high cliffs of Trwyn-y-Witch (Witches Nose in Welsh). Here a large fault has pushed-up older rocks on one side of the fault over younger rocks (Fig 10). The pressures that existed on the fault plane were intense because the rocks immediately adjacent to the fault plane have been squeezed (deformed) into tight folds.

Fig 10. Interpretation of the structure at Trwyn y Witch, Southerndown

It is thought that Trwyn-y-Witch is the result of two different tectonic events. Firstly, during the earliest stages in the formation of Pangaea the Carboniferous limestones were folded and faulted. About 130-140 million years later the Jurassic rocks were deposited on top of the Carboniferous limestone. Sometime after deposition of the Jurassic rocks a second phase of earth movement re-activated the same fault pushing the earliest Jurassic rocks to the right of the fault up over younger Jurassic rocks on the left-hand side of the fault.

Following departure from Southerndown we drove to Atlantic College for lunch. What a beautiful group of buildings form the heart of the college. Effectively it is a castle built in the 13thCentury and known as St. Donats Castle. In the late 19th& earliest 20thcenturies it was owned by the American newspaper publisher Randolph Hearst as a holiday retreat before becoming Atlantic College in 1962.

Straight after lunch we walked down to the foreshore of Atlantic College to take a look at the Early Jurassic Porthkerry formation that is beautifully exposed in the cliffs and the wave cut platform. The Porthkerry formation extends from Southerndown to St. Donats and eastwards to near Rhoose which is a distance of about 12 miles in total. Cliff heights range between 5m to 50m.

A feature of the Porthkerry formation is the regularly alternating limestones and mudstones (deposited in the sea) with individual layers (beds) extending laterally along the coast as far as the eye can see (Fig 11). This means that the geological conditions that produced the rocks was continuous over a large area and in a stable environment. So, what geological process could have caused the repetitive and continuous layering?

Fig 11. Regularly alternating limestone and mudstone beds, of the Porthkerry Formation, St. Donats

The most likely explanation is that deposition of the rocks was controlled by regular alternations in the rising and falling of sea-level. Geologists believe that the primary control on sea-level is the amount of ice at the poles which in turn is controlled by climate. When the climate is cold there is more ice at the poles and sea levels are lower. Conversely, when the climate is warmer there was less ice at the poles and sea-level was higher. Geologists theorise that when the sea-level is lower the limestones were deposited whereas when sea levels rose the mudstones were deposited as the precise location in 3D space was in deeper water.

Other interesting features seen in the cliffs at St. Donats are the clear faults cutting through and offsetting the Porthkerry formation rocks either side of the faults. One small bay is bounded by two faults with the cliff moving downwards between these faults to form what geologists term a “graben.” The entire area of the Vale of Glamorgan is also affected by at least two sets of regional jointing. Jointing forms regular cracks in the rocks with some of the cracks having very small offsets of a centimeter or two to no offset at all. Sometimes the joints become filled with minerals, mainly white calcite. Jointing is likely a late stage flexing of the Earth’s crust as it relaxes after a tectonic period.

One final feature of note is that the formation has abundant fossils. All fossils are marine (sea) animals (recall that during the late Triassic to early Jurassic Pangaea began to rift-apart, allowing the sea to flood over what was desert). Fossils include Ammonites and bi-valve shells (Fig 12) such as Plagiostoma (a clam) and Lingula (a mussel). Plesiosaur and Ichthyosaur bones have been found in the Porthkerry formation, although not by us on the day!

Fig 12. Fossils found at St. Donats: Clams (left) and Ammonites (right)

The final location we visited was a little further east near Barry. At this locality Triassic rocks are exposed but they are very different to the conglomerates and breccias we saw at Ogmore-by-Sea. At Barry the Triassic rocks are very much finer-grained. The rocks are formed of mudstones and fine-grained sandstones and are thought to have been deposited around a lake.

The location is famous for the abundant fossil dinosaur footprints (Fig 13) and tracks seen there. Footprints include the rounded footprints of large plant-eating dinosaurs and smaller 3-toed predatory meat-eating dinosaurs. It is thought that primitive Triassic-aged dinosaurs were living around the lake in a generally arid, desert-like environment and came down to the lake to drink with the small carnivorous dinosaurs hunting the herbivores.

Fig 13. Dinosaur tracks exposed in Triassic rocks, near Barry

We finished the day with the dinosaur tracks at about 3:30pm. The UWC Atlantic College staff were exhilarated if a little tired, after the long day out trying to absorb so much new and often technical concepts & information. The fantastic sunshine also helped everyone enjoy the day and most if not, all left for home knowing more about the geology of their area than they did at the start of the day.

Since the trip I have received feedback from UWC Atlantic College. The leadership team said that everyone really enjoyed the day and that they learned a lot and now have a better appreciation of the landscape when out with their students. Constructive criticism of the day was that some of the group were a little lost at times with some of the geological concepts I introduced and to help them re-enforce the concepts it would be a good idea to provide hand-outs summarizing the key points. This I will prepare for future trips.