Heart of the Park and Waterfall Country Tour on 23rd August 2016

Today we had excellent weather in the Brecon Beacons National Park, and I took a family of four on the Heart of the Park and Waterfall Country tour.

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A view of the Beacons near Brecon just before the start of the tour.

DSC_3760Our first stop was Mynydd Illtud  with spectacular views over all four mountain ranges in the National Park, a Roman road, and iron age fort, glacial moraine, and scientifically important wetland.DSC_3763DSC_3766DSC_3769We then journeyed on past the Crai reservoir with wonderful views on the Black Mountain to the Upper Swansea Valley.DSC_3772DSC_3775We then visited the Allt Rhongyr Nature Reserve and Penwyllt for dramatic views of the Upper Swansea Valley.DSC_3776DSC_3777DSC_3778Next we went to Henrhyd waterfall which was gushing with water from all the recent rain. This is the highest waterfall in South Wales and flows over the famous ‘Farewell Rock’ the bottom layer of the South Wales Coalfield. When early geologists first described it fossil tree trunks were found at its base. This fall has also featured in the Batman films

DSC_3781DSC_3783DSC_3785It was the on to Bwa Maen. Bwa Maen Fold – The ‘Stone Bow’ this is a spectacular fold in the Carboniferous limestone.

DSC_3787Sychryd Falls/ Sgydau Sychryd –  This is a cascade of water that flows between Dinas Rock and Bwa Maen.

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Sgwd Isaf Clun-gwyn

The ‘lower fall of the white meadow’ is the middle of three falls.

DSC_3790DSC_3792Clun Gwyn Waterfall / Sgwd Clun Gwyn –  The ‘fall of the white meadow’ is the uppermost of the three celebrated falls on the Mellte. It is formed where a north-northwest to south-southeast trending fault brings hard sandstone up against softer mudstone.

DSC_3793DSC_3795DSC_3807Then we walked on to Sgwd yr Eira. Famous for being the falls behind which you can walk, the ‘falls of snow’ plunge over a hard band of sandstone whose overhang protects the walker from the full force of the water.

DSC_3816DSC_3819DSC_3822Then we visited Porth Ogrof – The largest cave opening in Wales.DSC_3824DSC_3826The day finished with a visit to Craig Cerrig-gleisiad and Fan Frynych National Nature Reserve –  Craig Cerrig-gleisiad means ‘cliff of the salmon(-coloured) rocks’ and is a cwm (cirque) formed by a glacier which deposited moraine and created a sheltered environment where rare Arctic and Alpine plants live.

All together it was a mammoth yet excellent day in wonderful weather. I you feel like joining the tour yourself please join me here

http://breconbeaconstours.com/heart-of-the-park-and-waterfall-country.php.

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Field Trip to the Glamorgan Heritage Coast

Scenery Explained Wales to Hay-on-Wye U3A on a field trip to the Glamorgan Heritage Coast. First we visited Southerndown then Nash Point then Llantwit Major.

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James Cresswell on a tight fold caused by movement on the nearby fault
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Wave cut platform Nash Point. Blue Lias Jurassic sediments
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Nash Point
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Valley calved out by glacial melt water at Nash Point

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100 ma unconformity 300 ma Carboniferous limestone at base overlain by 200 ma Jurassic sediments
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100 ma unconformity 300 ma Carboniferous limestone at base overlain by 200 ma Jurassic sediments

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Folding and Faulting

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An ammonite in blue lias Jurassic limestone
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Fossil wood in shallow water Jurassic sediments

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Gryphea

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Four new tours in the Brecon Beacons

We have revamped out Brecon Beacons sightseeing tours for the spring of 2016. We are now offer four new and improved tours www.breconbeaconstours.com

Tours with names

Brecon Beacons Tours

Scenic, historic, natural and cultural tours available daily, and starting either at Abergavenny train station, the public transport gateway to the National Park, or at your accommodation within the National Park.

Use the train and do our tours as a day trip from UK cities e.g.: Cardiff, LONDON, Bristol, Birmingham or Manchester

Approximate journey times to Abergavenny station: Cardiff – 45 mins, Bristol – 1 hr 5 mins, LONDON – 2 hrs 15 mins,
Birmingham 2 hrs 20 mins, Manchester – 2hrs 45 mins

The Brecon Beacons National Park is simply too big to see all the major sites in one day. I therefore offer 4 different tours that focus on 4 different areas of the National Park.

 

Fforest Fawr part 8

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Structure

The dominant structural features in the Geopark are three parallel faults that run through the park from the south west towards the north east. These are named the Carreg Cennen Fault, the Swansea Valley Disturbance and the Neath Disturbance. These faults may well represent ancient lines of weakness from when the landmass of England and Wales was coming together as a series of terranes in the Precambrian. They were active in the Caledonian Orogeny and then again in the later Variscan Orogeny, a mountain building event in the mid to late Carboniferous caused by Laurussia and Gondwana colliding to form the supercontinent Pangaea. Even today as Africa crashes into the Europe to form the Alps it is possible to have small tremors along this fault. In 1999 there was an earthquake measuring 3.5 on the Richter scale centred on Sennybridge. The Variscan Orogeny also had the effect of folding the pre-existing sediments. The best place to see the structural geology of the geopark is Bwa Maen near Pontneddfechan. Here the Neath Valley Disturbance can be seen adjacent to a fold in the Carboniferous Limestone, the two structures together form a faulted anticline (see fig. 7).

Fforest Fawr part 7

waterfall

Overlying the Carboniferous limestone are three formations of rock that make up the Marros Group. The lower layer of this is the Twrch Sandstone. This is a quartzite and in places is 98% silica. This silica was mined at Pontneddfechan near to the current Waterfall Centre, which functions as the Geopark Visitor Centre, and then crushed to make fire bricks. These bricks were commonly known as Dinas Fire Bricks and were used to line furnaces. They were sold all over the world and even today in Russia fire bricks are still known as Dinas Bricks. Overlying the Twrch Sandstone are the Bishopstone Mudstone and Telpyn Sandstone formations. These alternating layers of mudstone and sandstone form faulted block over which the many waterfalls of ‘Waterfall Country’ flow. These waterfalls on the Mellte and  Hepste rivers near Pontneddfechan form arguably the finest collection of waterfalls in Britain.

Overlying the Marros Group but only jutting into the Geopark on its extreme southern fringe are the South Wales Coal Measures. These coal measures are responsible for the industrialisation and urbanisation of South Wales, to the south of the Brecon Beacons National park and Fforest Fawr Geopark. The lower most part of the Coal Measures is the ‘Farewell Rock’. This was named first by early iron miners who found no more iron nodules below this rock and the name was later adopted by the coal miners who also found no coal beneath this layer. The ‘Farewell Rock’ is beautifully exposed at the Henrhyd Waterfall (fig 6). This waterfall near Coelbren is the highest in South Wales. It is possible with care to walk behind the waterfall and it is the Farewell Rock that forms the hard cap over which the water flows. In the 1830’s Sir William Edmond Logan, after whom Canada’s highest mountain is named, was mapping the South Wales Coalfield, and discovered two fossilised tree trunks in the gorge below the waterfall. These fossils now stand outside Swansea Museum. Another place to see the Farewell Rock is in Pontneddfechan at the start of the waterfall walk behind the Angel pub. Also near to Pontneddfechan is the Cwm Gwrelych Geo Heritage trail. This trail, equipped with audio information points takes you on a guided walked through coal measures in a previously industrialised valley. Henllys Vale near Brynaman is also another good place to see the coal measures exposed . The Geopark has produced a Geotrail for this location. But if you really want to see coal, the best place has to be the National Coal Museum which is part of the Blaenavon World Heritage Site. This is actually outside the Geopark being near to the eastern boundary of the National Park. Here it is possible to descend the Big Pit mine-shaft and also visit a replica mine. It is also possible to visit the ironworks where my great great grandfather Edward Pritchard Martin was the General Manager.

Fforest Fawr part 6

Porth yr Ogof

Carboniferous

As the sedimentary basin continued to fill and subside the land eventually fell below sea level once gain and in the early Carboniferous a shallow tropical sea rather like the modern day Bahamas formed over the Geopark region. This has deposited a band of Carboniferous Limestone stretching along the southern margins of the Geopark from Carreg Cennen Castle in the west to Merthyr Tydfil in the east (see fig. 1). In places these rocks contain fossils of the creatures that lived in the  tropical sea such as corals and crinoids (fig 5). A great place to see these fossils is on the geology trail which leads from Craig-y-nos Country Park to the summit of Cribarth Mountain. This mountain and nearby Penwyllt are also an excellent place to see industrial archaeology. The limestone was quarried here and burnt in lime kilns to provide quick lime for agriculture and the iron industry.

The limestones also host Britain’s deepest cave. Ogof Fynnon Ddu is 308 metres deep and boasts 50 km of passageway. The cave is situated under Penwyllt. This cave is for experienced cavers only, but can be explored by becoming a member of the South Wales Caving Club. A more accessible cave is the nearby Dan-yr-ogof  cave. This cave is part of the National Show caves Centre of Wales, and has extensive walk ways where it is possible to see amazing stalactites and stalagmites. Another notable cave in the Geopark is  Porth yr Ogof near to Ystradfellte. It has the largest cave opening in Wales which is 17 m wide and 5 m tall.

#Welshflag at #McMurdo #DryValleys #Antarctica

Dear Scenery Explained Wales followers, I am still in Antarctica but will be back home in Wales in 2 weeks. After our successful landing at Cape Royds and outing of the Welsh Flag we journeyed on to the McMurdo Dry Valleys, the driest place on earth, where I once again brought out my Welsh flag. Below is a description of our day:

Today started early, really early. In fact it had already gone midnight by the time we went to bed after our successful landing at Cape Royds on Ross Island for our visit to Shackleton’s hut. However at quarter to 4 it was time to get up again for a pre-breakfast excursion to Scott’s hut at Cape Evans, further down the coast on Ross Island. The swell was quiet large and the wind was almost 40 knots, but we felt we could do it. We started to launch boats, but the ship was drifting and unable to hold its position due to the wind, so unfortunately we had to call off the operative.

We then recovered the only lowered boat and fell asleep again, as the ship sailed back across McMurdo Sound to the entrance of the Dry Valleys. Unfortunately the sea ice situation had deteriorated further and we were only able to get within in 6 miles of the entrance to the valleys. The wind was still blowing 40 knots and the Trans-Antarctic Mountains were still draped in cloud. It was all very depressing and looking very doubtful.

We waited and waited, then the cloud showed signs that it was lifting, however the wind was still 40 knots. Expedition Leader Don, and chief helicopter pilot Marcello decided they would do an exploratory flight into the Dry Valleys to see what the wind conditions were like up there. The pilot very skilfully lifted off the ship in the windy conditions and headed out across the ice towards the lifting cloud of the Dry Valleys.

After 45 minutes they returned. We were all eating in the dining room and Don announced that it was a GO! The wind was still high at the ship, but inside the valleys there was no wind and it was do-able.

As the ship’s Geologist, I was lucky enough to be selected to fly in on the first helicopter to prepare the landing site for the passengers. It was an experience I will never forget. First we flew over ice floes and newly forming sea ice, with sleeping seals near to the shore line. Then we flew up over the land – dry land with no snow even though we were at nearly 78 degrees south. As we flew over the bare ground, I could see frost wedges caused by freezing and thawing of the permafrost. Then we saw the first glaciers: the Wales glacier coming in from the left and later the amazing piedmont of the Commonwealth glacier and our destination the Canada Glacier, coming in from the right.

The Dry Valleys are free of ice because the Tran-Antarctic Mountains are so high. Ice from the East Antarctic Ice Sheet does not spill over into them to flow down these valleys. In addition to this the area is incredibly dry. There is very little snowfall and this snow cannot accumulate as a glacier. Any snow that does occur, often sublimes straight to water vapour or is blown out by the extreme catabatic winds that can rage down the valleys. As chance would have it there was some snow there on our visit day. The previous day’s storm had left a thin layer on the higher ground and on some of the boulders but it was quickly ablating away.

The helicopters landed at the foot of the Canada glacier, with forms an elephant’s foot or piedmont glacier as it emerges from it restrictive Canada Valley into the main dry Taylor Valley. In front of the glacier were a few ice blocks produced by an extremely low rate of calving. In the hottest days of the year these will melt and flow into nearby Lake Fryxell, which today was completely frozen. The interior of this lake is always frozen but on the hottest days of the year a thin moat of water will form around its edges.

On the valley floor, at our landing site, there were three mummified seals. These unfortunate beasts had once made the wrong call, and crawled the wrong direction to find the sea. Eventually they died, but because the conditions were so cold they have been perfectly preserved. One of these seals has been dated at 2000 years old. Also on the valley floor was a large assortment of different rocks types, but all were either igneous or metamorphic. These rocks show that the Taylor Glacier has at some stage flowed down through this valley because these are all the rocks types that outcrop higher up in the Taylor Valley.

As the day went on helicopters and groups of passengers came and went. Eventually the last passengers had arrived and then it was time to go on another incredible helicopter ride over the glaciers, and the sea ice back to the ship. Visiting the Dry Valleys was a dream come true for me, and today was my best ever day working as a guide on an expedition ship.

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#Welsh boys at #Erebus #Antarctica

I am away from Wales for a few weeks guiding on a trip in Antarctica. Here I was a few days ago at Cape Royds on Ross Island under the towering bulk of Mount Erebus. Mount Erebus is one of only 3 volcanoes in the world that has a permanent lava lake. It is is also the world’s southern most historically active volcano. Cape Royds is also the site of Shackleton’s historic hut which was used for the Nimrod Expedition where he got within 95 miles of the South Pole.

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Fforest Fawr part 5

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Devonian

The Caledonian Orogeny the name given to the mountain building event that produced the Caledonian Mountains lasted on into the Mid Devonian. The Caledonian Mountains were a huge chain of mountains that were probably Himalayan in height and  stretched from what is now Svalbard down the coasts of East Greenland and Western Norway, through the British Isles on to the Appalachians in North America. Whenever a great chain of mountains is thrust up, it will be eroded down and huge thicknesses of sediment can be deposited in sedimentary basins adjacent to the mountain ranges. The Devonian scene in the Fforest Fawr Geopark would have been something like modern day Pakistan, with a huge mountain chain to the north and an arid plain to the south over which rivers periodically flooded depositing sediment.

Devonian rocks cover more of the Geopark than rocks of any other age, and all the high peaks in the Geopark, the Black Mountain, Fforest Fawr, and the Brecon Beacons (Fig. 2) are made from Devonian Old Red Sandstone. Many of the rocks are red in colour as the name would suggest.  This is due to haematite that formed in these arid conditions. In other places the rocks are green and this is due to a different oxidation state of the iron that may be due to water percolating through the sandstone t a later date. In many places in the Geopark, such as on the slopes of Bannau Sir Gaer on the Black Mountain sedimentary structures such as cross bedding are clearly visible. At a few rare sites such as Heol Senni Quarry fossil fish have also been found. The Devonian is also known for the remains of the planets first forest and in certain places such as near the summit of the Black Mountain, black organic material can be found within the sandstone (Fig 3).

Rocks of the lower Devonian are preserved as the St Maughans, Brownstones and Senni formations. These are all sandstones and mudstone. The middle Devonian however is missing, presumably there was a period of erosion after they were deposited removing them before the Upper Devonian Plateau Beds and Grey Grits were lain down. The Plateau Beds are so called because they cap many of the highest peaks in the Geopark. Figure 4 shows the Plateau Beds lying unconformably on the Brownstones.

The best places to see Devonian rocks in the Geopark are the walks that climb the high mountain peaks. Pen-y-Fan at 886 metres is the highest mountain in southern Britain and the views from the top are magnificent. However it is also a very popular mountain and at certain times of the year can be quiet busy. A wilder and more isolated experience can be had in the west on the peaks of the Black Mountain.