Category Archives: geology

Wild words: chalk

21 Wednesday Feb 2018

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Chalk: noun; ‘a white soft earthy limestone (calcium carbonate) formed from the skeletal remains of sea creatures’, according to the Oxford Dictionary, though that seems a relatively simplistic explanation to me. I chose chalk as this week’s word as I was in East Sussex last week and had occasion twice to see the magnificent chalk cliffs known as the Seven Sisters, once at Birling Gap in a howling gale and again, at Cuckmere Haven, on a day that felt like summer had come early to southern England.

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The Discovering Fossils website has this to say about the chalk at the Seven Sisters:

The Chalk at Seven Sisters belongs to the Upper Chalk, and was deposited during the Coniacian and Santonian stages of the Late Cretaceous epoch between 87-84 million years ago (mya). At this time Seven Sisters and much of Great Britain, along with Europe, lay beneath a relatively shallow sea around 40°N of the equator, on an equivalent latitude to the Mediterranean Sea today.

And you can read more about the fascinating process of chalk formation here.

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Fossils from the Jurassic Coast

06 Saturday Jan 2018

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Yesterday a living fossil fungus, today fossicking for fossils on Dorset’s Jurassic Coast – I’m on a roll with the old stuff!

180106 Charmouth fossils (1)

Part of one of my Christmas break days was spent at Charmouth, on England’s south coast, where my friend Sarah and I enjoyed a wonderful long beach walk, much of the time with our eyes down, searching the rocks and pebbles for fossils. Though you’re not allowed to chip away at the cliff face – and you’d be foolish to try, as it can be rather unstable and is subject to frequent mud slips, you are allowed to take fossils from the beach itself.

Sarah spotted one enormous fossil in a big boulder, but that was rather too big to pop in my pocket and bring home.

And, though it took a while to get my eye in, I did eventually find two small pieces of pyrite ammonite and another small rod-shaped rock, which looked very like the belemnite fossils being sold in the local shop. Result!

Glorious mud

23 Thursday Nov 2017

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‘Mud, mud, glorious mud
Nothing quite like it for cooling the blood
So follow me follow, down to the hollow
And there let me wallow in glorious mud.’

171123 mud

I never saw Cardiff Bay before the Barrage was built in the 1990s but, from photos I’ve seen, I believe much of the foreshore was a lot like this, as much of the coastline to the east of Cardiff still is.

The chalk cliffs of the Seven Sisters

23 Tuesday May 2017

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The white cliffs of Dover get all the publicity but, personally, I prefer the magnificent chalk cliffs of the Seven Sisters, near Eastbourne.

170523 Seven Sisters chalk cliffs (1)

It seems unbelievable to me that the chalk is actually the microscopic remains of plankton deposited here as much as 90 million years ago, and that the darker bands, of flint, were probably formed from the remains of sponges during those times when sponges were particularly abundant in the warm seas that once flowed here.

170523 Seven Sisters chalk cliffs (2)

My photos were taken on two visits and from both directions (east to west, west to east), and you can see how different the cliffs look in different weather conditions. They sparkle and glisten in bright sunshine and smoulder like burnished steel on grey days.

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The chalk is soft, erodes constantly and there are frequent large slips (as you can see in the photo below) so, if you’re visiting, stay away from the cliff edge!

170523 Seven Sisters chalk cliffs (4)

Craig-y-Cilau National Nature Reserve

10 Monday Apr 2017

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170410 Craig Y Cilau NNR (4)

Last Wednesday I joined 19 of my fellow Glamorgan Bird Club members on a trip to the Craig-y-Cilau National Nature Reserve. Though our species list for the day totalled around 30, most birds were too distant for photographs but the location, high in the hills on the edge of the Brecon Beacons National Park, is stunning!

The limestone cliffs here were once quarried and our path – at times rather narrow and with a steep drop to one side – followed the route of the old tramway, the signs of which could still be seen in the stones. The cliffs are riddled with caves, with a mapped system of over 400 miles of passageways, though you’d be foolhardy to enter without an experienced guide.

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Though the birds were somewhat elusive, we were surrounded by flourishing and sometimes rare flora, with wildflowers aplenty and some interesting fungi.

And the panoramic views, towards the towns of Crickhowell and Llangattock and over the surrounding countryside, were simply sensational. We didn’t get a chance to explore the whitebeam-filled woodlands or the unique raised bog so I’m already planning a return trip.

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Wales walks: Penarth to Lavernock

01 Saturday Apr 2017

Posted by in geology, insects, lichen, nature, seaside, walks, wildflowers

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Since moving to the seaside two months ago I have been thoroughly enjoying exploring my new surroundings and a particular favourite has been the walk from Penarth to Lavernock, a very small 1.5km section of the Wales Coastal Path.

170401 Coastal Path flora

Despite its short length, it can take me rather a long time to walk because the path is bordered with all manner of trees, shrubs and wildflowers, so my eye is constantly drawn to checking these out.

I am fast discovering that the abundance of flora supports a wonderful array of fauna: flies and bees are flocking to the freshly opened flowers of Alexanders (Smyrnium olusatrum), recently arrived migrant Chiffchaffs (Phylloscopus collybita) are announcing their arrival with their familiar onomatopoeic song while recharging their batteries on flying insects, and various species of terrestrial snails sleep, slide and slither amongst the leaves.

There’s also a huge diversity of lichens, presumably much encouraged by the Welsh rains, the occasional wild winds, and the clean and salty seaside air.

170401 Coastal Path geology

Here and there gaps in the trees and shrubs reveal tantalising glimpses of the fascinating geology this coast is famous for (I have yet to venture down the cliffs but that will soon happen).

170401 Coastal path Flatholm

Boats and ships chug up and down the Bristol Channel; planes from Cardiff airport fly off overhead to foreign shores; the lighthouse on Flatholm beckons; and views of Penarth’s iconic pier abound.

170401 Coastal Path

But most of all I love the places – and there are many – where the foliage closes in overhead, to create little tunnels of vegetation. I find there’s something magical about such spaces, a little like stepping through the wardrobe door to emerge in a real-life Narnia.

‘The everlasting charm of fossils’

29 Wednesday Mar 2017

Posted by in geology, molluscs, nature

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I’ve always been fascinated by fossils and would love to find a little something special (I’m hoping my move to the south Wales coast will help fulfil this dream as there are fossils, and even dinosaur bones, in nearby cliffs) so imagine my delight when we visited a fossil exhibition, museum, factory and shop during a tour of Morocco back in 2014.

We were near the town of Erfoud, in southern Morocco, an area which is now extremely arid but 500 million years ago was under the ocean. Some of the creatures that inhabited that ocean – in particular, the cephalopod molluscs and trilobite anthropods – became stranded in muddy lagoons that gradually dried out and, over time, the mud and creatures were transformed into a fine-grained calcareous rock containing the perfectly preserved fossilised creatures.

The museum-come-shop had some wonderful specimens on display and for sale, including large items like tables and lamp bases, wash basins and fountains. I couldn’t quite fit a table-top in my backpack but I did buy a couple of small trinkets, shown in the last photo included here. And if I do manage to find anything more local, I’ll definitely be posting about it!

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Another pinch of salt

22 Wednesday Mar 2017

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170322 Salineras de Maras (9)

Last week I showed you the largest salt flats in the world in Bolivia. This week we’re still in South America but have moved north to Peru, to Salineras de Maras in the Andean Mountains about 40 kilometres from Cusco, where salt has been mined for hundreds of years.

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The earliest salt pans are thought to have been constructed by the Wari civilisation, but it was their successors, the Incas, who recognised the commercial opportunities of salt-mining and increased the extent of the pans, which now cover much of a steep gorge that runs down in to the Sacred Valley. The salty water bubbles to the surface in a small spring from ancient salt lakes now buried deep below the earth’s surface, and is ingeniously conveyed down the mountainside via a meandering maze of irrigation channels. People from the local community work constantly to maintain these channels and to ensure just the right amount of water is allowed into each pan before the pan is closed off and allowed to dry out. The sun’s heat evaporates the water, leaving behind a thick coating of salt, which is harvested for sale – and then the whole process starts all over again.

Salineras de Maras is very near the intriguing Inca site of Moray and the wonderful market town of Chincero, so combining a visit to all three makes for a thoroughly enjoyable and interesting day’s excursion from Cusco. Or, if you want to spend a little more time getting a feel for your surroundings, try the hike from Moray through Maras and the salt pans down to the Sacred Valley. It’s well worth the effort.