Category Archives: Geological Site

Seljalandsfoss

I know it’s been over a month since I came home from the the land of fire and ice, but here are a few more pictures from the wonderful land of Iceland.  In this case it of the waterfalls around the area of Seljalandsfoss.  This particularly wonderful foss is on the main round south-east before you get to Vik.  It drops about 60m from the volcanic cliffs above and has calved out a plunge pool and has a fantastic undercut rock shelter that allows visitors to walk behind the falls (though I would say to watch your step as the patch can be wet and slippery – and when the weather is as windy as it was on our trip the spray will soak you).

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DSCN2634DSCN2623DSCN2639About 500m along the cliffs to the northwest of Seljalandsfoss is the hidden waterfall Gljúfrafoss.  This is worth having a look at, though your feet will get wet as you have to walk along the stream to get into the cave.  With Gljúfrafoss you have a waterfall that has cut back into the cliffs and you have to do a bit of exploring to see this beautiful foss.

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Fenn’s, Whixall & Bettisfield Mosses

On a cold but sunny winters day I made what is my second visit this area.  The picture above is from a previous trip when the weather was a lot warmer.  It was still freezing on my visit the other day, despite it being in the middle of the day.
DSCN0641Location & Access: The Fenn’s, Whixall & Bettisfield Mosses straddles the English-Welsh border about 5 miles south-west of Whitchurch.  There is no major road to the site, so you’ll have to take one of the narrower country lanes off the A495, B5476 or B5063.  If you fancy taking a boat though the Llangollen Canal runs through the middle of the site.  The site is relatively flat and shouldn’t provide any problems, though the walk from one of the carparks can be a bit of a trek if you have mobility problems.

Geology: The geology of the area is perhaps less obvious than the hills & valleys I normally write about.  The Mosses are a rare environment, being a lowland raised bog and small areas of wetland it is a unique habitat for wildlife too.  Their formation began about 12,000 years ago as the ice sheets retreated north.  In amongst the till were depressions filled with water and melting ice.  These formed the kettle holes that dominated the north Shropshire, south Cheshire and Wrexham area.  Some of the these holes remained full of water and form the numerous kettle ponds that can be found in the area.  Good examples can be found in Ellesmere and Delamere.  In the case of the Mosses the hole filled up with layer upon layer of peat.  This has created an acidic peat bog that has made a fantastic, albeit soggy under foot, environment and a link to our country’s icy past.

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Wildlife: Besides the peat bog and its like to an ancient glacial past the Mosses is a great place for wildlife…well when its not frozen over ;).

Alongside the myriad of insects and spiders there are also adders and a wide range of birds, and according to one local I spoke to, the rarely sited water shrew.  Unfortunately due to it being winter I didn’t see most of these.  I did manage to get some pictures of the water fowl in the area.

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These are my first attempts at photographing flocks of birds in flight.  I had mixed results with many of pictures focusing on the background rather than the birds, but I don’t think they’re too bad for a first timer.  The ducks that I’ve managed to get shots of include Shovelers (Anas clypeata), Wigeons (Anas penelope), Teals (Anas crecca) and Mallards (Anas platyrhynchos).  I also saw some Pintails (Anas acuta) and Lapwings (Vanellus vanellus) but happened to be changing the battery at the time.

References: Fundamentals of the Physical Environment (3rd Edition) by P. Smithson, K. Addison & K. Atkinson (2002).  Geology (2nd Edition)by S. Chernicoff (1999).  Geology of Shropshire (2nd Edition) by P. Toghill (2006).  The Geology of Britain – An Introduction by P. Toghill (2006).   iGeology map from the BGS (2015).  Information leaflet from the site and produced by Natural England and Cyngor Cefn Gwlad Cymru (Countryside Council for Wales).

 

Lilleshall Mount

About halfway between Telford and Newport, along the A518 is the lovely little village of Lilleshall.  Watching over it is the Lilleshall Hill.  At 132m high above the flat farmland it’s pretty hard to notice,  especially with a 21m high monument sitting on top of it.

Location & Access: The Hill is just to the east of the A518 and can be accessed via a small tract just off a road called Hillside East which comes off just opposite the church.  There isn’t a lot f space to park in the village so you may have to pull in to the side of the road just outside.  At just over 100m above the plain it’s hardy a struggle to climb up, though the path can be a little muddy after it has rained.  The path slopes gently and so should prove too much of a problem.

Geology: Lilleshall Hill represents the northern most exposure of the Uriconian Volcanic group and is itself made up of a mixture of rhyolite, andesite, basalt and tuff.  This would make the formation about 542-635 million years old.

DSCN0432There are a few decent exposures for anyone who wants a sample, and being the short then its relatives the Wrekin and Caradoc it takes a little less effort for those who don’t want to climb for too long.

For a modest sized hill you can get a decent view of the Wrekin to the south-west as well as the sandstone ridges that rise out of the North Shropshire and South Cheshire plains.

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Other Stuff: The Monument is dedicated to the first Duke of Sutherland and is pretty impressive.

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Dedicated to George Granville Leveson-Gower, the 1st Duke of Sutherland, it looks to be made of local sandstone.  I rather enjoy the inscription and how he is described as “the most just and generous of landlords”.  I’d like to hear what his tenants really thought of him, though I shall be very unscientific and read between the lines of the “he went down to his grave with the blessing of his tenants” as perhaps giving a hint of that.  For those who maybe unaware, this Duke of Sutherland was one of the richest men of his era and he was in part responsible for the Highland Clearances that were taking place in Scotland at the time…a fantastic example of the needs of the rich capitalist overriding those of the poor labourer…sorry went on a ‘high horse’ moment there.  But seriously if you’re unaware of the main cause for the Scottish Highlands being one of the least populated parts of Europe then I suggest you read up on it.

Anyway back to happier things.  The light scrub land around the hill, coupled with the farmers’ fields in the area makes it a good place to see wildlife (in particular birds).  Sparrowhawks, buzzards, wrens, finches and woodpeckers are common sights.

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Reference: The Geology of Britain; An Introduction by Peter Toghill (2006),  iGeology map from the BGS (2014) and the notice board from the site, Wikipedia for the Duke of Sutherland.

 

Wenlock Edge

The Wenlock Edge is a limestone escarpment that runs about 31km (19 miles) through the countryside of Shropshire.  At its northern point is the village of Much Wenlock and at the south Craven Arms.

Location & Access: Being such a long feature it isn’t that hard to miss on a map of Shropshire, basically look south of Telford and you should find it easily enough.  The road B4371 runs along the top of most of the Edge.  There are several car parks along the Edge as well as many paths to walk, so there are lots o places to visit depending upon your ability ad how long you want to be up there.  For me I like to pull in at a car park just north-east of the village of Presthope.  There is a nice walk along the top of a quarry.

Geology: The Wenlock Edge is made up of limestone and lime-muds from the Silurian Period (about 423-426ma).  The area used to be a reef and fossils are abundant along this walk.

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The fossils you can find there are mostly corals, crinoids and shell fragments.

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Above are some pictures of some of the fossils that can be found; mostly corals and fragments of shell.  It’s one of the best places in the county to go fossil hunting.  Pretty much every rock you pick up will contain something of interest.  Fossil collecting is allowed at the Edge, just try not to do too much damage as you do so and remember to leave something for those who will follow.

Along with fossils you can find places where you can see the results of sedimentation, bedding plains and folds (albeit in miniature).

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Other Stuff: Along with geology the Edge is a good place to enjoy the English countryside.  The area is a composite of mixed woodland and farmers fields full of livestock.

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It’s also a place of a lot of woodland wildlife.  Some of the birds that you’ll see include Blue, Great and Marsh Tits, all sorts of finches, Greater Spotter Woodpeckers, Nuthatches, Common Buzzards and I’ve even seen Red Kites on rare occasions.

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Reference: The Geology of Britain; An Introduction by Peter Toghill (2006),  Sedimentary Petrology (3rd Edition) by Maurice E. Tucker (2001), iGeology map from the BGS (2014) and the notice board from the site.

Hulme Quarry

For today’s geological site, I’ve gone beyond the boundaries of my native Shropshire to neighbouring Staffordshire.

Location & Access: Hulme Quarry is located to the east of Stoke-on-Trent, about 1km north-east of Longton at 52*59’49” N, 2*06’28” W.  The whole area is a country park (Parkhall Country Park), nature reserve and a designated SSSI.  The site can be reached from either the A520 (Weston Road) or the A5272 (Park Hall Road).  There are plenty of carparks at the site and most of the paths are wide and well maintained.  There are a few inclines, but nothing too steep (depending upon the path).  There are multiple paths so that someone with mobility issues should still be able to enjoy the place.

Geology: The whole quarry is dominated by the Hawksmoor Formation 246-251Ma which puts it at the very early Triassic Period.  The whole quarry is a collection of red sandstone and conglomerate, and is an excellent place to see this formation.  The quarry sides are easily observable and accessible (though be careful of falling rocks).

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The conglomerate and sandstone can be seen on top of each other in bedding layers.  In the sandstone you can see the cross bedding from the movement of the ancient sand dunes.  There are small layers of pebbles in the sandstone suggesting periodic water movement over the sand dunes.  The conglomerates are the result of a river that moves over the area, and was probably ephemeral.  This is evidenced by the presence of regular graded bedding amongst the pebbles, suggesting regular changes in the flow of the water.  The pebbles themselves are made up mostly of well rounded quartz.

iphone pics 09_14 720The red colour of the rock comes from the presence of iron oxides, left behind by evaporating water.  The combination of red colour, cross bedding sand dunes and ephemeral streams shows that this place was once a desert.  This is typical of rocks from the Permian and Triassic that can be found around Britain.  Occasionally you might find a small patch of mudstone.  I remember being shown some when I visited this site at university several years ago, though I couldn’t find it again this time.

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Other Stuff: The whole area is a beautiful place to walk around.  There are numerous paths, plenty of places to walk, pine tree forests and areas of lowland heath & brush.  There’s bird watching for those that are into that sort of thing, plus plenty of places to ride a bike.  On a hot summers day, with the brush and the red sand, it’s easy to imagine the areas desert past.

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Reference: The Geology of Britain; An Introduction by Peter Toghill (2006), Geology (2nd Edition) by Stanley Chernicoff (1999), Sedimentary Petrology (3rd Edition) by Maurice E. Tucker (2001), iGeology map from the BGS (2014) and the notice board from the site.

 

Ingleborough Cave

Time for my second post of my Yorkshire Dales trip.  As I alluded to in my last post about Malham Cove, one of our goals for the trip was to visit Gaping Gill.  Sadly this wasn’t open due to a technical fault, so instead we visited the nearby Ingleborough Cave.  One thing to note is that this isn’t a potholer’s cave, it’s a show cave.  My own potholing experience amounts to a trip down an abandoned slate mine in Wales…anything more adventurous and I’m likely to become a troglodyte.  Oh and apologizes for the quality of some of the images, it’s a little hard to take photos in the dark cave light.

Location & Access: To get to the cave, park in the village of Clapham, just off the A65.  The cave is about 2km north of the village located around 54*08’05” North, 2*22’38” West.  To get to the cave you follow the path north out of the village.  The path is wide and in very good condition (rather bizarrely a toll path too so bring some pennies), so you shouldn’t have to much trouble walking to the cave.  Sadly there is no closer public vehicular access, so you’ll have to walk.  Being a show cave, Ingleborough Cave is geared towards families, the access is good and the cave floor has been given a layer of concrete to allow disabled usage.  This doesn’t spoil the aesthetic to much.  The tour of the cave does involve a guide and will cost money some bring some cash.

Geology:  The cave is in the bedding planes of the Garsdale Limestone Formation (331-339Ma) and like Malham Cove it was once a shallow, carbonate sea.  In some places you can actually see the fossils of the coral and other organisms.

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The cave was carved out by river water and was partially filled in by glacial till, some of which has been removed to open up the cave.  Not all of it has been and the full extent of the cave is not yet know.

IMG_2206Excavations are still on going and have brought up the remains of a woolly rhinoceros tooth, from the Devensian Glaciation (about 10,000 years ago).

There are several underwater pools still in the cave, and the cave itself is regularly flooded when there are heavy thunderstorms.  When the cave was first explored in 1837 it was flooded, the water held back by a calcite dam.  This was blasted to drain the lake at the time, but parts of another calcite dam can be seen.

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The historic level of the cave water is marked out at a level where you find the cave coral deposits below the waterline and the flowstone above.

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There are plenty of stalactites and stalagmites in the cave of various sizes, the biggest of which is The Sword of Damocles and is a few metres long.

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Along with these you will see plenty of helictites and speleogens as well as other cave formations.  A look at the feature image to this post shows how the natural cleavage & faults in the rock are exploited by the water and form the basis of the stalactites.

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Overall this a good cave to visit, especially if you are not an experienced caver, and a good alternative to Gaping Gill if the winch is broken.  It’s a show-cave, but a good one.  There are plenty of formations to see, and if you are in the area I would recommend visiting the cave if you have a spare couple of hours.  They also have a good website explaining the cave and showing more pictures at www.ingleboroughcave.co.uk.

Reference: The Geology of Britain; An Introduction by Peter Toghill (2006), Geology (2nd Edition) by Stanley Chernicoff (1999), http://www.ingleboroughcave.co.uk and the tour guide on the day.

Malham Cove

This week I have had the opportunity to visit the fantastic Yorkshire Dales in the north of England.  I got a chance to visit a few sites.  Much to our disappointment we weren’t able to get down Gaping Gill due to a technical fault with the winch, so we instead saw a few other places and I’d thought I’d share them with you.  The first is epic Malham Cove.

Location & Access:  Malham Cove is located in the south half of the Yorkshire Dales National Park at approximately 54*21’41” North, 2*09’28” West, about 1km from Malham village.  You can park a car in the village (itself a wonderful place to see) and walk up the road to the cove.  The road is good and there is a slight incline.  just above the village is a clearly marked, good quality path to the cove…and to be honest you really can’t miss it from there.  People with mobility issues shouldn’t have much trouble walking along the path, though the road can be a bit of a trek.  Warning!  The main path goes through a field of cows so beware of bovines.

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Geology:  The underlying rock is Carboniferous Limestone from the Garsdale and Danny Bridge Formations (331-339Ma), and represents a depositional environment of a shallow carbonate sea, full of corals and shell creatures.  That was then, what about now?  Like much of northern England the current landscape is largely the result of the various glaciations of the past, in particular the Devensian glaciation which ended about 10,000 years ago.  Malham Cove is thought to have been formed slightly earlier (about 12,000 years ago) as the ice retreated north.  The melting glaciers produced a large amount of run-off, and with the ground still being semi-frozen permafrost the water eroded the limestone instead of infiltrating into and dissolving it as happens now.

This led to the wonderful dry water seen today.  The semi-circular Malham Cove is about 80m high and about 300m across.  This makes it higher, but only about half as wide as the horse-shoe at Niagara Falls.  This gives you an idea of what the falls would have looked like in full flow 12,000 years ago.

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IMG_2331You can see the bedding planes in the limestone and if you look at the right of the image above you should be able to see two climbers ascending the cliff face (right of the centre tree, about half way up the picture in yellow).  This gives you an idea of the scale of the place.  At the base of the cliff is a small stream, exiting from one of the many underground river systems in the Dales.

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Although you should always be careful approaching a cliff face I would recommend getting as near to the base as possible and looking up…it’s fantastic.  I tried to take a few pictures, but none of them do it justice, so you’ll just have to go there yourself.  Stand in the centre of the horse-shoe, close to the base and look up, it’s this wonderful bowl shape.

Above the falls is another wonder of the Dales; the limestone pavement.

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These are a special feature, common to the Dales, but rare in the rest of the UK.  The flat surface is a bedding plane in the limestone, exposed by glacial & periglacial erosion.  This produces the flat ‘paving slabs’ called clints.  The gaps in between are the result of rain water getting into cracks in the limestone and dissolving some of it.  These gaps are called grykes.  Walking along a limestone pavement is quite an experience, but be warned some of the clints are wobbly and the grykes can be wide and deep.  Some of them may even be filled in with a thin layer of soil & grass so watch your step.

Other Stuff: You’ve got glacial valleys & erosion, caves, underwater rivers & springs, a dry waterfall higher than Niagara and limestone pavements…what more could you want? OK well aside from the geology it is also a great pace to catch a glimpse of one of my favourite birds; the Peregrine Falcon.  These nest up on the cliff face your chances of seeing one is good.

To sum up, if you are ever in the north of England Malham Cove is worth the visit.  The pictures I’ve posted really don’t do it justice, you’ll have to go see it for yourself.  Stay geogeeky as I’ve got more from the Dales that I’ll post soon.  Enjoy.

Reference: The Geology of Britain; An Introduction by Peter Toghill (2006), Geology (2nd Edition) by Stanley Chernicoff (1999).

 

 

Geological Time Part 2 – The Periods in Shropshire

As part of my geological time series I thought I’d have a look at where rocks/features of the periods can be found in Shropshire.  Shropshire is a very geologically diverse county and if you look hard enough you can find examples from all of the time periods except for the Cretaceous (though the Tertiary is a little dodgy) .  I will say that the examples I am giving are not the only ones to be found in the county.  There are many other formations, rock types and sites that can be used to represent the time periods, I’ve just pick a selected few.  So prepare for a few explanations and quite a lot of pictures.  Just as a remind ma stands for millions of years ago.

Shropshire’s Geological Timeline

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Shropshire Base Map 1

 

I’ve included a brief timeline and a small map giving the rough location of the sites I visited (blue circles) with the major towns in the county for reference.

Quaternary Period (2ma to present)

As we are still living in the Quaternary then many landforms can be seen to represent what has and is still going on in the county.  For a more pre-historical landform a good example would be the glacial relics, of which the kettle holes and peat bogs around Ellesmere would be a good place to start.

DSCF2941DSCF3579These features were formed after the ice of the Devensian Glaciation retreated around 11,000 years, leaving layers of sand and gravel (commonly called glacial till).  The kettle hole forms when a block of ice falls of the retreating glacier and melts, leaving a water-filled depression.

Neogene, Paleogene and Cretaceous Periods

Sadly these formations are missing from Shropshire.  There is rumour of a Tertiary (possibly Neogene) outcrop near Whitchurch, but I haven’t been able to confirm it and I can’t find it on a map, so for now it’ll have to remain a mystery.

Jurassic (200 to 145ma)

You’ll be lucky to find this one.  There is only one real outcrop of Jurassic age rock in the county and that is around the village of Prees, about 5 miles south of Whitchurch.  There is some Jurassic bedrock under the layers of glacial till, but Prees is the only place it comes to the surface.  You can see one exposure, just east of the A49.  To get to it you can follow a public footpath.  The rock is mudstone from 183-190ma and the environment was once a shallow, tropical sea.

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Triassic (252 to 200ma)

The Triassic and Permian are both present in Shropshire, but the exact boundary has caused a little confusion in the past.  This is largely down to the similarities in the formations and the fact that they rest one on top of the other in the same locations.  Personally I think the best place in the county to see both Triassic and Permian is around Bridgnorth, though there are some other impressive red-rock formations that form several ridges in the north of the county.  The Triassic rocks are to the east of Bridgnorth, further up the hill and form part of the Kidderminster Formation.  It is mostly made up of red sandstone and conglomerate.  The image below is that of an exposure on the A442 near Allscott, just north of Bridgnorth and shows a layer of conglomerate sandwiched between two layers of sandstone.  It is a good example of cross-bedding between the strata and is representative of a river running through a desert environment.

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Permian (299 to 252ma)

As I said in the Triassic section, Bridgnorth is the place to see Permian rocks, in fact most of the town is built on it and some of the older buildings are made from it.  The Permian sandstone is also red, shows cross-bedding as the result of wind-blown desert sand, but seems to be a little tougher.  My Triassic samples half crumbled as I was extracting and transporting them.  Again the ancient environment was a desert.

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Carboniferous (359 to 299ma)

For the Carboniferous Period I’ve chosen something a little special; the Tar Tunnel.  Unlike my other choices this is something of a minor tourist attraction and as such will require the parting of a couple of coins.  It’s found in the east end of the Ironbridge Gorge.  The rock in the surrounding area is a mixture of limestones, coals, sandstones, mudstones, and conglomerates from the late Carboniferous Period.  When the Industrial Revolution was in full swing in Ironbridge a tunnel was built to act as short cut between the mines and the River Severn.  Upon digging the tunnel the walls started to ooze natural bitumen.  This was then extracted for a number of years before the industry moved on.  Is there likely to be an oil rush in Shropshire?  Not likely but it is an interesting phenomenon and one that I don’t think can be seen anywhere else in the UK.  If like me you are a ‘geo-geek’ it’s worth seeing.

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If it was red you’d think you were in a cheap horror movie.  The image below shows an pool of tar in a side chamber.

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For a more mundane sample from further up the gorge (Jigger’s Bank) you can see an exposure of the Lydebrook Sandstone.  This layer is made up of a pebbly sandstone and includes layers of conglomerate, and was what I used in the geological timeline above.

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Devonian (416 to 359ma)

Devonian rock actually forms the bulk of Shropshire’s tallest hill; Brown Clee Hill (not to be confused with the neighbouring Clee Hill or Titterstone Clee Hill).

Below is an image of Brown Clee Hill taken from the Wenlock Edge.

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Silurian (443 to 416ma)

The Silurian is very well represented in Shropshire.  One of the best formations in the county (and possibly the country) to see rocks of Silurian age is the beautiful Wenlock Edge.

The Edge is an escarpment that runs for almost 20 miles in a north-east to south-west direction and is made up of of a knoll-reef limestone with lime-rich mudstones & shales surrounding it.

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There are numerous walks along the Edge and due to the old (and current) quarrying activities there are plenty of places to see the local geology.  The above picture showing some wonderfully defined bedding planes.  It is also a good place to go fossil hunting.  There are several places both on and under the Edge were you can collect some nice samples like the one shown below.

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Ordovician (488ma to 443ma)

Like the Silurian the Ordovician Period is well represented in Shropshire, but I’m going to go for a well known formation; the Stiperstones Hills.  The Stiperstones are made up of quartzite and like the Wrekin Quartzite is a misnomer as it is a hard, white sandstone and not a metamorphic rock (like true quartzite is).  The Stiperstones have the added advantage that besides the Ordovician rock, you also have the tors formed from millennia of ice/frost shattering.

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Cambrian (542ma to 488ma)

The Cambrian witnessed a massive diversification of animal lifeforms (often called the Cambrian Explosion) and there some good locations and rocks to be seen in Shropshire.  The Ercall quarry has some wonderful quartzite to sandstone formations, showing beach ripples, conglomerates and inclined strata (see my Ercall post for more)

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The Wrekin Quartzite gives way to the Comley Sandstone.  The type site is the sadly neglected Comley Quarry (located on the north-east slope of Caer Caradoc) where Shropshire’s first Cambrian trilobites were found.  Unfortunately the rock faces are now overgrown and difficult to see.  It can be seen in better condition a the Ercall.

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Precambrian (4600ma to 542ma)

Being such a long eon the Precambrian goes from the formation of the earth to around 542ma.  The Precambrian rocks in Shropshire are mostly from towards the younger end; around 570ma with the gneiss and schist of Primrose Hill possibly being older.  My choice for the Precambrian is the Uriconian Volcanic formation which makes up a number of hills, including the Wrekin, Caer Caradoc and the Lawley.

This photo was taken from the Long Mynd (itself a sedimentary formation from the Precambrian) showing Caer Caradoc (centre right), the Lawley (centre left, and a bit in the distance) and on the left horizon is the Wrekin.  These hills are made up mostly of rhyolite, andesite and basalt.

Below is a sample of basalt from the Wrekin.

IMG_1862Well there you have, a brief geological tour of Shropshire.  The county has seen volcanoes and beaches, deserts and tropical seas and now the efforts of an enthusiastic geo-geek.  Hope you enjoy.

 

Pistyll Rhaeadr – Fantastic Welsh Waterfall

With a rare day of sunny weather in Shropshire I took the opportunity to visit a place I’ve been to on a few occasions and I’ve thought I’d share a few images of today’s trip, plus those of the past.

Pistyll Rhaeadr (I confess to not knowing how to pronounce this properly as my Welsh is rather poor) is a wonderful, yet little known waterfall in north-east Wales, about 10 miles west of Oswestry.  Apparently it is the highest single dropping waterfall in Wales, and though it is no Niagara the area is a beautiful place to walk and you can get both underneath and to the top of the falls.

DSCF4344The main waterfall has two drops; the higher set dropping into a deep plunge pool, which sadly is accessible due to the sheer drop to get to it.  If you’re feeling brave you can take a path to the left of the falls.  TAKE EXTRA CARE WHEN WALKING AROUND THE FALLS, SOME OF THE PATHS ARE NARROW, THE ROCKS CAN BE WET AND THE DROP…WELL YOU’LL HAVE ENOUGH TIME TO THINK OF YOU’RE LIFE BEFORE HITTING THE BOTTOM, YOU HAVE BEEN WARNED.  Now that the boring warning is given…

Location & Access: The falls are easy to access, though you might take a bit of time finding them on a map.  They are located at around 52*51′ N, 3*22′ W.  The only way to reach them by road is to travel to the village of Llanrhaeadr-ym-Mochnant on the B4580 and then take the narrow road (with passing places) you to the falls.  The road ends at the falls so you can’t miss it.

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There is a cafe and a carpark (£2 charge for the day) at the base of the falls, though a few hundred metres down the road there are a few places that you can park for free.  There are also toilet facilities on site.  Access to the base of the falls is good; there is a wide path with a gentle incline that should be no problem for most visitors.  This leads to a bridge over the stream that gives you a good view of the falls.  If you want to get to the top of the falls there is a path to the right, over some stiles and a steep walk up to the top of the hill.  This may be difficult for people with restricted mobility.

River Features: Pistyll Rhaeadr has many of the classic features you’d expect at a waterfall and an upland stream.  There are a series of plunge pools at the base of the falls.  Just watch out as you walk over the wet rocks…I couldn’t sit down properly for 6 weeks after I fell over whilst crossing here once.  You can see potholes and the eroding river bed.

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At the top of the falls you get a great view of the valley, a remnant of the time when glaciers once carved out the landscapes.  The steep sided valley displays evidence of hanging valleys as well as the remains of glacial debris, though now heavily farmed over and not as evident as other parts of Wales.  The geology of the surrounding hills is that of the Llangynog Formation – a series of mudstones with a band of tuff approximately 457-459 million years old (Ordovician period).

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One of the more unique features is that above the half-way plunge pull is a section of fallen & eroded rock that forms a ‘bridge’ across the stream before the water falls over again.  Sadly you can’t reach it, just admire it from afar.

DSCF4345The whole site is a fantastic place to spend a few hours if you’re ever near Oswestry.  The hills are beautiful and the falls are some of the best in region.

 

The Ercall

Due to some technical issues with my computer I haven’t posted anything in a few weeks.  Now I’m back up and running I plan on posting on a more regular basis.

Today’s monologue is about a fantastic geological site next to the Wrekin; the Ercall.

Location: The Ercall (pronounced ar-cal) is just north of the Wrekin in Shropshire, at around 52*40′ North, 2*31′ West, less than 1 km south-east of Junction 7 of the M54.

Access: The Ercall is open to the public at all times and access is easy.  There is a well maintained path and for the main quarry the gradient is low.  Other areas of the hill can be a little steep so if you have any mobility issues then they may be a little difficult to reach.  You can walk or scrabble over pretty much the whole hill as there are multiple small paths coming off the main track.  There are several small quarry holes as well as the main quarry and the whole place is worth exploring.

Geology: The various quarries in the Ercall are a fantastic place to see several geological features.  WARNING: wear a hard hat if you going to get close to the cliffs as there is the risk of falling rocks.

The featured image above is in the main quarry and shows a feature called an unconformity; specifically a nonconformity.  This is were there is a break in the rock sequence.  A nonconformity is the boundary between an underlying layer of igneous or metamorphic rock and an above layer of sedimentary rock.  In this case the igneous rock to the left of the image is an orange-pink coloured granophyre.  This is related to the Uriconian volcanics and is about 560 million years old.  The rock to the right of the picture is a pale grey Wrekin Quartzite and is about 533 million years old.  It is one of only a few places in Shropshire that you can see Cambrian aged rocks.  The Wrekin Quartzite is a bit missed named as a true quartzite is a metamorphic rock not a sedimentary one as found into the Ercall.

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The above image is a close up of the nonconformity.  Mixed in amongst the quartzite are several layers of conglomerate (see below).

DSCF4925To the east of the the nonconformity the quartzite mixes with the Lower Comley Sandstone and you get some impressive examples of a sedimentary bedding planes.  These are well jointed and are an excellent example.  These bedding planes have been lifted and incline downwards to the south-south east.

DSCF4916There is one more geological gem (figuratively speaking) to be found at the Ercall; ripples.  Mixed in in the layers of conglomerate are some wonderful examples of ripples.  These can be found higher up at both the west and east sides of the main quarry.  The ones to the west are in slightly better condition.  They can best be seen on a slightly cloudy day, just after it’s rained as the light & shadows more clearly define the ripples.

DSCF3340DSCF3354Combining this with the conglomerate, sandstone and quartzite gives us the origin of these rocks; an ancient beach.

For such a small site the Ercall really does have a wide range of geological features that can be seen really easily.  They’re great examples of nonconformities, bedding planes and ancient beaches.

Other Stuff: The Ercall is a nature reserve operated by the Shropshire Wildlife Trust, and a wide range of wildlife can be seen. There is a mixed deciduous forest with a small  stream running through it.

DSCF4881In spring the forest floor is covered in bluebells.

The local animal life is typical of a British woodland.  You can see finches, woodpeckers, Nuthatches, Treecreepers, Common Buzzards and if you’re really lucky a Peregrine Falcon.  It is a great place for a casual walk and has some wonderful geological sites to see.

Reference: Geology of Shropshire (2nd Edition) by Peter Toghill (2006), Geology (2nd Edition) by Stanley Chernicoff (1999).