Thursday May 12th 2016
Ten pictures from the North West Highlands Geopark that will make you want to become a Geologist
Last week we shared an article from Geologyin.com entitled “10 pictures that will make you want to become a Geologist”, well as Maarten Krabbendam from the British Geological Survey pointed out it’s easy to come up with ten pictures from the North West Highlands Geopark that will make you want to become a Geologist. So here are ten of our favorites!
1. Folded mountains
Here we have some beautifully demonstrated thrust faults; these are caused by incredible tectonic forces which in this case have caused sedimentary rocks (quartzite) to fracture and piggy back up one on top of the other to raise up mountains. This mountain is called Arkle. By the way the racehorse was named after the mountain, not the other way round!!
Photo credit: Helen O’Keefe (NWHG volunteer geologist)
2. Amazing erosion features in Torridonian Sand Stone
At the coast wind and water weathers strange shapes into the billion year old sand stone, we think these ones look like catacombs but the geological term is Tafoni. They become particularly popular with climbers too who get a bit obsessive naming weathering features!
3. What’s in sand??
This is a thin section micrograph image of sand from Oldshoremore beach, it’s made up of fragments of Lewisian Gneiss, Torridonian Sandstone and sea shells. The thin section was made for our Beaches Exhibit at the Rock Stop, Unapool.
4. Multi-coloured rock stop, Laxford
The darker rocks are intrusions of mafic magma (called ‘Scourie Dykes’ ) into the Lewisian Gneiss (lighter rocks). This scene is at the side of the road near Loch Laxford and is known as the ‘Multi-coloured Rock Stop’. It’s part of the Rock Route and has some serious ‘wow factor’!
5. Trilobite Fossils
These critters were crustaceans, a bit like modern woodlice. They lived on the sea-bed and have left fossils of their bodies and tracks in the Fucoid Beds (a type of mud-stone rock found in the North West Highlands Geopark). Victorian Geologists gave the rock type it’s name, thinking the trilobite tracks were fossilised seaweed (the latin for sea-weed is ‘Fucus’), until they began to discover these 500 million year old creatures!
Image courtesy of GeoScenic (British Geological Survey) – photographer unknown . BGS © NERC. All Rights Reserved. 2016.
6. Swirls and Folds in Lewisian Gneiss
Gneiss is a metamorphic rock, as metamorphic as they come. This particular boulder, on the secret beach north of Achmelvich beach in Assynt has been squeezed (to produce those lovely bands) and folded tightly (making the swirly pattern). It’s been dyed orange by long gone, iron rich Torridonian Sandstone which once overlay it but has now been scraped away by thousands of years of glaciation.
Photo from one of our Geotours last year
7. Inselbergs and Roche moutonnées
One of the best places to view one of the most glaciated landscapes in Britain. From the summit of Beinn an Eoin in Coigach you can see how glaciers have carved out the Torridonian Sandstone, creating these unique shaped mountains known as Inselbergs and Rouch moutonnes. What better time than in winter to imagine this process?
Photo by Will Copestake
8. Limestone Caverns
The Great Northern Time Machine is a chamber as large as the Usher hall in Edinburgh. A large proportion of the Geopark is made up of Limestone, creating fertile soils and vast cave systems . This photo shows the smooth ‘flowstone’ made up of calcium carbonates which are dissolved as ground water flushes through the cave systems and re-precipitated into smooth sheet like rock. The Grampian Speleological Group have been mapping these caves, working closely with Scottish Natural Heritage.
Flowstone in The Great Northern Time Machine, by Hugh Penney, Grampian Speleological Group
9. Pipe Rocks
These bizarre tubular features in this slab of quartzite are actually worm burrows, filled in with white-ish sand as a rag-worm like creature burrowed into pink-ish beach sand at low tide half a billion years ago!
Image courtesy of Helen O’Keefe – NWHG volunteer Geologist
10: A thin section micrograph of Lewisian Gneiss
Responsible for our Cnoc an Lochan landcapes in the North West Highlands, Lewisian gneiss is one of the oldest rocks in Europe. Measured at Three Billion years old it has been seriously messed about with over time, being squeezed, heated and moved about deep underground. The bands you see in this thin section are tiny long thin mica crystals which have been forced to line up under pressure. You can see them grouped together with the naked eye as bigger banded layers in the gneiss. Who wouldn’t enjoy looking down a microscope at this as their day job?
Image courtesy of the British Geological Survey via GeoScenic. BGS © NERC. All Rights Reserved. 2016. Photographer: E.K. Hyslop.