Concerning Rocks

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Some years ago I had a passing interest in the abstract shapes and forms rocks can take. 

Recently I was out on the Aberdeenshire coast hunting photos with a friend, who, being impressed with the rocky coastline, wondered exactly where the Highland Boundary Fault emerged at its most north-eastern extremity.

After a bit of research (particularly exploring using the BGS‘s iGeology app), I tracked it to a small headland, Garron Point, beside the golf club outside Stonehaven.

From the outside it doesn’t look like much, but on closer inspection it is awesome.

There are actually two faults – a small one at the north-eastern end of Craigeven Bay corner with Garron Point, forming a small spur off the Highland Boundary Fault which clips the coastline from the town out to sea.

On the lowland side the bedrock is metabasalt, psammite and pelite (North Esk formation) – metamorphic bedrock formed around 461-485MYa in the Ordovician period. On the highland side is gritty psammite (Glen Lethnot grit formation) – around 541-1000MYa.

The fault itself can be tracked to a matter of a few feet – a view from beside one of the golf greens shows the junction of both faults, with a strip of incredibly deformed grey rock leading away some meters rather like a line of chewing-gum.

Some of the most impressive rock outcrops I know. Toward the top-right of the frame – those cliffs are tall, especially from below! – a small fault runs diagonally down to the spray of water and out the left side; from front to back, a line of deformed pale grey rock only a foot or two wide, twisted like chewing gum, marks the Highland Boundary Fault at its most narrow only metres away from its most north-eastern extremity on land, at Garron Point headland near Stonehaven. The gnarly shapes of psammite (metamorphosed medium-grained grey former sandstone) and micro-basalt are awesome.
  • Prior to metamorphosis, this used to be sandstone. Now it forms a medium/coarse-grained rock, pale blue-green in colour, along the line of the Highland Boundary Fault.
  • This boulder marks the intersection of two fault lines; a small one, running diagonally from top-right to bottom-left, and the Highland Boundary Fault, running front to back. The zoom lens has compressed perspective, but for a sense of scale, the foreground rock in the right is maybe 15-20′ away.

My favourite image is an abstract closeup – purply-red microbasalt meeting gritty blue-green psammite in a spray of cracks and marbling lines.

Prints are available on my ShinyPhoto photo gallery: Under Pressure

Perhaps the clearest view into the workings of the Highland Boundary Fault I can think of. On the left, red-purple microbasalt (its fine cuboidal structure putting me in mind of streaky thick bacon); elsewhere the blue-green-grey of psammite and pelite, medium- to fine-grained metamorphosed former sandstones. All jumbled together with fine cracks and lines of marble hinting at the pressures involved.

Glen Clova

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A couple of years ago, a photo-friend and I spent a happy afternoon exploring Corrie Fee in Angus; I remembered emerging from the trees in an impressive bowl of a glacial corrie. In August, I sought to repeat the experience, starting from the carpark nearby, but in my haste to get off the ghastly Forestry Commission track (more like a hard gravel road ploughed through the forestry, complete with yellow metal gantries), I wound up taking a different path. It also emerges from the trees into a bowl of a glacial corrie, but felt different and I couldn’t work out whether it was the wrong exit from the woods or what.

Came home and checked the geotagged images to find it was not Corre Fee but Glen Clova instead. That would explain a lot of things! And unsurprisingly, I now use ViewRanger to navigate whilst hiking.

Still, a couple of hours bumbling around in the grass finding interesting photos in a dramatic bit of landscape on a moody afternoon… Can’t complain.

As I was stumbling around in the foot of the glen, I stumbled across this lovely little burn tumbling its way through the hillside:

The surrounding rocks are quite dramatic – I was amazed at the green and purple hues of moss and primitive plants growing on the crags around

And much as I know the forestry is entirely artificial now, it still drapes over the landscape like a cloak.

Loch Lomond: At Inversnaid

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There’s a couple of picturesque views to be had just below the hotel at Inversnaid harbour – the waterfall cascading down amongst the rocks one way, and opposite, a line of boulders leading toward the Arrochar Alps across Loch Lomond. Can’t complain.

I don’t often use the Pattanaik algorithm in LuminanceHDR, especially for colour results, but it seemed to work really well with the waterfall, nicely balancing low-key levels and saturation.

Crail: colour

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Three views of the beach at Crail – for the geologists, the rock is old red Devonian sandstone. For everyone else, the seaweed is slippery and the water is wet.

Arbor Low

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A few photos from a trip around Derbyshire.

Arbor Low is a Neolithic henge monument in the White Peak area of the Peak District, Derbyshire, consisting of about 50 local limestone boulders now mostly recumbent in a circle surrounded by a ditch and embankment.