Let’s now profile the next unconformity in the sequence of pulses of erosion and deposition recorded in the North-West Highlands of Scotland. For a reminder, here’s a cartoon cross-section through the four relevant units: Today, we’ll look at the contact between the Lewisian Gneiss and the Torridonian Group (Diabeg Formation), marked with a “2” on … Read more
First in a series profiling the three unconformities to be found in the North-West Highlands of Scotland. Today: the sub-Stoer unconformity as exposed at Clachtoll. Explore a Proterozoic buried topography topped with coarse, angular breccia.
The isle of Jura in Scotland is where George Orwell wrote 1984. It’s just across a narrow channel from the eastern side of Islay, where I spent four lovely days geologizing this summer. Looking across the gap, you can see a cluster of prominent mountains on Jura. These are the “Paps” of Jura, and they … Read more
This is the Split Rock at Clachtoll, on the shore of the North-West Highlands of Scotland. You’re looking out to sea, over the Minch. It’s the site that graces the cover of the excellent book A Geological Excursion Guide to the North-West Highlands of Scotland, by Kathryn Goodenough and Marten Krabbendam. “Clach toll” apparently means … Read more
A quick Friday fold here from the North-West Highlands of Scotland: These are Lewisian gneisses exposed on a headland northwest of the little outpost of Tarbet (where the Handa Island ferry departs from). I was out there in search of shear zones, but I found plenty of nice folds, too. There are two main folds … Read more
Yesterday I showed you two scenes, depicted in two photos each, that I saw on the beach at Machir Bay, Islay, last week. I suggested that it might be fun to compare and contrast them. Scene #1 was this: Scene #2 was this: Scene #1 is a place where aeolian (wind) currents were at work. … Read more
Here are two scenes, depicted in two photos each, that I saw on the beach at Machir Bay, Islay, last week. Compare and contrast them. Scene #1: Scene #2: What stories do these pebbles tell? Answers tomorrow…
When in Shetland, one of my first stops was the museum in Scalloway, and one of the ancillary benefits of visiting there is the castle next door: Scalloway Castle includes building stones derived from the local limestone – a Neoproterozoic unit that has recently been chemostratigraphically correlated with Snowball Earth cap carbonates elsewhere in the … Read more
I’m in the North-West Highlands of Scotland, enjoying spectacular geology and less-than-spectacular weather. I’ve been fairly productive on the GigaPan front, regardless, nipping outdoors when the weather permits to shoot outcrops and landscapes. One set I’m particularly pleased with is this suite of four images. They show the Archean-aged Lewisian gneiss, the oldest rock unit … Read more
When I took you on a virtual field trip to Kinkell Braes earlier this week, I didn’t mention that the sandstones are folded there, now did I? Let me remedy that omission now: That is a plunging anticline that you could actually take a plunge into: And here’s a syncline to match. Happy Friday. Hope … Read more
I came to Shetland for the rocks – but I’ve been surprised and delighted by the huge range of interesting coastal geomorphology to be seen here too. I’ve never seen so many sea stacks, wave-cut cliffs, and bayhead bars in my life. One that is so “classic,” so “textbook” that I couldn’t resist it, is … Read more
Walking along the shore east from St. Andrews, Scotland, along the seaside sandstones of Kinkell Braes, you encounter several extraordinary examples of geology. It’s a great place for the next stop on our Grand Tour of the geology of the British Isles. Here’s the scene: The first stop is a giant eurypterid trackway, potentially the … Read more
Check out this sandstone cobble I saw at Barns Ness – it comes bearing gorgeous trace fossils. Can you spot them? Lens cap for scale in all these photos. The next three are close ups of the burrows from the previous image: Plus two more, from other cobbles I encountered::
Thanks to the website ScottishGeology.com, run by Angus Miller, I learned of Barns Ness, a Mississippian-aged limestone fossil site on the shore not far from where we are staying at Dunbar. We ventured out there on Saturday afternoon, in search of fossils. The presence of the Dunbar Cemenet Works nearby is an indication that this … Read more
Dunbar, Scotland, is a nice little seaside town that also happens to be the birthplace of the conservationist John Muir. My family and I have been based out of here this week on our European geological GigaPan expedition. But on our first morning, upon visiting Siccar Point (which is nearby), I threw out my back, … Read more
The British Geological Survey just came out with a new video on Siccar Point, featuring some excellent drone video of the site (in very good weather!). In addition to the unconformity, one of the things you will appreciate about the video is an excellent end-on view of a plunging synform exposed just above waterline: You’ll … Read more
Today’s Friday fold comes to us from Alistair Knock on Flickr*, via Dave Schumaker’s Geology News Blog, where there is a daily Flickr feed of photos tagged with the word “geology”: Bigger version here. The fold in question, an overturned synform, is at a place called “Butt of Lewis” (the northernmost point on the island … Read more
Whilst searching the coastline of the U.K. for Where On Google Earth? #226, I found these lovely folds exposed in wave-cut platforms on the east coast of Scotland. I missed the actual location of the Google Earth screenshot (It was in Wales, and Anne Jefferson found it), but I’m happy enough to have found some sweet folds exposed in map view.
As with last week, I’m going to show you someone else’s fold today. This one should have strong resonance with most geologists, because it’s a fold in the tilted (and contorted) older strata exposed below the famous unconformity at Siccar Point, Scotland: I found this image on the British Geological Survey’s online repository of images, … Read more