In Shenandoah National Park, astride Virginia’s Blue Ridge, feeder dikes of Catoctin Formation (meta-)basalt cut across the Grenvillian-aged granitoid basement. Due to their mafic composition and columnar jointing, these feeder dikes generally weather more rapidly than their host rocks. I led a field trip in the park on Thursday for my son’s school, and my … Read more
One of my favorite places in Northern Ireland is the east side of the peninsula that hosts the tourist town of Portrush. There, two early schools of geological thought engaged in a battle. The opposing sides were: the Neptunists, who thought all stratified rocks, and in particular basalt, must form from precipitation from the sea, … Read more
Remember St. Ninian’s Isle? It is connected to Mainland Shetland by a tombolo. But it has rocks there, too. Here are some outcrops on the beach: If you visit these schisty fins, you’ll find they are populated by a cavalcade of small folds. Some of the folds are crisp things known as kink bands: Annotated … Read more
Take a look at these gorgeous exposures of augen gneiss in eastern “mainland” Shetland, U.K. Includes 3 GigaPans of the site.
The Friday fold is a guest submission from Bill Burton, who took the photo of these lovely ptygmatic folds in migmatite in a national park on the 100th anniversary of the founding of the Park Service.
It was five years ago when I first visited Sea Point, the outcrop on the coast of the Cape Peninsula where the Cape Granite (~540 Ma) intrudes the (meta-)sedimentary rocks of the Malmesbury Group. The outcrop is (a) beautiful and evocative, and (b) of historical importance, as Charles Darwin visited it while on the voyage … 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
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
Same beach as the Cushedun conglomerate post earlier in the week – but here we see the schist into which the rhyolite dikes intruded: It’s been folded! Happy Friday. Hope your weekend is rejuvenative and fun.
There are some folds in this stunning west Idaho landscape. Perspective is looking toward the north, more or less. See if you can find them: [gigapan id=”187745″] Link GigaPan by Callan Bentley One example that will probably be obvious at first glance is this syncline/anticline pair, differentially weathered, with subvertical axial traces, and an apparently … Read more