The unconformity gets its portrait taken
Callan recounts a little lesson in taking a photograph of an outcrop that expresses itself more readily to the novice eye.
unconformities
An unconformity at Bacon Cove, Newfoundland
At Bacon Cove in eastern Newfoundland, there is a nice example of an angular unconformity between Ediacaran and Cambrian sedimentary rocks.
Friday fold: Point Arena, California
It’s Friday, and I’m grateful that Bret Leslie of the NRC has stepped up with a Friday fold contribution from coastal California: Bret says this outcrop is: from my trip last month to the Sonoma and Mendocino coast. The first is the cliff below the Pt. Arena lighthouse. The marine deposits (now a marine terrace) … Read more
Mafic volcanics atop felsic instrusives: Sonora Pass, California
Sonora Pass, California, is a lovely place to examine a volcanic-on-plutonic nonconformity that spans about 80 million years of missing time. Let’s check it out on a photo-rich virtual field trip!
Oddball Icelandic rocks, part I: A green ignimbrite
Iceland does basalt really, really well. But there are a few non-basaltic igneous rocks to be found there, too. One of them is a green ignimbrite (pyroclastic conglomerate) that crops out in coastal Berufjörður, eastern Iceland. Check it out!
Northwest Highlands unconformities (3 of 3): Sub-Ardvreck
It’s time to cover the third and final unconformity I observed this summer in the North-West Highlands of Scotland: the unconformity between the Neoproterozoic Torridonian Group below and the Cambrian Ardvreck Group above. Where I saw it, south of Loch Assynt on the mountain called Beinn Garbh (north of Canisp), it actually is displayed alongside … Read more
Northwest Highlands unconformities (2 of 3): Sub-Torridonian Group
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
Northwest Highlands unconformities (1 of 3): Sub-Stoer Group
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.
Friday fold: Siccar Point video from BGS
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
The New Market / Lincolnshire contact
Yesterday, I put a photo up here on the blog, and asked you to figure out where the formational contact was in that image. Here’s the image I showed you: It turns out that my plan to have readers upload their copies of the image didn’t work as well as I had planned – apparently … Read more