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19 October 2016
Oddball Icelandic rocks, part III: conglomerate
At the Volcano Museum in Stykkishólmur, I learned that Iceland has fossils. Specifically, they have a display of bivalve (clam) fossils there, and when I asked where to find them, I was directed to a point further east on the Snæfellsnes Peninsula. The next day, I set off to find them. Here was what I saw on a cliff high above me, at the spot nearest to where I thought …
21 September 2016
Stađarbjargavík
Based on this photo, what do you think Stađarbjargavík might have to offer? If you guessed columnar jointing in basalt, you’d be right! Looking down the fjord, south of Hofsós (in Iceland): The place is basically a series of miniature Giant’s Causeways, full of unpopulated exemplars of cooling columns! Little coves separate the small peninsulas, each filled with rounded column bits: Here’s a spot where one more is about to …
15 September 2016
Pillow basalts from eastern Washington: a 3D model
Since I showed off some Icelandic pillow basalts yesterday, today I thought I would showcase a new 3D model of big pillows in Columbia River basalt of eastern Washington, taken from a photo set I made when I was out there in May:
14 September 2016
Pillows in Icelandic basalts
Time is short these days, but I know you hanker for amazing geology. How about some pillow basalts from the Snæfellsnes* Peninsula, far western Iceland? Note the cm-demarcated pencil for scale. See if you can find it in the GigaPan version below: Link Handheld GigaPan by Callan Bentley, stitched with Microsoft ICE _________________________ * “Snay full snooze”
1 September 2016
Archean microbial mats in the news and in GigaPan
The news yesterday of 3.7 Ga stromatolites in Greenland prompts a closer look at 3.22 Ga microbially-induced sedimentary structures in the Barberton Greenstone Belt’s Moodies group sandstones.
31 August 2016
Ball & pillow and other sedimentary structures in Graafwater Formation, Table Mountain
In Cape Town for the International Geological Congress, Callan hikes up Table Mountain and finds some superb primary sedimentary structures in sands and shales of the Graafwater Formation.
2 August 2016
Oldest fossils in the UK: M.I.S.S. in Stoer Group, Scotland
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 “Split rock” — Go figure. The Split Rock is an easy landmark to steer toward …
30 June 2016
Virtual field trip to Siccar Point, Scotland
Time for another virtual field trip on the Geologist’s Grand Tour of the United Kingdom: the most famous outcrop in the world. Today, we visit Siccar Point, Scotland. You’ve probably already seen photos of this place – they usually look something like this: To those who aren’t familiar, here’s what going on: There are two sets of strata here – and the contact between them is an ancient erosional surface. …
25 June 2016
A virtual field trip to the Giant’s Causeway, Northern Ireland
Some of planet Earth’s best examples of basaltic cooling columns are found at the Giant’s Causeway in Northern Ireland. In this post, explore four different kinds of interactive digital media as a way of experiencing the Causeway virtually, from the comfort of your computer.
17 June 2016
Friday fold: isoclinal flow structures in Icelandic lava
While soaking at some fine outdoor hot springs in southern Iceland (near Höfn) last week, I spied a Friday fold on the rock wall above the hot pots: Iceland is not a place where we would expect to find ductile folds in already-lithified rocks, so I’m guessing that these are folds related to flow in the lavas as they erupted at the surface. Happy Friday!
Callan Bentley is Associate Professor of Geology at Piedmont Virginia Community College in Charlottesville, Virginia. He is a Fellow of the Geological Society of America. For his work on this blog, the National Association of Geoscience Teachers recognized him with the James Shea Award. He has also won the Outstanding Faculty Award from the State Council on Higher Education in Virginia, and the Biggs Award for Excellence in Geoscience Teaching from the Geoscience Education Division of the Geological Society of America. In previous years, Callan served as a contributing editor at EARTH magazine, President of the Geological Society of Washington and President the Geo2YC division of NAGT.