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9 August 2017
A suite of new 3D models
A showcase of five new 3D digital models of awesome rock samples and outcrops, produced using Agisoft Photoscan.
21 December 2016
Stromatolites of Bunnahabhain
Remember the diamictite I featured here a few weeks ago, from Islay? It was the one that might be a Snowball Earth diamictite. Well, if you follow Snowball Earth science at all, you’ll doubtless be aware that the glaciogenic sediments are characteristically overlain by “cap” carbonates. There’s a stratigraphic successor to the Port Askaig Tillite, too – it’s called the Bonahaven Dolomite. Unlike what you might expect for a cap …
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.
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 …
28 June 2016
“Dunbar marble” at Barns Ness, Scotland
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 is the most extensive limestone outcrop in central Scotland. I set my field assistant loose …
10 June 2016
Green River Formation stromatolite – a virtual sample
Today concludes a weeklong run of virtual samples. For the past five days, I’ve been presenting examples of a visualization combination that leverages the advantages of the GIGAmacro system with the 3D ‘virtual sample’ perspective of the Sketchfab-hosted model: the same sample presented in both formats. Today, we finish up with a stromatolite from the hypersaline Wilkins Creek member of the Eocene-aged Green River Formation of southwestern Wyoming: Link GIGAmacro by …
29 March 2016
Four new GIGAmacro images
Here are a few new images I’ve been working on with my home-based Magnify2 imaging system from GIGAmacro. Archean basement complex gneiss from the Gallatin Range of Montana: Link (If this looks familiar, that’s because one of the samples I imaged with the Photoscan 3D modeling technique and published on Sketchfab the week before last.) Banded iron formation from Minnesota with ooids and stromatolites: Link Intrusion breccia: Link Blue Ridge …
9 December 2015
Thrombolites of the Great Salt Lake, Utah
I saw mention of thrombolites exposed along the shore of Antelope Island in the Great Salt Lake the other day in my Facebook feed; because the description cited a professor at Westminster College in Salt Lake City, I prompted my friend and colleague Tiffany Rivera, also a geology professor at Westminster, to go check it out and get me some bloggable photos. As it turned out, she already had – …
30 July 2015
Stromatolites of the Helena Formation, Grinnell Glacier Cirque, Montana
My favorite place to have lunch in Montana is at the Grinnell Glacier cirque in Glacier National Park. This is the dining room table: You’re looking at a bedding-plane-parallel exposure of Mesoproterozoic stromatolites here. Every few years, I’m lucky enough to hike up there with motivated students and share food atop this unparalleled view into the shallow seas of more than a billion years ago. Stromatolites are sedimentary structures that …
8 January 2015
Stromatolite at the Strasburg Museum
The other fossil I saw at the eclectic and haphazardly-curated Strasburg Museum was this stromatolite. Top view: Side view: Probably this comes from the Cambrian-aged Conococheague Formation, although the Beekmantown Formation (early Ordovician) is another possibility.
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.