Some sweet “columnar jointing” style mudcracks from an abandoned quarry in about the farthest west corner of Texas that you can get to, or maybe the southeasternmost corner of New Mexico. One of them, anyhow… Did you spot the imposter?
New M.A.G.I.C. GigaPans are shown of two connected Hawaiian samples: one an igneous rock, one a loose beach sand.
How could thematically-linked images like these be used to further geoscience education?
Got any ideas?
Chime in!
A few scenes out the left side of the airplane from when I flew from El Paso to Houston a week and a half ago… Sand dune field overprinting desert vegetation and human roadways: Outcrop pattern of horizontal strata (tracing out the contours of this hill), and the weird geometry of human road systems: More … Read more
After seeing the contact of the Campus Andesite with Western Interior Seaway sedimentary rocks (Cretaceous in age), we moved a bit on down the line, and saw this disconformable contact between the Cretaceous shales below, and a bouldery sedimentary breccia above. Note the concave-up shape of the contact to the left of Elizabeth Nagy-Shadman (of … Read more
First thing we saw on the post-InTeGrate field trip to the rocks of El Paso, Texas, was this contact between the aforementioned Campus Andesite, and the Cretaceous sedimentary rocks into which it intruded (contact metamorphosed in the area of this photo): I decided to try switching up my annotation fonts. Whaddya think?
Had this brainstorm a few weeks back (or maybe months?). Been meaning to blog it up, but hadn’t gotten the chance to flesh it out. The geologic map of the Commonwealth comes from Chuck Bailey of William & Mary, who gave me permission to use it for this project. Anyhow – do you think there … Read more
This image has been in my “to blog” folder for more than a year: But here’s the thing – I can’t think of what I was going for when I drew this. The closest I can figure is that I was trying to illustrate conceptually what differentiates diamictites from other poorly sorted sedimentary rocks. Any … Read more
Why are these people smiling? photo by Yvette Kuiper Because they are structural geologists, and they are psyched to be at an extraordinary outcrop: This is a famous pavement outcrop of polyphase-folded banded iron formation (BIF) near Soudan, Minnesota. I went there last fall before the annual meeting of the Geological Society of America, on … Read more
Today, two examples of outcrops that reveal an overprinting relationship between metamorphic cleavage and sedimentary bedding. Both are Devonian in depositional age, from the new stretch of New Route 55 in West Virginia, west of Moorefield. The first is from limestones of the Helderberg Group, and the second is from shale of the Brallier Formation. … Read more
These are turbidites of the Malmsbury Group in South Africa, on the east shore of False Bay. A couple of nice little folds running sub-vertically through the package… Happy Friday!
Callan and his wife journey to Africa’s southernmost point, and find a geological mystery there.
After our safari, Lily and I were taken up onto the Great Escarpment in northern South Africa. The escarpment is supported by sedimentary strata of the Transvaal Supergroup that overlie the Archean basement rock of the Kaapvaal Craton. The Transvaal strata are Paleoproterozoic in age, somewhere between 2.5 and 2.0 billion years old. They are … Read more
Here’s a look at what you see if you go to the Three Rondawels viewpoint above the Blyde River Nature Reserve in northern South Africa: A lovely scene. The three mega-hoodoos on the left are the eponymous “rondawels” (pronounced ron-da-vulz), which is the Afrikaans word for a round hut. These erosional remnants are more or … Read more
One day in South Africa, Lily and I walked across Noordhoek Beach… Along the way, I noticed these little squiggles of sand: folded tube shapes. I decided I should photograph a few to share with Tony Martin, since he’s into trace fossils along coastal areas. Anyone have any idea what made these diminutive sculptures of … Read more
At the Three Rondavels overlook in the northern Drakensburg Mountains of South Africa, I saw this chunk of quartzite with a peculiar variety of Liesegang banding (iron oxide staining of the rock by groundwater): A short distance away, I found another example: In one key way, I liked this second example better, even though the … Read more
Callan reviews the geology of the superlatively auriferous Witwatersrand Supergroup of South Africa, and then zooms in on a distinctive marker bed near the base of the sequence. The deformation in this particular banded iron formation (BIF) is an aesthetic wonder, as this suite of images reveal. The layer outcrops in the heart of urban Johannesburg.
While I was away in South Africa, both Brian Romans of Clastic Detritus and Evelyn Mervine of Georneys posted pictures of folds in quartzite of the Cape Fold Belt in southern South Africa. Well, I’m not going to be left out. Here’s a belated Friday fold for December 23, showing a bunch of sweet folds … Read more
Today’s fold is an anticline and its neighboring syncline, both exposed along a newly-opened stretch of New Route 55, west of Moorefield, West Virginia. The new Route 55 is a classic porkbarrel boondoggle courtesy of the late Senator Robert Byrd, but doggone if it didn’t open up some lovely new roadcuts. Here’s a stitched image … Read more
Picking up from the astonishing first couple of outcrops we saw of strained Seine Group metaconglomerate from the boundary between the Wabigoon and Quetico sub-provinces of the Superior Craton, our group moved on down the road. It was lovely clear fall weather near Fort Frances, and shockingly warm. Our third stop of the morning was … Read more
Why are these geologists all over these rocks? Because, gentle readers, these are some seriously cool rocks. The geologists are all participants on a pre-GSA-annual-meeting field trip to the Superior Craton, a chunk of ancient crust at the “nucleus” of the North American continent. The rocks are syn-tectonic volcaniclastic conglomerates of the Seine Group. They … Read more