Two pleochroism animated GIFs
Biotite in granite: Riebeckite: Fast and slow versions of each. Wanted to post these ASAP, so someone can use them for the Geology Word of the Week…
Callan Bentley
Is “Tertiary” archaic?
Jack and Drumlin are visiting for the day from their usual home.
More earthquake damage
These are all in the northern stairwell between the 2nd and 3rd floors of the Godwin Building here on the Annandale campus of NOVA. The cement blocks have clearly separated along their mortared edges, and the disruption of the paint layer in a series of en echelon fractures reveals that deeper structural issue. I find … Read more
Clinker
“Clinker” is an interesting rock type seen in Wyoming’s Powder River Basin. It forms when a coal seam catches fire, and cooks the rock above and below it, including the potential for partially melting the strata immediately above. Check out a few images of this intriguing rock here.
A dismaying course, part II: evolution
Picking up where we left off on Thursday’s post on the relationship between the 2011 Republican presidential hopefuls and science, we examined their statements on climate change. Today, we look at the other information compiled by NPR, their statements on evolution. Michele Bachmann I support intelligent design. What I support is putting all science on … Read more
Friday fold: just Kidding
You’re looking here at Mount Kidd, a peak in the Front Ranges of the Canadian Rockies that displays a tight anticline/syncline duo superimposed on the strata of the Rundle Group. Located on the west side of Highway 40, the Kananaskis Trail, south of the trans-Canada Highway, this mountain shows us what happens with Carboniferous-aged carbonates … Read more
A dismaying course, part I: climate change
You may have heard that the Republican party has been embracing non-scientific and anti-scientific positions lately. National Public Radio compiled a bunch of quotations reflecting this trend on their website yesterday. I thought I might take a moment here on the blog to critique their statements (both pros and cons), and then reflect on why, … Read more
Another updated aftershock plot…
A up-to-date tally of the aftershocks from the Mineral, Virginia earthquake is presented as a time vs. magnitude plot.
Graded bed from the Billy Goat Trail
Spotted this one Monday on the newly-rerouted section of the Billy Goat Trail’s Loop A, in Chesapeake and Ohio Canal National Historical Park. This graded bed was deposited as a turbidite in the Iapetus Ocean, sometime in the time-frame of 700 to 460 million years ago. It was metamorphosed 460 Ma during the late Ordovician … Read more
Callan gets friendly with dinosaur
At the Sheridan College natural history museum, this past summer.
Two more macrobugs
It’s that kind of day. Grasshopper? Cricket? Katydid? Some kind of orthopteran, anyhow. Not a full adult, to judge by the lack of well-formed wings. And, here’s a yellow crab spider:
Macrobug: Unidentified caterpillar – UPDATED
Some kind of caterpillar I spotted on the Billy Goat Trail yesterday – can’t find a perfect match for it to identify the species. Anyone know? Chime in. UPDATE – My colleague Victor Zabielski pinned it as Schizura concinna, the redhumped caterpillar. Thanks, Victor!
Friday fold: duplex structure in the gastropod limestone
The Friday fold is a gorgeously deformed “duplex structure” in Mesozoic limestones of southwestern Montana.
Columns form perpendicular to cooling fronts
This morning, Dana asks about the pattern of columns in this image: She muses: If I had a time machine and surviving-fresh-lava gear, I’d head back to see what this bugger was up to. Why did some of its columns form ramrod-straight whilst others are practically horizontal, or curved? I’d imagine it was contending with … Read more
Updated aftershock plot
The USGS reports more aftershocks, so your humble graphing servant has responded with a plot that updates the images I showed you last week. Here you go: Embiggable, via a simple click. Again, the “decay” pattern jumps out at us. One thing that I’m also noticing is how there are no events below 2.0 magnitude. … Read more
Damage to the Ecuadorian Embassy
My wife Lily is an Ecuadorian citizen. She was born in Quito, and we have traveled there together. (She’s also a U.S. citizen.) After the big earthquake on Tuesday, significant structural damage was reported at several Washington landmarks including the Washington Monument and the Smithsonian Castle. Another one, less recognizable to most folks, but key … Read more
Animated GIF of Virginia quake aftershocks
So last Tuesday we had an earthquake, and we expected some aftershocks as the crust in the Mineral, Virginia, area adjusted to the new stress regime. We expected those aftershocks to be lesser in magnitude, and to take place after the main shock. In other words, we would predict the following: And, indeed, over the … Read more
Friday fold addendum
Lee Allison, State Geologist of Arizona and exemplar of public outreach via blogging, sent me an e-mail yesterday regarding that awesome coastal Greenland shot by Alistair Knock that I featured as the Friday fold. Lee, like many of you, found the image entrancing and intriguing, and as he explored the unannotated version, he made some … Read more
Why those curves, Rock Creek?
On Tuesday morning, before the earthquake hit, I answered an e-mail about DC faults. I get unsolicited e-mails all the time (and occasionally phone calls, too). The contact comes from people who have a geological question, find my blog, and figure that I might be willing to answer it for them, or to direct them … Read more
Friday fold: epic Greenland coast
The Friday fold is a beautiful straight-limbed antiform from coastal Greenland, courtesy of photographer Alistair Knock. Check it out and see if you can find anything that Callan didn’t annotate.