Friday fold: En route to Santorini over the Cyclades
A glimpse out an airplane window reveals some Cycladean geology in the Aegean Sea. Somewhere down there among the metamorphic rocks is our Friday fold… but nary a volcano in sight.
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Santorini: where the Hellenic arc meets the Cyclades
The geologic story of Santorini begins, with some tectonic perspective on the two major aspects of subduction recorded in the island’s rocks.
Sea arch in pyroclastic deposits, Santorini, Greece
A series of blog posts on the geology of Santorini and Athens, Greece begins with a look at a sea arch on the south shore of Thera.
Field work on the Grinnell Formation at Red Rock Canyon, Waterton Lakes National Park, Alberta
Callan’s Rockies field course students document faulting and jointing in Red Rock Canyon, Waterton Lakes National Park, Alberta.
Friday fold: Pleistocene glacial folding of Cretaceous sedimentary rock?
The Friday fold is found in Cretaceous rocks of eastern Alberta – but far beyond the tectonic influence of the Canadian Rockies. So what’s responsible for the folding?
An examination of the Horseshoe Canyon Formation in eastern Alberta
An expert on the deltaic depositional setting of eastern Alberta’s Horseshoe Canyon Formation shares field evidence and expertise with Callan’s students.
Friday fold: Buckle vs. passive folding in the Chancellor Group slates
The Friday fold is an outcrop in Yoho National Park that showcases differences between buckle folding and passive folding.
Guest post: Glaciolacustrine deltas in the Canadian Rockies
One of Callan’s “Canadian Rockies” field course students supplies a guest post about deltas that build out into glacial lakes.
Friday fold: the Castile Formation at the State line outcrop
The Friday fold visits the Permian basin of west Texas. There, the Castile Formation exhibits gorgeous inter- and intra-bed folding.
Ooh! Ooh! Ooids!
Ooids are fish-roe-shaped-and-sized spherules that result from the chemical precipitation of calcite from supersaturated water. Here are a few nice examples from Monday’s field trip.
Hunt’s Hole: Climbing ripples in volcanic surge deposits
Check out the immense climbing ripples preserved in surge deposits at Hunt’s Hole (a maar volcanic crater in southern New Mexico) and imagine the strong currents couples with an extraordinary amount of entrained pyroclastic material.
On ignorance, bias, data, and the tentative nature of (scientific) interpretations
A young-Earth creationist reinterprets one of Callan’s blog posts in light of a Biblical flood. Callan responds with a demonstration of how new information can change a true scientist’s mind, but no amount of data can convince someone whose conclusions are based on faith rather than empirical data.
The Story of Earth, by Robert Hazen
Callan reviews Bob Hazen’s latest book, “The Story of Earth,” a history of our planet that emphasizes the coevolution of minerals and life.
Annotating some Zion cross-bedding
A photo of the iconic dune cross-beds at Zion National Park gets the Bentley Annotation treatment, and comes out looking like a stained glass window. Take a look at both photos and see if you can answer the question, “Which way was the wind blowing?”
Mississippian invertebrates from the Lodgepole Limestone
On a cold winter’s day, Callan harks back to a summer’s afternoon fossilizing in the Rocky Mountains. A few choice images of Mississippian-aged marine invertebrates are shared.
Friday fold: Turtle Mountain and the Frank Slide
The Friday fold can be found this week at Turtle Mountain, Alberta, where it triggered a massive landslide.
Friday fold: mystery calc-silicate from the USGS
The Friday fold is a cast-off specimen from the USGS. A lovely little orphan, its marble and micaceous layers have polished up nicely. Two sides of the sample are presented here.
Monday macrobug: backstroking grub
The Monday macrobug is a juvenile beetle with an odd means of locomotion.
Friday fold: Sliced BIF from Joburg
The Friday fold is a trio of hand samples of folded banded iron formation from South Africa. Collected in 2012 as float from the “contorted bed” outcrop in downtown Johannesburg, these samples are only now being cut and polished in the lab at NOVA.
Friday fold: Kananaskis Trail, Alberta
The Friday fold returns to Canada this week, with a look at an internally crumpled mountain along Alberta’s Kananaskis Trail…