Callan documents a geological stroll along the coast of Esterillos Oeste, in central southern Costa Rica, investigating the sequence of sediment in the Punta Judas Formation (Mid-Miocene) exposed there. Fossils, sedimentary structure, diagenetic features, structural deformation, and modern weathering all make prominent appearances.
A visit to a natural sandstone arch (or “bridge” as the locals call it) in eastern Kentucky yields unexpected bonuses, like fossil wood, Liesegang banding, and the honeycomb-like weathering pattern called “tafoni.”
A new edition of “science and nature question and answer.” This week: why Massanutten Mountain isn’t longer, and why you’re never going to walk on the Sun.
Back in 2011, when we were still living in D.C., Lily and I made a hiking trip out to Buzzard Rocks. It was a destination. Now that I live out here in the Fort Valley, I see Buzzard Rocks all the time, and I love it. It’s such a cool feature – a spot on … Read more
What hath the Potomac River wrought on the rocks of Mather Gorge? Some interesting shapes to the land surface reveal a fascinating history.
Another landform seen out the window of that very productive photo-flight last March: That’s a breached plunging anticline – doubtless a Laramide structure. This was over Wyoming; I think here. Looking north-ish, along the axis of the fold: Note that the lengths of section line A and B are not equal: this anticline is asymmetric. … Read more
A few shots from Fossil Falls, in the southern Owens Valley, California… This is the now-dry river bed of the Owens River. There’s abundant evidence of water-induced erosion (potholes, polishing, etc.), but nary a drop of water to be seen – Though this particular portion of the Owens River drainage dried up in the Pleistocene, … Read more
Rob Simmon of NASA’s Earth Observatory is the source for today’s Friday folds. Last week, he tweeted this image to me: That’s a excellent example of the outcrop pattern of a more or less horizontal outcrop of folded rock. To the north is a synform (notice that where streams have eroded it, the bull’s-eye pattern … Read more
My first view of Lion’s Head, the little butte northwest of Table Mountain, came through the fog on the morning that Evelyn and Jackie took Lily and I to Sea Point to see the migmatite: A lofty pinnacle – made of the same flat-lying quartz sandstone as the mesa of Table Mountain to the southeast: … Read more
Here are some photos out the window of my flight home from California the week before last… Snow on the north sides of mountains, but not on the south sides (view is from the south towards the north): Same thing here: And again… And again… it would appear that our route from Reno to Minneapolis … Read more
Some views from the airplane, over southern Wyoming (first two photos) and north-central Nevada (last four), last Saturday morning… A canyon: …and zooming in to the middle area of the previous photo: Strata upwarped into a structural dome (that has been “planed off” to be topographically horizontal, revealing a bull’s-eye-shaped outcrop pattern, then differentially weathered … Read more
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
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.
Callan embarks on an exhausting climb of a major summit in the Wyoming Bighorn mountains, a peak named in tribute of one of his geological heroes. Come join the trek to the top of Darton Peak!
On my hike to the Burgess Shale earlier this week, we encountered some great geology as well as paleontology. For instance, consider this rather epic alluvial fan, spilling out of the Presidential Range to the northwest of Fossil Ridge and Mount Burgess, and rapidly filling the Emerald Lake basin. Here’s a Google Map link to … Read more
Busy days here in DC and northern Virginia… Blogging time has been limited. A few more shots from this past summer’s time at Mount Washington, to fill the void… Prius atop mountain: The Great Gulf: Hikers in relatively warm weather: Another look down the Great Gulf: Glacial cobble of diorite, exotic to the top of … Read more
A week ago Saturday, my three Honors students and I went on a field trip led by Gary Fleeger of the Pennsylvania Geological Survey, to examine some cool glacial features in western Pennsylvania. The trip was associated with the joint meeting of the northeastern & north-central sections of the Geological Society of America, held in … Read more
The author recounts a field trip in October along the section of Turkey’s North Anatolian Fault that last ruptured in 1944. The rock types on either side of the fault are compared, offset markers are illustrated, and several types of landforms particular to strike-slip faults are shown. The post concludes with an examination of the town of Gerede itself, which is built directly atop the fault.
When I was done with my sophomore year at William & Mary, I embarked on a time-honored tradition among W&M geology majors: the Geology 310 Colorado Plateau field course. Jess alluded to this same course in her Magma Cum Laude contribution to this month’s Accretionary Wedge geology blog “carnival,” too. My version of Geology 310 … Read more