As noted previously, the old way of viewing gigapixel imagery is no more. But there is a new, better way. The GIGAmacro company has a better viewing platform that can be used either with images uploaded to their server or with pre-existing images that currently “live” at GigaPan.com. Here’s an example: a roadcut of limestone … Read more
A detailed examination of an elegant photo of the eastern front of California’s Sierra Nevada, from the perspective of the Alabama Hills. How many different geologic phenomena can be packed into a single image? Let’s find out!
In keeping with the Arizonarific theme of this week’s posts (thanks to my participation in the 2018 Structural Geology and Tectonics Forum), I thought I would wrap up my ‘geology of the Phoenix area‘ posts with a walk I took on my last day there. This was to what Google Maps calls “Hayden Butte,” but … Read more
A visit to Papago Park, north of Tempe, Arizona, reveals hanging wall rocks from the South Mountain detachment fault, a long way from South Mountain. Also, feast your eyes on these gorgeous red sedimentary breccias, interpreted to be landslide deposits from the Neogene.
This morning on Twitter I was reminded of komatiites, those “extinct” ultramafic lavas that were relatively common eruptions during the Archean. I’ve actually got a good number of komatiite photos to share from my time last year in South Africa’s Barberton Greenstone Belt. But since time is short this morning, I’ll start with a short … Read more
It’s the First Friday of Fall! Here’s a sort of fold to help you celebrate: a section through a ∧ shaped bend in a vesicular basalt flow from the eastern flanks of Mount Etna in Sicily. It’s due to volcanic lava flowing rather than ductile deformation of a pre-existing solid rock (our usual habit with … Read more
I collected only a single rock on my summer travels in France and Italy. (Those of you who know me will realize how extraordinary this low number is!) It’s a flow-banded rhyolite from Vulcano, in the Aeolian Islands north of Sicily a few weeks ago. It contains porphyritic vesicular basalt xenoliths. I featured a similar … Read more
My son and I hiked Compton Peak in Shenandoah National Park this morning, and saw these two lovely examples of xenoliths. The example above is small, but it shows clearly the difference between the coarse, felsic basement rock (Mesoproterozoic granitoid, comprising the xenolith) and the surrounding fine-grained dark green metabasalt of the Catoctin Formation (Neoproterozoic). … Read more
A basalt flow in Iceland shows both enticing pahoehoe and fractures with a Y-shaped intersection pattern. Comparisons to bread loaves and east Africa suggest a reason why.
On the western coast of Islay, Saligo Bay showcases turbidites of the Neoproterozoic Colonsay Group. The Smaull Graywacke shows Caledonian (late Ordovician) folding and cleavage superimposed on world-class graded bedding. There’s also a nice dolerite dike to examine.