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25 March 2019

The End, by Phil Torres

I’ve been fortunate lately to get to meet and interact with Phil Torres, independent scholar of existential risks. At my prompting, Phil came to a GSW meeting where Peter Brannen was talking about mass extinctions, and later he came to my class to talk to my Historical Geology students at NOVA about risks humanity faces. I figured it was about time I read his books, and now I can report …

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22 February 2019

Friday folds: Sardinian tuff

It’s the last day of the work week. Some photos of isoclinal syn-depositional folding in Sardinian tuff will get your Friday off on the right foot.

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8 January 2019

Geology of the Galapagos Islands

Dozens of delectable geological images from the Galapagos Islands, showing fluid basalt flows and violent pyroclastic deposits along with many primary volcanic features (and a bit of sedimentology thrown in for good measure).

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5 June 2018

Cross-bedding in Archean komatiitic ash deposits

Cross-bedding isn’t just for modern sedimentary deposits; you can find it in truly ancient ash deposits too! Let’s head to South Africa and take a look.

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12 January 2018

Friday folds: Hayden Butte (“A Mountain”), Tempe

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 the locals call “A Mountain.” Not “a mountain,” but “the mountain called ‘A‘.” It has …

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1 December 2017

People and Pyroclastics: Mount Agung at the Confluence of Science and Society

A guest post from an American expat living in east Bali, displaced with his family from their home due to Mount Agung’s recent eruption, and trying to help out as best he can.

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22 September 2017

Friday fold: bend in a vesicular lava flow, Etna

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 this feature), but I think we can appreciate it regardless:

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15 July 2017

Flow-banded rhyolite from Vulcano, Italy

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 sample on Twitter yesterday on the occasion (supposedly) of “International Rock Day”: For #InternationalRockDay , …

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1 May 2017

Accretionary lapilli from Archean volcanic eruptions

Volcanic “hailstones” called accretionary lapilli rained down on South Africa 3 billion years ago, and have survived to be seen in the present day, along the R40 road through Barberton Mountain Land, near the Bulembu border crossing into Swaziland.

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26 April 2017

Pseudocraters at Lake Mývatn, Iceland

Near the southern end of Lake Mývatn, astride the Mid-Atlantic Rift in northern Iceland, lies a field of “pseudocraters” that result from steam explosions beneath a fresh lava flow. Put on your head-net and join us to check it out!

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