A Week At The OVT: Day 3

If you are wondering how a day involving a swing off the roof of the Earth could possibly be topped, then continue reading. For the record, I’d like to say that a day like yesterday can easily be trumped – provided that (a) you are a rock nerd and (b) you have great colleagues.

Be prepared to use your thinking hardhat, and I warn you: there’s some hard-core science ahead. However, I’m sure you’ll love it, or at least be used to it by now. After all, my life: rocks!

Tl,dr: Today was a full day in the field. It involved studying pyroclastic deposits; identifying historic andesite lava flows; finding half-buried houses; walking up a volcano on land almost more recent than my last haircut; and the most beautiful road in the world.

Here’s a photo tour of my day.

1. Pyroclastic flow and fall deposits, by Banos Bridge

Tephra fall deposit (dark band) separates pyroclastic flow deposits.

This is a great outcrop just west of Banos. The fall deposit (dark band) is well-sorted, and shows some gradational bedding (fining upwards). It separates pyroclastic flow and surge deposits, which are far more poorly sorted. Both the lowest pyroclastic flow and the fall deposit above it seem to have created an effective topography, which the first pyroclastic flow event above the fall deposit has filled in. The series of gradational clast sizes you see above the dark band illustrate a series of successive pyroclastic flows; there are at least three.

2. Difference between flow and fall clasts (from previous outcrop)

Clasts from pyroclastic flow (left) and tephra fall (right). Differences
in internal colour and degree of vesiculation.

3. Colonnades and entablature in historic lava flow, north of bridge into Banos

Beautiful andesitic lava flows.

Amazing columnar jointing in historic andesitic lava flows. This outcrop may represent two different events, with different morphology created from shear forces. However, they could be from the same event, with the lower, straight columns the colonnade, and the upper, entablature.

4. House destroyed by pyroclastic flow from eruption 16th August, 2006

‘Seriously, you need to hoover this place. It’s disgusting.’

This house was destroyed by an ash-and-rock-laden gas cloud; believe it or not, there’s another storey under the earth here. More unbelievable, the neighbour’s house, 25 metres along the road, only suffered light ashfall. The house is still inhabited, and has an impressive collection of dirtbikes outside.

5. Daniel with rock – who won?

Answer: the rock.

6. The awesome power of a pyroclastic flow.

Between a rock and a lahar place.

The foreground shows a complete block of lava with autobrecciated a’a’ top and internal shear flow features below; this block is about 1.5 metres square and was carried down the volcano by the pyroclastic flows on February 1st, 2014. Shows the incredible power of the volcano! Tungurahua’s summit is in the background: covered in cloud, 3000 metres above.

7. Looking north to OVT, with recent landslides. 

Straight up, these landslides are HUGE.

We’re at about 2100 metres altitude, looking directly north into the valley where the Observatorio del Volcan Tungurahua lies, just outside the village of Guadalupe. The landslides are enormous, several hundred metres high; they regularly take out roads around this area.

8. Tungurahua in cloud.

How do you hide a mountain?

This was taken at 4pm, at the end of the most beautiful road ever. Banos to Bilbao and beyond, via Chimborazo Province.

Things you didn’t see, because I didn’t take pictures: a dumper truck full of children, a footbridge with no feet, dust storms in a rainforest valley, a wildly outrageous gorge; two road bridges destroyed by liquid earth.

Thanks to Liz and Daniel for a brilliant day!

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