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Earth sciences news

1 Post tagged with the lava tag
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A team of geologists from the Museum and Imperial College are in Mexico carrying out  fieldwork at two of the most active volcanoes in the world: Popocatépetl (Popo) and Colima. Catch up with their adventures in this series of blogposts.

 

After our dirty but successful pumice-rich first week at Popocatépetl, we were all happy to get that dust off our shoulders and start chasing the various lava flows that make up most of the volcano edifice. Now, if the whole volcano is built by lava flows, it should be really easy to find these rocks, shouldn’t it? The short answer is: no. The longer, picturesque answer will take you into the wild, rough and bumpy world of Popo’s lower flanks, where a good rock is as hard to find as a sleeping baby lion in the vast African savannah. Join us on the magical ROCK SAFARI!

 

Early in the morning, when Popo is still entangled by the night’s misty claws, we make our way from the hotel in Amecameca towards the south-eastern flank of Popo, the land of the sneaky rocks.

 

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Somewhere down there they are hiding: the Popocatepetl lava flows!

 

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On the lookout for rocks: moving in this terrain makes you reconsider what you may call a ‘road’.

 

What makes it so difficult to find these lava flows is the fact that most of them are buried by a thick cover of the Popo pumices (not again!) and lahar deposits. So in many cases the only thing we can find on top of these dirty deposits are loose boulders of rock, which we can’t even be sure belong to the place we find them lying. A tedious job requiring lots of caution!

 

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An easy catch: can you spot the rock?

 

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Julie finds a rock that has tried to hide away from our hammers…

 

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…we took care of it.

 

Such a seek-and-destroy campaign can easily take a couple of hours for one lava flow and is not necessarily successful. However difficult it may be, when you finally spot a nondescript, lichen-covered rock specimen, the adrenaline you feel while smashing it into pieces to see what species it is pays off generously.

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Another boulder from a Popo lava flow successfully tracked down.

 

One factor that contributes to our (otherwise rather questionable) sense of adventurism during this rock safari is the daily recurrence of a group of local forest watchdogs roaming around the terrain. The first time they came, they only surrounded our car with a grim look on their faces, checking if we were hunters (if they could only know!).

 

The second time, they had machetes (they were cleaning the roads from vegetation) and we had to give them some money so they’d let us pass. The third time, it was already getting dark, and they had shotguns to guard a road against any people with mischief in mind. We certainly didn’t at this point. The good thing is that by now they know us and they greet us cheerfully every time we pass them.

 

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Obviously, we weren’t keen on photographing the shotgun watchdogs, so instead we present evidence that some lava flows are not good at hiding away. This the Nealticán lava flow, which is the most recent of Popocatépetl’s lava flows (in geological terms, ‘recent’ means younger than 2,000 years). Because of its young age, it is not covered by a lot of deposits and is thus widely exposed. Unfortunately, this flow is the exception to the rule.

 

In this manner, we have chased down a couple of lava flows in the past few days. We are very happy with the outcome of our rock safari and can’t wait to introduce these samples to their new temporary habitat while they are shipped to the UK: cardboard boxes!