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.

Three weeks of amazing fieldwork at two of the most active volcanoes of the world have come to an end: Popocatépetl and Colima, you have been very generous to us, both in terms of large quantities of promising samples and impressive levels of activity. Now that we are back in London, we want to conclude this blog for the time being with some take-home impressions of our beautiful Mexican volcanoes.

As scenic and contemplative these pictures may be, all the steam puff, ash clouds and fresh lava streams are a constant reminder of the immense destructive powers slumbering within these giant volcanoes, posing imminent danger to its surroundings. Both Popo and Colima have shown increasing levels of activity in the last months, making detailed real-time monitoring as well as fundamental studies of the underlying principles of the volcanoes’ dynamics even more pressing and important.

Using the samples we collected during the last three weeks, we, at the Natural History Museum and Imperial College will work hard in the future to contribute to the understanding of how Popo and Colima work.

There is more fieldwork at Popo to come in the next years, and of course we will be covering these trips at this exact place again. Until then, enjoy the pictures and be sure to watch out for a forthcoming NatureLive event at the Museum’s Attenborough Studio, where we will be talking in detail about our exciting trip to Popo and Colima! Thanks for reading.

Popo as seen from Paso de Cortes: The wind blows the impressive steam plume to the NE.

Looking South: The mildly snow-capped Popo towers in a surreal way over the trees surrounding ‘La Cascada’ resort.

A last view from our hotel in Amecameca: Popo bids farewell to us with a nice trail of steam puffs.

The danger within the clouds: Fuego de Colima. Even through the cloud cover, one can make out the gases that are constantly exhaled from the summit.

The black lava flow in the center of this image has been emplaced during the last two years of activity of Fuego de Colima. The ‘clouds’ you can see here are actually gases coming from this lava flow, which is still hot.

Twin peaks: The steaming, several hundreds of degrees hot summit area of Fuego de Colima in the foreground, and its snow-capped older sister volcano, Nevado de Colima, in the background.

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.

This uncomfortably oblique photograph marks the end of this year’s fieldwork at Popo. As you can see, we have been extraordinarily successful in collecting samples:

All in all, we have collected twelve boxes full of pumice and lava in the last two weeks, each of them weighing about 20 kg!

Moreover, not only have we been doing well in bagging rocks, but we also made many important field observations, such as the relation of the different volcanic units in time and space. This is essential for the proper handling and analysis of our samples.

As soon as our heavy load arrives at the Natural History Museum, I will crush the rocks into tiny pieces and examine them using different types of microscopes. We are confident that this will tell us intriguing stories about how Popo works. The adventure has just begun!

But first, we will drive this trunkful of rocks to Mexico City, where we will also say ‘muchissimas gracias’ and ‘hasta luego’ to Julie, who will fly back to London, and also to Hugo and Guillem, who will stay in Mexico City. Chiara and me will stay in Mexico for another week, which we will mostly spend in Colima. There, about 500km West of Popo, the ‘Fuego de Colima’ volcano is currently very active, with several small eruptions every day. We are excited to go there and see some nice ashclouds, and of course, we will keep you posted about our ventures in West Mexico!

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.

Time flies – we've already been here for a whole week! While Popo was smoking and steaming like a champion, we dived deeply into the dirty, dark side of geology during this week: We sampled ash and pumice from the four large eruptions of the last 15,000 years. For hard-rock geologists like Chiara, Julie and me, this was a challenging task. So much dust, so few proper minerals! But if you want to understand how Popo works, this is simply what you need to go through.

Armed with shovels of various sizes, a tape measure, our geological hammers (you never know!), and, last but not least, a hoe (romantically referred to as the ‘mano de gato’ - ‘the hand of the cat’), we went out onto Popo’s flanks to search and exploit its volcanic deposits. Hugo, the Popo expert, unerringly navigated us to the top spots, where we then got to work. The following series of pictures reveals what this actually involved:

First of all, we need to get an overview about what we see. In this case, we are looking at the deposits of at least three large eruptions of the last 5,000 years. If you want to know more about such eruptions, just ask us!

Next, we describe the different layers we see. This includes the size and properties of the clasts, the structures, and the thicknesses of the units.

After that, we can start sampling. Sometimes it can be straightforward, sometimes you may need a helping mano de gato (‘the hand of the cat’) to clear the sampling site and guarantee a neat sample.

Some or all parts of the layers might be covered with soil or debris. In this case, the shovels of various sizes come into play. This picture demonstrates that in doing so you may excavate more than rocks, such as the rubbish of what apparently was a big Mexican Fiesta (including diapers and mayonnaise).

On other occasions, it might not be garbage, but a proper treasure that you dig out: A volcanic bomb! Hard-rock geologists, get your hammers and cameras ready!

And this is what you get if you repeat the above steps for a whole week.

Now, this might have all been a bit nerdy, so I’ll finish this blog entry with an almost completely unrelated note. Of course we are not only interested in rocks, but also in Mexican culture. Naturally, when a worker in a quarry (we were there by chance, obviously) told us that there was a man in the nearby town San Nicolás de los Ranchos who would craft wonderful molcajetes (pestle and mortars), we went there immediately.

On the way there, Hugo explained to us that molcajetes are mortars especially designed for making salsa. Did I mention that they are made of rock? This is also why the salsa made using molcajetes tastes different than if you just use a simple blender – the sauce takes up the taste of the rock.

With this salsa-lesson learned, we were all quite keen to see these wonderful items. But how would we find the Molcajete Man in the village? It’s easier than you’d think: you just ask anyone on the street for molcajetes. He/she won’t be able to give you a helpful answer, but 3 minutes later the whole village will know about the lost tourists looking for molcajetes. Out of nowhere, a random girl will appear next to your car, offering to bring you to Molcajete Man. Being a lost tourist, you accept the offer and follow the girl for about 30 minutes through the village, which gives you the opportunity to take some tourist pictures:

San Nicolás de los Ranchos is built on laharic deposits from Popocatépetl.

Evacuation routes are signposted all around Popo.

The presence of the volcano inspires local artists to draw their own conclusions on what happens in nature.

Finally, we reached the mansion of Molcajete Man. He looked different than I expected, but obviously he is a master of molcajeting.

Molcajete Man crafting a molcajete.

We would have really loved to get our own molcajete by that time, but these mortars are just way too big to transport to the UK. At least they are if you are already sending a garage full of pumice there.

Thus our pumice week has ended, and we enter phase two: rocks! I can already promise you it will be an exciting ride, so visit us again!

The Lyme Regis Fossil Festival took place in Dorset on 2-4 May 2014. Our palaeontologists Lil Stevens and Zoe Hughes report back from a weekend of sun, sea, fossils and fun.

Saturday in the festival marquee was a busy one with lots of people queuing to sieve for sharks teeth from Abbey Wood (which they got to keep!).

Charlie Underwood sieving for teeth.

Elsewhere Museum staff were also quite busy. Mark Spencer and the Angela Marmont Centre (AMC) team were talking about seaweed using samples which they had collected from the beach that morning.

Mark Spencer with some of his seaweed.

Emma Bernard’s shark measuring activity proved very popular - she had crowds of rapt people hanging onto her every word. People like big Megalodon teeth! Emma has also been busy tweeting for @NHM_FossilFish.

Emma Bernard with her popular shark activity.

Andrew Briscoe and Suzanne Hocking have been teaching people how to extract DNA from strawberries- incredible that this can be done in a marquee on the beach!

Andrew Briscoe and Suzanne Hocking showing us how to extract DNA.

In the rest of the marquee lots of other organisations had some great activities. Zoe Hughes discovered that she walks like a Velociraptor with Plymouth University and that she is as tall as an extinct fossil penguin from Antarctica with the British Antarctic survey.

Zoe has a look to see which penguin she is as tall as.

We've packed the car and we're ready to go to this year's Fossil Festival! The Museum will be in its usual place in the main marquee on the beach near the Lyme Regis Museum - this is my first trip to Lyme so it's all new to me.

I'm looking forward to the tropical climate and warm, shallow sea...oh no, that was in the Jurassic period. Forecast for this weekend: cool with occasional showers and the possibility of overnight frosts. Ah well, we're in a tent!

Museum volunteers Sam McCausland and Mike Smith pack the important stuff into the Fossilmobile.

This year we will be bringing anthropologist Margaret Clegg to talk about ancient humans, and palaeontologists Pip Brewer and Jerry Hooker to showcase some very ancient mammals.

You can sieve for sharks teeth with fish curator Emma Bernard and expert David Ward, and if you can find them you can take them home with you! They will also show you how to use shark jaws and teeth to estimate the body size of some of the largest sharks ever to have lived.

Zoe Hughes, our cephalopod and brachiopod curator and I will be explaining how palaeontologists reconstruct fossils to work out how the animals looked when they were alive. Test your palaeo-skills with our drawing challenge! Palaeontologists Martin Munt and Noel Morris are Lyme veterans and will be on hand to answer all your most technical paleontological questions - so you'd better think of some!

Those mysterious Museum mineralogists are planning a sparkling surprise so come down to the beach and see some very special pebbles...

It was our first day at the festival proper yesterday, and the weather was great!

We had a day of great interactions with local primary schools. Scientists from the Museum brought along a massive cast of a baryonyx skull, and visitors were invited to take a closer look at some microscopic life through one of our amazing scanning electron microscopes (SEM).

Cast of the skull of Baryonyx, a Cretaceous dinosaur with huge claws for hooking fish 

Other great exhibitors included:

• The Buckland Club, who invited the public to help excavate a model plesiosaur
• Rock Watch, running creative plasticine fossil workshops
• The University of Plymouth, who measured visitors' strides to work out which dinosaur they are most like
• a great collaborative artwork of the Jurassic coast, led by artist Darrell Wakelam

The fine art of fossil excavation

Here's hoping for some good weather this bank holiday weekend! More news from the learning team soon.

Posted on behalf of Emily, Ben and Jade from the Museum's learning team.

The Museum learning engagement team's first day at the Lyme Regis Fossil Festival ended yesterday and it was an epic day!

We were up at 6.30 to start at 8 yesterday at Thomas Hardye School, where five schools from the Dorset area participated in earth science related activities throughout the day. The team have been helping students investigate a dinosaur dig and identify what they uncover.

Jade assists a willing group of fossil hunters

Other activities included creating meteor impact craters and extracting copper from malachite using electricity!

Extracting copper from the mineral malachite

Scientists from the Museum brought lots of amazing specimens for the 450 students, including tektites, formed from sand rapidly heated by meteorite impacts and ejected to form these beautiful tear drops shapes.

A tektite (on the left) formed when sand is rapidly heated by a meteorite impact, with a pound coin for scale.

Other highlights included the biodiversity team's activity, where students identified bugs and other arthropods, contributing to important citizen science data. There was also a great stand featuring Thomas Hardye's very own Fossil Club, who were busy inspiring fellow students to get into fossils.

We finished packing up, headed to Lyme Regis to set up for the festival on the water front and today's primary school day, (and finished off with some well earned fish and chips!)

The festival runs from today until Sunday 5 May so if you're in the area come and join us and many other exhibitors for more earth science fun!

Posted on behalf of Emily, Ben and Jade from the Museum's learning team.

We’re here on a three-week trip to continue our explorations of the caves of Rodrigues. The south-western part of Rodrigues (the smallest of the Mascarene Islands) has a partial covering of calcarenite, a type of wind-deposited limestone, which is riddled with caves. This rock is locally known as ‘corail’, and is believed to have formed when the coral reef was exposed during a period of low sea level, and the coral sand blew inland, forming dunes, which later lithified (turned to rock).

The caves were formed by groundwater dissolving the rock, and they boast all the usual flowstone formations - stalactites, stalagmites, columns, curtains, straws, helictites, gours and crystal pools. Two of the more awe-inspiring larger caves, Caverne Patate and Grande Caverne (below), are open as showcaves, but we are here for the old dead stuff - the bones of the animals that lived on this remote island before humans got here. We tend to find bones in the sediment on the cave floor, but not always.

Grande Caverne, one of the larger caves inRodrigues

We are aiming to find the caves that were excavated by two 19^th century naturalists, George Jenner and Henry Slater, who were among the first to collect bones of extinct species in the caves. Unfortunately, Jenner delegated the work to his deputy, and he in turn ducked out of his duties, meaning that Jenner’s report is vague at best, and perhaps fictional at worst!

Slater’s account was not much better. Using these tatty shreds of evidence we are trying to figure out where these two teams actually dug. There is a point to this - Jenner’s collections were sent back toCambridge University Museum, and Slater’s are now in the Natural History Museum, London. We’d like to know which caves the bones came from.

So what lived here in the past?

Rodrigues is 534 km east of Mauritius, the home of the famous dodo, but its little-known cousin, the solitaire, lived on Rodrigues. This bird was also flightless, and succumbed to extinction for similar reasons - human arrival, introduced species and rapid changes to its environment, that began around 1730.

The Rodrigues giant tortoises were taken to provide meat and oil for long sea voyages and to supply the hospital in Mauritius (the oil of giant tortoises was believed to cure scurvy). This over-exploitation caused their extinction around 1795; just 70 years after the Mauritius giant tortoises became extinct for the same reason.

Many other species of bird and reptile on Rodrigues also became extinct. Some of them we know from contemporary accounts and from museum specimens that were collected while the species were still alive; others we only know from the bones left behind in the caves.

There were no mammals except for the fruit bats, which are still with us today, thanks to a massive conservation effort. Of the endemic birds, only the warbler and the fody have survived, helped by local conservation work. The sparrow that visits our dinner table and the gecko that patrols the house, are just two of the introduced species here. Goats, cattle, cats, dogs, pigs, chickens, ducks and turkeys are here too, and we find their remains in the caves.

Sieving cave sediment in search of bones, big and small

Island hospitality

In 2007 we helped to set up a small museum on Rodrigues. It is here that we are based, and where our finds will remain. We are staying with a local family, a short walk from the museum and most of the caves. They are feeding us very well, with local produce including fish, octopus, vegetables and fruit, washed down with bucketfuls of rice.

The cyclone season has just finished and the strong winds that were keeping the mosquitoes at bay have now dropped, so I am fighting my usual battle with them (helped by a good mosquito net called ‘Mosinet’ which I highly recommend!). Julian says that he only brings me on these trips so I can be the mosquito bait. However I think I have proved my worth this time…

Taking a well-earned rest after lots of digging and sieving

Exciting fossil finds

We have been excavating in one large cave for about a week, and got down to about 1 metre depth. We are sieving the sediment and picking out all of the bones, big and small. Julian is very pleased that we have found some bones of the solitaire (probably all from the same female), rail, owl, night heron, parakeet, petrel, starling and other passerines. As usual, there is lots of small reptile, including the world’s largest ever gecko, which was half a metre long, not including the tail.

At some point I went to explore the other side of the cave. Having stopped to pick up a solitaire wing bone (as you do), I looked up and saw the carapace (upper shell) of a tortoise wedged under rocks and partly buried in sediment. We carefully freed the fragile carapace, which was in pieces, and transported it back to the museum in a big washing-up bowl lined with bubble wrap, where I carefully cleaned, repaired and mounted it. Today we made a space for it in a display case. This carapace might be the third species of extinct giant tortoise of Rodrigues- we are still pondering this, and will send photos to an expert on the fossil tortoises of the Mascarene Islands.

The carapace (upper shell) of a tortoise, found wedged under rocks

As if this wasn’t enough, today (1 May) we visited three caves, to take GPS readings and photos. In the last one of these caves, I spotted another tortoise carapace, in a really awkward position under rocks. As it was nearly 3pm on Labour Day, and we hadn’t brought our washing-up bowl (!), we decided to leave this one until morning. This is why we are celebrating with a well-earned beer! In your face, Jenner and Slater, you should’ve gone to Specsavers!

Braving tight spaces in search of fossils