It's taken a while for me to get back into the swing of things after my return to London, but at long last here's what happened on the last few, hectic days in Mexico, which included one last day in the field to collect our final samples:

A 05:00 start was a harsh way to take on the most challenging climb of the trip but by then Chiara and Dave were ready. Although as they trooped out to the jeep, heavy limbed, it was hard to discern that they knew it. Your devoted reporter remained on the bench in Amecameca on the basis of a four-only-in-the-jeep rule; jealous of the landscapes the rest of Team Popo would see and the last chance at such physical endeavour.

I wanted to leave town exhausted but I'd just have to leave educated and elated instead. On writing and curation duties, I was to source rock-packing materials, a somewhat vital task, so was spurred on in the role. In preparation, I demolished huevos rancheros and set off with the sun on my face, a less than ideal command of the language and immense purpose.

Forget what you know about eating fried eggs, tortillas, cream and green chilli sauce at different times.

When riding other animals, it's customary to do it contraflow to heavy traffic. 

My insight into the last day of scientific field work on Popo came as the team arrived back at base early in the evening. They looked at the peak of their exhaustion. We dined quietly but when asked how the day went, Dave gave a dazzling smile and explained how in his element he was. 'Where did your energy come from?' I asked. 'I don't know, he replied. It was some kind of euphoria. I just kept on going, following my body rhythms.'

Reaching their highest altitude yet of 4,474m, Chiara too had a strong final day in the field. She described how for her, Hugo had set the pace and by 'making small footsteps in his wake', she could maintain the energy to make it. 'Without Hugo, I would have failed,' she said, with what's become her trademark grin and shrug of the shoulders. 

Hugo: Two steps ahead and a dab hand with a 5kg mallet. He's a field work essential.

Popo: Quietly cultivating a 50-a-day smoking habit.

Beautiful Monarchs converge on an outcrop.

I'll name that layer in one.

Chiara's research will very much depend on the data she generates once she's tested these samples back at the Museum. However, as the week progressed it's clear Dave can already see how his work here will enhance the Museum's collections. The Popo samples from this trip will have context of the type he rarely sees in the collection, with his photographs and field sketches giving an exact visual of the make-up of each outcrop.

This, along with the GPS and field notes places the sample more firmly at it's location and - to fully understand Popo - this helps immensely. 'It was also great to get back into making sketches,' he says. 'To be here to collect from the source is invaluable. I have much more to information to offer those wanting to use these collections now.'

Dave tells me his drawings have been 'enhanced' by years of doodling with his two kids.

Local dining requires rapid response paperware.... In truth, our visit to procure more packaging for the specimens.

Amecameca prepares for a two week festival as we depart (a coincidence?)

I don't know what he's selling but I want one.

Lost Highway: Laden with rocks, Dave and Chiara's taxi takes ten wrong turns too many. Mostly to the right.

If any of you have seen the film, The Canonball Run, you will have some insight into the way Mexican highways and byways work. As Chiara and Dave's taxi heads for Mexico City and the beginning of our journey home, we spot a car boot full of people with their legs sticking out, the vehicle swerving between traffic. My palms begin to sweat at the sight.

The 90 minute journey extends to a joyful five hours as the taxi gets lost and our Sat Nav diverts us to the more 'exhilarating' - i.e. terrifying - parts of town. A lifetime later, we've booked into our hotel and hit the streets of the busiest city I've ever been to and spend the evening re-living the highs and lows of the trip. The sheer volume of people traffic serves only to remind us of the dangers of Popo, a mere 70 kilometres away. It also makes me think of how vital Chiara's research could one day be in predicting their safety.

Before I tell you about another dramatic day in the field, here's a choice clip of our base town Amecameca. Lest we forget just how interconnected Popocatepetl volcano and this cool little town's residents are.

(This video has no sound)

Today we travel to a station in Tlamacas, 4,000m up, and on the way the subject is raised of Thursday and Friday's 5,000m climbs. 'What do we do if someone fails?' says Chiara. Hugo discusses the severity of symptoms and probability of sickness increasing with numbers. I suddenly feel the opportunity to climb slipping away. But altitude sickness is not something you can take sole responsibility for. If you get sick, the whole team is affected. So it's clear who should stay and who should go.

For now though, we travel together and hit the point in the road where a deep volcanic ash becomes our path forwards. 'We can drive a little further, then we walk' says Hugo. With that, our four wheel drive tries to engage it's four wheels. On our right is a drop of say 20 metres. Our back right wheel decides the latter is the route this car is taking and Hugo's passengers lose all colour in their cheeks. I bail without hesitation and we all attempt to push the car to safety, walking boots slipping ever nearer toward the drop. Purchase achieved, our lungs recover and our nerves unjangle.

Getting stuck is the pastime of a true geologist.

Where are we? It's a landscape I've never seen before, never thought existed. 'We're on the moon,' says Dave grinning.

Ash, more high altitude Sacaton and mounds of alien-looking mosses. A perfect location for a 70's Bowie video.

The conversation stays dark like the volcanic ash we tread as Dave shows me how to grip a walking pole so as not to break my wrists if I fall. I appreciate the technique and continue the hike to the station. My heart is racing but my pace is slow. Hey altitude, nice of you to drop by again.

Chiara steams ahead on a full recovery. Last one up writes the blog.

We're on the south west side of Popo and as we reach 4,000m Hugo needs to inform Cenapred (National Centre for the Prevention of Disasters) of our wish to collect samples. The monitoring equipment they use will pick up our hammering and - possibly - even our footsteps. Negotiations take place and we continue.

Hugo points out an incredible face of bi-colour lava. 'Look at the layers, says Dave. 'Shows incredible flow.' Hugo, armed with hammer smashes clean samples for everyone. 'It's between 1,300 to 2,000 years old. Two generations of magma, perhaps. 'The excitement is palpable, our dark thoughts are shifted.

Undeniably beautiful but I wouldn't want to carry a slab at 4,000m.

On our ascent to the station we see some fabulous scoria. One of the major igneous rocks, lightweight and extrusive. I'm sure I see Dave skip. And there were definitely three 'awesomes' as he surveyed the rocks. But we'd not collected any as the ascent seemed our goal. We want some now, especially a large specimen we'd all cooed over.

To get it we need to descend and it's steep, loose and a little scary to Chiara and I. 'As we Italians say, 'If you don't have head, you give leg!' she says which means we have to go back and get it. 'It's FINE. Let's do a scree run,' says Dave nonchalantly. I check my walking pole straps to ensure non-breakage of wrists and we run down the slope after Dave who, arms outsretched and invigorated is shouting, 'Easy!' 

Altitude-enhanced snack packaging. Never gets old.

I've brought with me a friend's backpack that she took to Everest. Its roomy to say the least. I offer it up for the collection of the big scoria. Proudly I carry what Dave and Chiara were sure would make it into the Museum's collections or possibly a gallery. Ten glorious minutes of hefting it, then I beg Dave to carry it.

Before we head back to the jeep, we survey Friday's climb. The ten hour hike. We've fared very well today, quite elated stomping down from the station. Not even tamales can prepare the team for what's to come.

"It's so close, let's do it now," says Chiara.

My post for today shall begin with a clip of what we've been priviledged to see every day whilst on field work in Mexico. Lee, Dave and I are all keen photographers and agree that there's a picture wherever you look. The light is literally perfect and there's barely a sound (bar that of scientists chipping rock) that can be heard in these wide expanses of grass, pines and volcanic matter.

(Note: this video has no sound)

After a high buzz start to the day, linking live to our Attenborough Studio to take excellent questions from sweet, keen students in a special event for schools, we visit our next outcrop (an area of exposed rock), a beautiful area called Tlamacas at 3,900m above sea level. No sooner had we piled out of the jeep than we see the cheery sight of Hugo, springing up like a mountain goat, to rocks roughly 10 metres high. I ask him as he descends a little later what is the highest he's climbed. 'K2', he beamed, 'at 7,300m.' I feel my lungs tighten and my admiration grow.

Hugo and Chiara investigate. Popo watches on in the distance.

I approach Dave to nosey into his activities by the exposed rock face. What have we here then? 'Volcanic rock. Feldspar. The likes we've seen here already. It's called Dacite.' I look on as he photographs the rock and ask how these images are then used. 'Pictures go alongside the collections. They show the features of the flow.' This has a snappy ring to it but a lot of sense too. Unfortunately Dave does not receive the same kind of imagery with samples given by others to the collection. 'If only' he smiles. 

I'm keen to know what finding similar rocks means in different outcrops. 'It's unusual not to have lots of change in a volcano but Popo's rocks so far are fairly similar. Chemistry should change over so many hundreds of thousands of years but they've not done so much here. The whole process is a bit random, so change should occur. This makes Popo pretty interesting.' The team chip away samples and discuss their finds. Hugo and Chiara pass samples between each other until Chiara pleads with hands full. 'Poor Italians, you only have two hands' laughs Hugo.

Chiara takes five to speak with Hugo's University TV Crew.

Our second outcrop is but a walk away. A steep walk. Downwards. Chiara must have some idea of how steep and she looks apprehensive. Her apprehension makes me excited. Are we going on a difficult hike? Hugo takes us to a spot, points down and says he'll meet us at the bottom. 'Don't follow the river for long as there are cascades. I'll meet you down there.' Our springy mountain goat not coming? Then I'm with Chiara on this one.

Cascades you say? Dave and Chiara following the river. And by river they mean where it used to be. I was looking for water. Doh.

I discover the senses figure highly in rock collecting. Firstly, as I sniff a fresh surface of exposed rock I discover that licking them is an everyday geologist pastime. Why? 'To taste the minerals' says Chiara, which seems a reasonable enough idea. Soon after I see Dave shaking his head in disapproval as he hammers a rock face in several places. 'No, no, no' he says as he slings the 'bad' rocks to one side. What gives, Dave? Well, sound is important too it seems. 'The thing you want is kind of a tinny sound when you hit it. Means its hard, unweathered and fairly fresh.'

You go first. No, you go first.

Our search for a particular rock named ignimbrite reaps little rewards. An incredibly weathered outcrop is what we discover and this is impossible to sample usefully. We have, however, tested our fitness by climbing down pretty much a vertical slope, zig-zagging all the way. Thank heavens the high altitude grasses or Sacaton are strong rooted or this reporter would be no longer with you. We stop, eat chocolate and ponder our route to meet up with Hugo.

Our first evidence of large mammals as we hike our way to meet Hugo.

The compass looks right, the road looks semi-alright (in two places we duck under barbed wire to continue) and we feel confident of our direction to the jeep. An hour passes and Chiara seems slower and more laboured. We check on her health and she admits to feeling the altitude as she takes out her inhaler and calms her asthma. Dave and I have headaches. Unusual and intense.

We continue more slowly and Chiara hangs back to throw up in the most polite way I have ever seen. There's no doubt it's moderate altitude sickness. A few more stops and Hugo hoves into view. Exhausted glee. It's back to base and straight to bed after a long day in the field.

In just over a week we fly out to Mexico to prepare for the arrival of Museum scientists Chiara Petrone and Dave Smith. We will be following them as they ascend the 2nd highest volcano in North America and the most active in Mexico, Popocatepetl.

Familiar with field work on active volcanoes such as Stromboli (Italy), Santorini (Greece), Vesuvius (Italy) and the Mexican Volcanic Arc, this is new territory for Chiara, whose aim is to collect samples to bring back to the Museum to study.

In early February, we'll be following Museum scientists as they perform their field work on Popocatepetl - the 2nd highest volcano in North America and the most active in Mexico. Image: Cvmontuy

Working alongside our scientists is Professor Hugo Delgado-Granados, a researcher from the National Autonomous University of Mexico (UNAM). The team are hoping to discover the entire history of the volcano from the rocks they collect, spending a working week hammering in the outcrops and climbing up to 5,000 metres, carrying rocks on their backs.

Reaching only a few hundred metres from it's very peak, the crater area is at present, too dangerous to climb to as 'Popo' is in an 'eruptive mood'. Let's hope this mood stays stable enough for us to climb and find specimens that will help them fully understand this incredible, natural phenomena.

Join the adventure and post up questions for the team on our blog posts, and come along to the Museum's Attenborough Studio where we'll live-video-link on the 5, 6 and 9 of Feb. Altenratively, kick back and watch us on a live-web-stream here. Whatever you do, do take part. We'd love the company as we scramble up a constantly erupting volcano with backpacks full of black rock.