Monturaqui Impact Crater (Monday-Wednesday Dec. 8-10)

For the last three days we’ve been on the trail of impactite. We’re a team with a mission – and that mission is to sample as much of this melt rock as possible. We have big plans for these little rocks – statistical analysis of size distribution, geochemical analysis of compositional variation, geochronological analysis of impact crater age. The only problem is that they’re really quite difficult to find, especially when you’re walking around just looking at the ground. The best way to sample (a technique perfected by Nathalie) is to assume the following position: kneel on the ground, preferably facing uphill, and bend over until you are between 18 inches of the ground and your nose hits the dirt. Then, and only then, can you truly observe the abundance of impactite littering the ground. These guys range in size from a few millimeters to almost 10 centimeters – of course the bigger ones are so much easier to find that most of them have already been picked up by previous expeditions and meteorite hunters. We’re quite lucky that Monturaqui is separated from civilization by 2 and one-half hours of some of the bumpiest roads (and I do use the term ‘road’ loosely here) I have been on. Some parts are more accurately described as driving over slightly less large rocks between the boulders. Only truly inspired explorers make it out this far. Because of that, we actually have quite an abundance of impactite, especially the smaller pieces. We’ve been working hard these last few days, and have mapped out and sampled multiple lobes of ejecta. Nathalie has been practicing her zen and thinking like the crater – or would it be the meteorite? – to aid in her mapping of the ejecta. According to Carlos, she also is able to call up a gentle breeze when it gets too hot. Maybe we’ve been getting a little too much sun lately.

I have been quite impressed with Nath’s zen mapping skills, and in an effort to expand my horizons a little, I decided to forgo my usual field approach of rock smashing and give the zen a try. I can’t say I really felt it working for me. David and Sarah and I were walking around the edge of the crater, continuing a survey of a melt lobe the rest of the group had started a few days ago. We found a few impactites, nothing really impressive, and then we hit a patch with nothing. There’s not much more depressing than crawling on your knees over very sharp and pointy rocks, looking for tiny blobs of brown melt rock, for what feels like miles, only to find…nothing. Lots of sharp and pointy rocks, though, and it felt like my knees found every single one of them. Not being the type of people to just give up, we soldiered on, continuing on our quest for impactite, but inside I was having doubts. What if it was restricted to a small area? What if Nathalie and the rest had already found every single piece left on the crater? How could I come back empty-handed? Then, just when it looked over for us, I decided we should try one more traverse along a fairly uninspiring patch of granite scree. We walked, and looked, and bent over, and nothing. We were three well-educated individuals devoting all of our attention to finding some little pieces of brown, bumpy, lumpy, glassy rock. Still nothing. But there – hiding under a larger rock, a brown blob. A melt rock! I had found one, but only a small one. We continued on, hopeful. There was nothing for another few meters (and when you’re crawling, a few meters seems like forever), until suddenly, they all seemed to appear at once – the ground was absolutely covered with impactite. I would see one and reach to grab it but get distracted by a bigger/better/closer piece on the way. Sarah was an impactite picking pro – she had easily twice as much as David and I put together by the time it was time to leave. We have (unofficially) named our find the Byram-Peate-Peate lobe (BP-squared for short). We’ll see how that goes over in the peer-reviewed science articles.


Our success at finding the BP-squared lobe is just a small part of what has been a highly successful field project. Nathalie, Edmond and Carlos have invested a large amount of time and effort to finding, mapping and sampling impactite lobes that haven’t been mentioned in the literature before. We’ve defined new boundaries for these deposits and we have high hopes that the exciting science discoveries will continue with the lab work we have to do on this sample material in the coming year. We finished off a spectacular field day with a Team Iowa photo – Sarah, David and I on the rim of Monturaqui with a University of Iowa flag for scale. Did I hear a ‘Go Hawkeyes!’ somewhere in the breeze?