Environmental Chemistry Field Trip – Day 1, Part 3

There were two more stops on the first day of the field trip. After Appolinaris Spring, we stopped off at the “Sheepeater Cliffs”, named after the local natives’ use of mountain-goats for food. I did get a picture of the small cliff, but who cares. You’ve seen one columnar basalt formation, you’ve seen them all, right?

Oh, well, in case you haven’t seen even one yet, here’s one:

It’s actually kind of interesting – despite the fact that Yellowstone is essentially one gigantic crater left by a volcano explosion, lava doesn’t seem to be a common feature at all. The reason seems to be that the volcanic explosion was an explosion of steam, not melted rocks. Put simply, water seeps down into the ground and gets trapped on top of magma, which is naturally extremely hot. The water can’t boil away as steam, though, because it’s trapped under all that rock, which keeps the pressure high enough that it stays liquid even when it’s superheated. Then, one day (about 600,000 years ago, if I remember correctly) somewhere a crack opened up enough to start letting the water flow out. When it got out from under all the rocks, the reduction of pressure let the superhot water suddenly explode into a cloud of steam. As the water shot out as steam, it let off some of the pressure on the water still trapped underground, which could then also explode into steam….and the whole area got flung into the air on the exploding, superhot steam. Kind of like the way a perfectly innocent looking bottle of heavily carbonated beverage can suddenly erupt in a spray of bubbles if you open it too suddenly.

Or at least, that’s my I’m-not-a-Geologist understanding of the process. The point is, melted rocks aren’t really a big part of the park area’s surface, so it’s interesting to see the basalt cliffs here. The giant hexagonal columns are actually huge crystals of that formed as the melted rock solidified.

This was just a brief stop, though. We piled back into the field-trip vehicles and headed for the Mammoth area of the park. I was originally going to cram that stop into this post, too, but I’m still editing it down to make it less pedantic. Unless my Vast Horde of Loyal Readers would LIKE pedantic…

Incidentally, the College Blogging Scholarship submissions are done as of midnight tonight. Or midnight tomorrow morning, depending on whether you think of midnight as the end or beginning of a day. Finalists get announced on Monday. Here’s hoping I’ll be one of them. That also means that if anyone has any suggestions or comments about how I’m running the blog, the topics I’m picking, and so on, now would be a good time to speak up…

Meanwhile, a couple more posts on the field trip coming up (possibly another one later today) and then I’ll move on to other topics.