This article was published in Scientific American’s former blog network and reflects the views of the author, not necessarily those of Scientific American
I've been collecting various geological odds and ends for months. Since Halloween is a time of going around begging for tasty treats, with no knowing what you'll end up with, this seemed like a good time to spill the collection on the floor and pick out some delights. No tricks here; just treats!
Look at this utterly lovely satellite view of the Mackenzie Delta! It's like the Arctic took up watercolors. This is a marvelous illustration of how rivers bring sediments from far afield and deposit them. Some of the most interesting sedimentary rocks I've seen come from ancient deltas. And here, the new delta is made from old sedimentary rocks, many laid down in very different conditions. Earth is a restless planet, ceaselessly remaking itself.
Halloween often involves wizards, so let's have Wizard Island! From space! If you've ever been to or read about Crater Lake in Oregon, you know that Wizard Island is a super example of a cinder cone, surrounded by some of the bluest water on earth. It's nestled in the caldera formed by the catastrophic eruption of Mount Mazama nearly eight thousand years ago. In this satellite image, you get a good sense of the roundness of the lake. This is one of the most beautiful places on Earth. Definitely a special treat!
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Let's continue with the delights from NASA. I can't wait to introduce you to Earth's new moon! For a very long time, we've assumed Earth wasn't like the other planets, who often have many moons. It turns out we've had two moons for about a hundred years now! Our second moon is just a teeny thing compared to our giant Moon, a mere bit of space rock captured by Earth's gravity. But it is a moon and it is ours and we love it. What do you think we should name it?
We move now from outer space to under the sea, where we encounter a very unusual submarine volcano off the coast of Baja, Mexico. We have a wee mid-ocean rift, the Alarcón Rise. It's only about 30 miles long, but it's got all the things a typical rift has got: a ridge, hydrothermal vents, and basalt lava flows. But it has also got something no other mid-ocean ridge without a hotspot has got: rhyolite. If you remember your magmas, you know that rhyolite is about as far from basalt in composition as it's possible to get. This is the only place on Earth that we know of this happening. Tests on the rhyolite reveal that the most simple explanation - that the magma incorporated some high-silica crustal rock - isn't the right one. (Sorry, Occam!) This rhyolite appears to have been cooked up by the ridge itself with a simple increase of volatiles, probably by incorporating a heaping helping of seawater. Exciting!
And finally, happy 7th Anniversary to the Menominee Crack, which is a geologic pop-up that popped up early one morning, startling locals and causing a formally-dressed scientist to investigate without even changing his shoes. Pop-ups are fairly well known, but this one, formed in an aseismic area, is pretty unique.
Enjoy your treats, my darlings. And don't worry. This early taste of our Halloween goodies won't spoil us for the post I have planned for the big day itself!
