Accretionary Wedge #5: Geological Misconceptions and Pie
Happy National Pie Day, and welcome to the fifth edition of the Accretionary Wedge, the Internet’s premier blog carnival for the earth sciences! First, I have some news for you. Make sure you’re sitting down before you read this:
- Diamonds are not made from coal –
With either [melt catalyst belt or chemical vapor deposition], nitrogen from organic compounds in the coal would impart a yellow-green color in the diamond due to the absorption of the single N defect.I assume this also holds for the Superman method.
- Axial tilt is the reason for the season.
- Santa Claus is, at best, a metaphor.
- Dinosaurs aren’t dead –
In fact there are some rather bewildered-looking avian dinosaurs outside my kitchen window wondering how Bubba the Fat Squirrel managed to steal the fat balls from 1.5m high up on our dispenser.
- Earth’s mantle isn’t molten. No, really, it isn’t. Mantle flow doesn’t drive plate tectonics, either. But the mantle is 3D. In fact, most things are 3D… except, of course, gorgeous illustrations by William Smith.
- Small earthquakes don’t do anything to prevent bigger earthquakes. You see, each magnitude 4 earthquake releases about 30 times as much energy as a magnitude 3… but an odd fact of seismology is that the ratio of M3:M4 earthquakes is constant over time, at about 10:1. This leaves us with a factor of 20 lurking ominously in the shadows.
- California is not going to fall into the sea. No, really, it isn’t.
- The Heisenberg uncertainty principle is neither relevant nor funny at the macro scale.
- Crustal folding doesn’t always mean a thickened crust – though the crust in that counterexample can still be fairly described as “thickening”.
- Lava is not a swimming pool. Oh, and the mantle isn’t liquid.
- The mantle is the most annoyingly least-understood part of this planet.
In other news, Mel discusses a test designed to expose students’ geological misconceptions – and why it might not always work. Saxifraga talks about what glaciers actually do – “The moraine five kilometers in front of the modern glacier margin is not a sad sign of the ice retreat, but a sign of a not climate related natural phenomenon called glacier surge and the retreat from the Little Ice Age moraine is partly an adaptation to warming over the past 100 years.”
In honor of National Pie Day, Callan Bentley shares his favorite baked-goods teaching analogies – but he hasn’t thought of any pielike concepts in geology, maybe you can help? Brian objects to the “layer cake” analogy, suggesting that perhaps we should use lentils instead. Lentils? I guess I’ve seen recipes for lentil shepherd’s pie…
Finally, Lab Lemming has a delicious rocky planet pie chart, and by “delicious” I mean “my dentist told me only to eat gas giant pie charts”.