Originally posted by: Jeff7
Oh not this again.
EARTH IS FLAT TOOOO OMG TEH NOES!!!!
Oh, and it's turtles all the way down.
Originally posted by: Perry404
I have to say I think it's obvious land is moving or there would be no mountains.
Plate tectonics. Educate thyself on it. You've got a big crispy shell covering a gooey cream filling, under all kinds of pressure. Ever heard what happens when you microwave a jawbreaker? Some layers liquefy, while others don't. Pressure builds, and things can crack, with considerable force.
While Earth isn't about to blow up, that pressure does keep the crust fractured, and since the pieces are floating atop a big sea of pressurized goop, there's going to be a little bit of jostling around. Sometimes things bump into each other. We tiny humans think this gentle bumping can be insanely destructive, as it causes the ground to shake a few feet this way and that, or it causes little ripples throughout the ocean, but we call them "huge" because they're several times our tiny height.
Or sometimes one of these plates gets squished underneath another one, and as it stays down there, it heats up and melts. Pressure builds from the other side, and forces even more of the plate down into the mantle - a subduction zone.
Volcanoes - pressure builds, and sometimes it finds a way out. We think of them as huge eruptions, but really, a lava flow to Earth is just a little bit of juice squirting through the surface, no big deal. You might pop a pimple and think nothing of it, but you've just disrupted the lives of millions of bacteria, cheerfully enjoying their little home in your face.
One of the points I'm making here with this sort of language is that people seem to have trouble grasping the size of Earth, relative to one person. As such, they have a tough time understanding how some of the larger scale processes work. They're used to working in terms of small things, like cars, or buildings. Tell them about plates that cover millions of square miles, and the process in their mind goes, "Big? Really big.....buffer overrun......rabbits are fuzzy....invalid theory." You get an error message and try to figure out some other reason.
Big plates doing all kinds of complex interactions, earthquakes, volcanoes, tectonic theory, pressure, heat......bleh. "Earth is getting bigger." That's nice and easy. I understand how things get bigger, like inflating a balloon. Easy. I can understand it so it must be right.
Some of these things aren't too tough to understand - if you can change your scale of thinking, move away from the tiny human world, and look on a geological, or astronomical scale.
The only grain of truth, by comparison, is truly a grain - Earth IS growing. Every day, interplanetary dust rains down on us, tons of it every day. Tons. Tens of thousands of kilograms. Earth's mass? Google's answer to that: 5.9742 × 10^24 kilograms. 10^3/10^24 = 0.000000000000000000001
Ain't gonna make a lot of difference. Earth still growing? Nope. The majority of that accretion took place billions of years ago. Leftover chunks that cause occasional impacts are dusty leftovers that haven't been swept up yet.
