And so it is with geology. Without perspective we have no idea what we are dealing with. Geological time isn’t like the time you and me know. It’s all crazy and mixed up and stuff. To geology, an hour isn’t really any time at all. Nor is two hours. Or three hours. Hours are out. While we are at it, let’s throw out days, weeks, months and years. It takes a long time to turn a living trilobite into the stony novelty that we know today. To begin to get some perspective of what we are dealing with, I will give you a map of geological history...
What that tells us is that geology is vast. Well, the earth’s timeline is vast anyway. Way vasterer than we can imagine. What’s that? You say that you can handle it? You think you are tough enough to deal with the madness I’m about to spew out at you like an epileptic spitting cobra? Very well, try this on for size Junior. The earth is 4.5 billion years old. That’s right. Billion. That’s 4,500,000,000 years. If you are lucky, you will live to be 80 years (or more if you’re female!). That means the earth is only 4,499,999,920 years older than you. You and I are insignificant when you have the right perspective.
PRECAMBRIAN – (4.5 billion to 570 million years ago)
To start out with, the Earth wasn’t a very friendly place. We would hardly recognize it. Instead of beautiful oceans and Costcos, all you would see is a violent ball of molten rock being bombarded by space debris and ice and stuff. And you can forget about breathing. There was no oxygen, or at least not enough for you to work with. The best visual I can think of is as if you were inside a space-themed casino.
Then, approximately 4.45 billion years ago, space got serious. Out of the eternal darkness came a mars-sized planet that smacked right into the side of our molten casino. Debris flew everywhere, kittens were upset, and I’m betting things were down-right noisy for a while. Anyway, some of that debris flew out into space and became our moon. So remember when you see the moon you are looking at some pretty pissed off rock that wants nothing more than to smash back into us and get back where it belongs. When all was said and done, it was this collision that gave us our current planetary tilt and rotational speed. Maybe.
And so things went. By 4.4 billion years ago, the heavy metals like iron and nickel settled near the center of the planet (cus they are heavy) and the lighter elements like silica, carbon, and the rest made for the surface. Water arrived via comets, which seems like a really neat way to get water. After a while, space worked out its issues and started to lighten up on the planet and its new little moon. An atmosphere began to show up, but instead of oxygen it had a bunch of other wierd stuff. Again, like a casino.
Here's a picture of what some people think this may have looked like....
It looks like the Earth was probably a lot more steamy than it is now. Than something weird happened. 3.2 billion years ago some of the stuff came to life. It wasn’t much, just a colorful little alga-like things and the Irish. Nobody knows why. Maybe you should ask your religious leader or baring that, read a bumper sticker.
As is probably not a surprise, no one really know what the planet looked like after the oceans formed and the earth stopped being pelted by space junk. All we have to work with are old rocks that have been cooked, crushed, melted and buried. What we know is that as of 3 billion years ago there were continents and they were in some sort of shape. Little creatures in the ocean figured out how to make photosynthisis happen, and this combined with volcanos lead to the sudden influx of oxygen. This is fortuitous for us, as we require oxygen to live.
We should also be glad that life is hardy, because things were about get rough for our little alga friends. Starting 2.2 billion years ago the earth kept freezing into a little ice ball like a freezer with a sticky thermostat. Everything was covered in ice. You, me, everyone else, covered in ice. Life persisted, but it probably wasn't all that it was cracked up to be. In utah, there is evidence of this icy goodness in a formation called the Mineral Fork Tillite. This formation appears to be remains of rocks and debris scraped up by glaciers as they wandered by. It's believed that volcanic activity was responsible for breaking up the the glaciers and giving us the much needed greenhouse gasses that warmed us up. Anyway, this happened several times. Maybe.
Near the end of the Precambrian, things kinda settled down and life started to take off. All sorts of stuff happened, but we don't really know a lot of it. Which is too bad because the Precambrian time accounts for 87% of the earthy history. That's like only seeing the last 3.9 minutes of a half-hour sitcom and trying to figure out what just happened. Somehow people have decided that as the Precambrian closed, most of the continents were located somewhat near the equator. Or possibly near the south pole. Somewhere in that area. Utah may have possibly looked like this maybe perhaps....
Multicellular life (fancy alga) showed up about 600 million years ago, and quickly put the simpler lifeforms in their place, and as of 570 million years ago, some of these multicellular organisms started to look really wierd. But that's no longer any of the Precambrian's concern as the sun had set on this period of earth's history.
SCOTT'S GEOLOGICAL RATING OF THE PRECAMBRIAN