But how much is "a lot," really? It isn't just a factor of time, but of time under the correct conditions (which are rare). If the right conditions are not there 99.9% of the time, a billion years is shrunk to an effective million years, and probably less than that. It appears that for large stretches of time much of the earth has been under hostile conditions for large scale decomposition under great pressures. What percentage of the earth today (which is mature and therefore "ideal") exhibits these conditions? Not many acres.
The whole plosive "Billions and Billions," uttered in reverential and sacred tones, needs to be de-mystified. We should not be so quickly, almost religiously, enamored by "the Big Number." To put it in a little perspective, if the groundskeeper can't coax a billion blades of grass to show up on the White House lawn this year, it's going to look like real crap.
I’ve got a billion weeds in mine...............I know. I’ve pulled them all at least once...........
FWIW, I have less than no idea what I’m talking about :)
From what I’ve read, I understand that at one time there was actually very little oxygen roaming around the atmosphere, it was mostly CO2. As the plants got their foothold, the oxygen was freed, (kind of all at once, relatively speaking) to the extent that all of the iron in the oceans oxidized at once (relatively) giving us that band of red rock that can be found all over the earth. You can see it in Eastern Pennsylvania, where the very old mountains are showing us their roots. That had to be A LOT of plants to release that much oxygen.
And the conditions don’t have to be perfect all over the earth. Those perfect conditions move around the earth as the climate changes (and I don’t mean that in the evil climate change way!!).
To grab hold of these time periods, think about the Rocky Mountains, which are young, they were born 80-55 million years ago. The earth is 4.6 billion years old. (It helps me to refer to a billion as 1000 million....so the earth is 4600 million years old, and the rockies only 55 million.) (So I get really irritated at global warming people, ‘cause I want to know what the heck melted the glaciers 12 THOUSAND years ago.)
I’m babbling, I know I’m babbling. Just remember that the rain forests are happily decomposing, and an awful lot of the coal came from shallow seas filled with seaweed.
Oh, this is not to say I don’t believe that the earth could be cranking out oil all by itself. Enough pressure, and I’m guessing you could rearrange those carbon chains any darned way you want to!
Your mileage may vary! I do love this stuff, though!