This is the title of a very interesting article that probably answers one of the questions about which you have wondered.
As discussed on the AIG website,
"Some people have wondered how the vegetation during Noah’s day could produce so much coal, since today’s vegetation would produce only 3% of known coal reserves.
"To find the answer, we must reexamine the assumptions behind that estimate.
"First, it is often assumed that around 10 feet of peat is necessary to produce 1 foot of coal. But if you consider the weight of peat and coal, or if you consider the energy content, then 10 feet of vegetation probably produced 5–10 feet of coal.
"Second, it is mistakenly assumed that the world of Noah’s day was much like today. That is not the case. It turns out that Noah’s world was very lush, producing nearly six times more vegetation than we see today."
It is very likely that "lush vegetation might have covered up to 75% of the pre-Flood world. "
For more details, you will want to read a brief excellent eye-opening article written by Dr. Andrew Snelling (PhD in Geology).
Don't panic -- even though the article is written by a Geologist, you WILL be able to understand it.
So with that by way of introduction
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