At Cafe Hayek, Don Boudreaux quotes economist Julian Simon
“Natural resources are not finite in any meaningful economic sense, mind-boggling though this assertion may be. The stocks of them are not fixed but rather are expanding through human ingenuity.”
Here's a related quote about natural resources from economist Thomas Sowell
in his book "Knowledge and Decisions":
"The cavemen had the same natural resources at their disposal as we have today, and the difference between their standard of living and ours is a difference between the knowledge they could bring to bear on those resources and the knowledge used today."