Experts agree that the earth will eventually run out of certain low-cost, nonrenewable resources, possibly as early as a century from now. Will the transition to reliance on other, more abundant resources be smooth or discontinuous? Might industrial societies experience a marked decline in living standards--a radically different kind of society from the one we now know? Geologists maintain that once inexpensive high-grade resources are exhausted, economic growth will slow. Economists are more optimistic: they believe that new technologies and materials will be substituted rapidly enough to prevent major economic dislocations.