But many economists say a lasting price collapse is unlikely because the emerging middle class and growing populations in developing economies will continue to have strong appetites for fuels and metals.

Some say that the other commodity bull markets in modern history  approximately spanning 1906 to 1923, 1933 to 1955 and 1968 to 1982  lasted more than twice as long as the current run. They included some sharp corrections before they ran their course, suggesting that the current drop, however precipitous, could be temporary.

Though the picture is slightly different for every commodity, prices generally hit a low point for the decade soon after the terrorist attacks of Sept. 11, 2001, then rose as the global economy strengthened in the following years. From late 2001 until mid-2008, the price of oil rose 800 percent, copper rose 700 percent and wheat rose 400 percent.

The decline of recent weeks has taken virtually every major commodity more than halfway back to its late 2001 price, adjusted for inflation. The recent drop has been so rapid that if the pace continued, it would take only a few more weeks to erase the gains of the bull market entirely.

That suggests to some analysts that prices could hit a floor fairly soon. “The underlying fundamentals of strong demand for energy, food and industrial commodities will come back,” said Michael Lewis, global head of commodities research for Deutsche Bank.

Many analysts think oil could fall to $70 a barrel in the next few months, if not sooner. But it is hard for them to believe it will go much lower: oil is not becoming easier to find, as fields in Mexico peter out and suppliers like Iran, Nigeria and Venezuela remain unreliable.

The costs of finding oil in deep waters or mining oil sands in Canada remain high, in the $60 to $70 a barrel range  and since those are now vital sources of supply, they could help put a floor under the oil price. Additionally, the Organization of the Petroleum Exporting Countries could cut production to try to shore up prices, probably at an emergency meeting it will hold Nov. 18. Analysts note that the credit crisis and economic slowdown will inevitably stall new industrial projects, reducing demand for metals. But the falling prices will also discourage new mining and drilling. When economic growth resumes, that could produce metal shortages that would drive prices back up.