the theory of early earth colliding with a mars-sized object is widely accepted in the scientific community. velikovsky's work is another matter. but to be fair to him, the problem isn't that much of his work was wrong. the problem is that the scientific establishment tried to censor and suppress his work. if he's wrong (which he often was) eventually free scientific inquiry will discredit him, but to muzzle him establishes a dangerous precedent going back to the days of galileo being forced to recant by the church. velikovsky's books may be out of print, but if you really want to find them, there are plenty of used copies available on amazon for $20-30.

but a point that was made in the history channel show is that the mineral wealth in the sudberry mining region was created by an asteroid impact. although the asteroid didn't bring the copper or nickel, it blasted a hole 18 miles deep, and allowed the molten copper and nickel below to come to the surface.

the show also mentioned a scientist who reasoned that a huge crater in arizona had been caused by a meteor. he found trace amounts of iron, and calculated the size and volume of the object. this was almost a century ago, and even at the price of iron back then, he thought he was going to become rich. so he raised and spent $600,000 ($10 million in today's dollars) and drilled a bunch of dry holes with only trace amounts of iron at depth.

he was right about the crater being caused by an impact, but the iron was long gone. with today's modern technology they displayed computer graphics that showed the shock wave from the impact almost completely vaporized the iron. so these impacts from space don't bring anything of economic value; they just expose whatever the earth has to offer, whether it is gold in south africa or oil in the gulf of mexico. still, these impact craters are a good place to start, and mining companies are using satellite imagery to look for them.