[putupjob]

Let's see... 2 million blocks in 20 years.
Working 12 hour days that means
2,000,000 / 20 / 365 / 12 = 22 blocks/ hour
1 every 3 minutes for 12 hour work days for 20 years.
And some of these are 70 tons.

Hmm... I'm not sure if the Michigan story is the whole story.

[SoCal Pubbie]

Herodotus wrote that it would took 30 years and 100,000 slaves to have built the great Pyramid of Cheops. There are 2,300,000 blocks of stone with an average weight of 2.5 tons each in the structure. Assuming that they worked five months per year when the Nile was flooded (although that may have been only to move the blocks), that would be 76,666 per year, or 15,333 per month. Using a thirty day month that's 511 per day. Working twelve hours per day, that is about 43 per hour. If you divide 100,000 into 200 man teams, there would be 500 teams, so each team would have move about one block per day.

Whatever the actual numbers, it's no mystery.

[Ichneumon]

And some of these are 70 tons. Hmm... I'm not sure if the Michigan story is the whole story.

Well, the technique can be scaled up by just increasing the number of workers:

This is a relief from the tomb of Djehutihotep. Note that a) there are a crapload of workers depicted, and b) there's a guy at the front of the statue pouring some sort of liquid in front of it, perhaps water or oil, to allow the statue to slide more easily.