   "It's a cautionary tale," Burns told journalists gathered
here for TV's summer press tour. "It's an epic of human pain and
suffering, but also the story of heroic perseverance."  "The
Dust Bowl" chronicles the environmental catastrophe that,
throughout the 1930s, destroyed the farmlands of the Great
Plains, turned prairies into deserts and unleashed a series of
massive and deadly dust storms -- so-called black blizzards --
upon the region.  It was "an apocalypse that is so hard to
fathom and comprehend," Burns said.  Burns and fellow filmmaker
Dayton Duncan said they had been considering a documentary on
the Dust Bowl for years and finally dove into the project,
sensing an urgency to work on it before aging survivors passed
away.  One of the survivors featured in the film is Cal Crabill,
who lived in Colorado during the Dust Bowl until his family fled
to Southern California. He grew up in Burbank and later attended
UC Berkeley. Crabill recalled being out on his horse as an
8-year-old when a huge dust storm