Spread the load of the jack over a wide area with a large block of wood. It's the same concept that keeps a bulldozer that weighs thousands of pounds from sinking out of sight on a muddy construction site.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!