Wikisimpsons - The Simpsons Wiki
Mount Springfield, also known as the Springfield Volcano, is a long-dormant volcano located just outside of Springfield. It once caught fire from a discarded camera light bulb. Bart and Lisa were on the mountain earlier to take a picture for the Springfield Phone Book cover contest; Bart as a prank shot the light bulb at Lisa. The fire spread, trapping Bart and Lisa on the mountain, until Barney and a very inebriated Homer (Homer downed six cans of beer to ensure Barney remained sober to pilot the helicopter) lifted them to safety.
A mailman was once discovered frozen in Mt. Springfield's snowcap.