The Main Street fountain, a landmark of downtown Nantucket, was destroyed late Sunday night by a pickup truck that smashed into it at high speed and fled the scene. The incident occurred just after 10:30 p.m. when a white Chevy Silverado struck the fountain head-on, leaving the heavy steel structure in pieces on the cobblestones. Some parts of the fountain were strewn nearly to The Hub and the intersection with Federal Street, nearly 30 yards away. The driver of the truck fled the area, and Nant