Betula Lake, Manitoba, is a freshwater lake and resort area in Whiteshell Provincial Park, 145 km by road northeast of Winnipeg. Opened to cottage development in the 1950s, Betula is a popular swimming, waterskiing and fishing area. Its cultural history is especially notable, for located in the area are petroforms - boulder mosaics created by prehistoric peoples. These outlines, made of rocks weighing up to several hundred kg, are laid on open granite tablerock. Turtle and snake effigies predominate, but circles, human effigies and geometric patterns have also been found.

The petroforms are thought to stem from the Laurel Culture (500 BC to AD 800). Some may have been used to mark portages, but the more remote sites were likely used for religious ceremonies and rituals. Some alignments correspond to astronomical phenomena. Their creators may have been ancestors of Algonquian-speaking peoples who continued to arrange petroforms after moving west to the High Plains. Systematic study of the Whiteshell mosaics began in the late 1960s.