Archaic Glen Canyon Style 5 (Glen Canyon Linear Style) and Basketmaker San Juan Anthropomorphic Style images accompany Yucca Blooms and Atlatls on the cliffs at the confluence of Butler Wash and the San Juan River. An atlatl is a tool used by early American Indians to hurl a spear with increased force and accuracy.  It is a finished shaft of wood, about 2 feet long, with a cusp or wood spur at the back to support the spear and a finger holder of leather, wood, or fiber to hurl the spear. In rock art atlatls are depicted by a thin line with a circle surrounding one end of the line. The presence of an atlatl indicates a Basketmaker II culture.