Just over the ridge to the west, Writing Rock bears unusual script-like engravings that have prompted long debate. Geologists have attributed the markings either to running water etching the stone or to ancient glaciers grinding striations into the rock, while others have argued that prehistoric peoples living here some 5,000 to 9,000 years ago made them and that the figures may depict animals and human forms tied to fertility rituals and vision quests. The origin of the “script” remains uncertain, but Sisseton Sioux legends offered explanations for the cryptic markings, including one in which a water spirit emerged from the Sheyenne River at night to write messages on the rock for the Dakota tribes; a girl who saw the spirit would gain many desirable admirers, while a man would become a skilled hunter and warrior or a leader, and each following night the spirits erased the old message and wrote another until they no longer returned after white settlers arrived. In 1890, Theodore H. Lewis of the Northwest Archaeological Survey examined the large light-colored granite boulder known as Writing Rock and published notes and drawings in 1891, while present-day archaeologists support the view that the markings resulted from natural forces rather than human hands.