When: Tuesdays-Thursdays. Continues through April 25 2013
Events are guided by volunteer naturalists. Geological events and formations of the canyon are discussed on a Gneiss (geology) walk, from 8:30 to 11:30 a.m., Thursday, April 25. Activities are led by volunteer naturalists; free with $5 daily or $20 annual admission to the park. Call or visit scvntucson.org for more information.