Geologist Mark Jirsa, describes the geological significance of the Sioux quartzite ridge of southwestern Minnesota. The Jeffers Petroglyphs historic site is arguably one the most significant historic and cultural sites of its kind in the world. Its continued use over 9,000 years attests to its importance in traditional indigenous culture. The Jeffers Petroglyphs podcasts presents a variety of perspectives personal, archaeological, traditional, biological, and geological -- in the voices of those who know the site well.