Contact: Sandra Hines
University of Washington
Caption: University of Washington researchers collect samples from Gran Barranca, Argentina, that offers access to layers of soils, plant remains, volcanic ash and sand going back millions of years. The section pictured represents 800,000 years of layering and is mainly composed of volcanic ash deposited by wind and rivers.
Credit: R. Madden/U of Chicago
Usage Restrictions: Credit required
Related news release: 'True grit' erodes assumptions about evolution