This project studies subsurface ice in the McMurdo Dry Valleys of Antarctica, modeling their origin based on field, laboratory, and theoretical work. These ices are highly unusual in that given the shallow occurrence and hyperarid conditions they should have sublimed away, but appear to have existed for many millions of years. The ices are important in that they may provide unique paleoclimate information, insight into the physical behavior of soils in these extreme environments, and provide an analogue for primary Martian processes. The broader impacts are undergraduate and graduate student education. The results may also contribute to understanding recent global climate change.