A soft rock called sandstone began moving under this pressure.

VOA: special.2009.04.15

Sandstone is a soft rock.

VOA: special.2009.07.20

The area is popular for school field trips because students can hunt for fossils in the soft sandstone cliffs, said Michael Rutzick, who was at the park Wednesday and lives in nearby Mendota Heights.

NPR: 1 Child Dead, 1 Missing In Minn. Park Landslide