- Jesse Allen, Earth Observatory
- Most spring floods are triggered by rain or melting snow, but when the Skafta River of southern Iceland flooded in late April 2006, geologic activity may have been the driver. The river flows out from under the Vatnajokull Ice Cap, a large permanent field of snow and ice that covers more than 8,000 square kilometers of southeastern Iceland, including a number of volcanoes and other regions of geothermal activity. Over these hotspots, the lower layer of the ice cap melts to form glacier lakes, some of which drain into the Atlantic Ocean through rivers such as the Skafta. Other lakes are dammed by walls of ice from the overlying glacier. Catastrophic floods can occur when water breaks through the ice dams and bursts into the rivers, or when geologic activity increases and melts more water.
- Pierce County — Thumbnail History (historylink.org)
Pierce County, located in southwestern Washington abutting Puget Sound, encompasses an extremely wide range of elevations: from sea level on Puget Sound to 14,410 at the summit of Mount Rainier. The entire footprint of Mount Rainier, an active Cascade volcano encased in more than 35 square miles of snow and glacial ice, lies within the county’s boundaries. Pierce County comprises 1,675 square miles, placing it 23rd in size among Washington’s 39 counties…
