Glacial erratic boulders of King County are large

glacial erratic A glacial erratic is glacially deposited rock differing from the type of rock native to the area in which it rests. Erratics, which take their name from the Latin word ' ("to wander"), are carried by glacial ice, often over distances of hundred ...

boulders of rock which were moved into

King County King County is located in the U.S. state of Washington. The population was 2,269,675 in the 2020 census, making it the most populous county in Washington, and the 13th-most populous in the United States. The county seat is Seattle, also the st ...

Washington Washington commonly refers to: * Washington (state), United States * Washington, D.C., the capital of the United States ** A metonym for the federal government of the United States ** Washington metropolitan area, the metropolitan area centered on ...

by glacial action during previous

ice age An ice age is a long period of reduction in the temperature of Earth's surface and atmosphere, resulting in the presence or expansion of continental and polar ice sheets and alpine glaciers. Earth's climate alternates between ice ages and gree ...

s. The

Pleistocene ice age The Pleistocene ( , often referred to as the ''Ice age'') is the geological epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was finally confirmed in ...

glaciation of

Puget Sound Puget Sound ( ) is a sound of the Pacific Northwest, an inlet of the Pacific Ocean, and part of the Salish Sea. It is located along the northwestern coast of the U.S. state of Washington. It is a complex estuarine system of interconnected ma ...

created many of the geographical features of the region, including Puget Sound itself, and the erratics are one of the remnants of that age. According to Nick Zentner of Central Washington University Department of Geological Sciences, "Canadian rocks restrewn all over the Puget lowland, stretching from the Olympic Peninsula clear over to the Cascade Range." Erratics can be found at altitudes up to about in the

Enumclaw Enumclaw ( ) is a city in King County, Washington, United States. The population was 12,543 at the 2020 census. The Enumclaw Plateau, on which the city resides, was formed by a volcanic mudflow (lahar) from Mount Rainier approximately 5,700 ye ...

area, along with kames,

drumlin A drumlin, from the Irish word ''droimnín'' ("littlest ridge"), first recorded in 1833, in the classical sense is an elongated hill in the shape of an inverted spoon or half-buried egg formed by glacial ice acting on underlying unconsolidated ...

s, and perhaps also the unique Mima mounds. The soil of Seattle, the county's (and state's) largest city, is approximately 80%

glacial drift In geology, drift is a name for all sediment (clay, silt, sand, gravel, boulders) transported by a glacier and deposited directly by or from the ice, or by glacial meltwater. Drift is often subdivided into (unsorted and) unstratified drift (glaci ...

, most of which is Vashon glacial deposits ( till), and nearly all of the city's major named hills are characterized as drumlins (Beacon Hill, First Hill, Capitol Hill, Queen Anne Hill) or drift uplands (Magnolia, West Seattle)., narrated by Nick Zentner (Central Washington University Department of Geological Sciences). Uploaded March 2, 2015 by Hugefloods.com (Nick Zentner and Tom Foster: Discover the Ice Age Floods). Boulders greater than 3 meters in diameter are "rare" in the Vashon till, but can be found, as seen in the table below.

List of boulders

References

;Notes ;Sources * *. * * * * * * * * * *

External links

Washington glacial erratics project
at University of Washington dept. of earth and space sciences {{Washington erratics Landforms of King County, Washington King County

List of boulders

References

Further reading

External links