Puget Sound region

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The Puget Sound region is a coastal area of the Pacific Northwest in the U.S. state of Washington, including Puget Sound, the Puget Sound lowlands, and the surrounding region roughly west of the Cascade Range and east of the Olympic Mountains. It is characterised by a complex array of saltwater bays, islands, and peninsulas carved out by prehistoric glaciers.

Puget Sound


Evening on Puget Sound by Edward S. Curtis, 1913

The Puget Sound region was formed by the collision and attachment of many terranes ("microcontinents") to the North American Plate between about 50 to 10 million years ago.[1] About 15,000 years ago, the Puget Sound region was covered by a lobe of the Cordilleran Ice Sheet. The ice was about 3,000 feet (900 m) thick in the vicinity of Seattle.[2] By the time Captain George Vancouver found the Sound, early native people had already been there for over 5,000 years.

Logging started as early as 1853. In the 1880s logging railroads cut their way into Puget Sound. 1886 the St. Helens fire burned 300,000 acres (1,200 km2). Mount Rainier National Park started in 1899. The 1902 Yacolt fire burned 600,000 acres (2,400 km2). Olympic National Park was established in 1938.[3]

George Vancouver explored Puget sound in 1792. Vancouver claimed it for Great Britain on 4 June 1792, naming it for one of his officers, Lieutenant Peter Puget. It became part of the Oregon Country, and became U.S. territory when the 1846 Oregon Treaty was signed.

After arriving along the Oregon Trail, many settlers wandered north to what is now Washington and settled the Puget Sound area. The first non-indigenous settlement was New Market (now known as Tumwater) in 1846. In 1853 Washington Territory was formed from part of Oregon Territory. In 1888 the Northern Pacific railroad line reached Puget Sound, linking the region to eastern states.

For a long period Tacoma was noted for its large smelters where gold, silver, copper and lead ores were treated. Seattle was the primary port for trade with Alaska and the rest of the country and for a time possessed a large shipbuilding industry. The region around eastern Puget Sound developed heavy industry during the period including World War I and World War II, and the Boeing Company became an established icon in the area.

During World War II the Puget Sound area became a focus for the war industry, with Boeing producing many of the nation's heavy bombers and the ports of Seattle, Bremerton and Tacoma available for shipbuilding.

Since 1995, Puget Sound has been recognized as an American Viticultural Area by the Alcohol and Tobacco Tax and Trade Bureau.[4]

Physical geography[edit]

Low tide on Whidbey Island

The United States Geological Survey (USGS) defines Puget Sound as a bay with numerous channels and branches; more specifically, it is a fjord system of flooded glacial valleys. Puget Sound is part of a larger physiographic structure termed the Puget Trough, which is a physiographic section of the larger Pacific Border province, which in turn is part of the larger Pacific Mountain System.[5]

Puget Sound is a large salt water estuary, or system of many estuaries, fed by highly seasonal freshwater from the Olympic and Cascade mountain watersheds.[6] Puget Sound is connected to the Strait of Juan de Fuca to the north at Admiralty Inlet, between Point Partridge on Whidbey Island and Point Wilson on the Olympic Peninsula. A second connection is Deception Pass, between West Point on Whidbey Island and Rosario Head on Fidalgo Island.[7]

Continental ice sheets have repeatedly advanced and retreated from the Puget Sound region. During the most recent glacial period, called the Fraser Glaciation, which had three phases, or stades. During the third, or Vashon Glaciation, a lobe of the Cordilleran Ice Sheet, called the Puget Lobe, spread south about 15,000 years ago, covering the Puget Sound region with an ice sheet about 3,000 feet (910 m) thick near Seattle, and nearly 6,000 feet (1,800 m) at the present Canada-US border. Since each new advance of ice scours away much of the evidence of previous ice ages, the most recent Vashon phase has left the clearest imprint on the land. At its maximum extent the Vashon ice sheet extended south of Olympia to near Tenino, and covered the lowlands between the Olympic and Cascade mountains. About 14,000 years ago the ice began to retreat. By 11,000 years ago it survived only north of the Canadian border.[8]

The Vashon Glaciation scoured the land, creating a drumlin field of hundreds of aligned drumlin hills. Lake Washington and Lake Sammamish (which are ribbon lakes), Hood Canal, and the main Puget Sound basin were carved out by glacial forces. As the ice retreated, vast amounts of glacial till were deposited throughout the Puget Sound region.[8] The soils of the region, less than ten thousand years old, are still characterized as immature.

As the Vashon glacier receded a series of proglacial lakes formed, filling the main trough of Puget Sound and inundating the southern lowlands. Glacial Lake Russell was the first such large recessional lake. From the vicinity of Seattle in the north the lake extended south to the Black Hills, where it drained south into the Chehalis River.[9] Sediments from Lake Russell form the blue-gray clay identified as the Lawton Clay. The second major recessional lake was Glacial Lake Bretz. It also drained to the Chehalis River until the Chimacum Valley, in the northeast Olympic Peninsula, melted, allowing the lake's water to rapidly drain north into the marine waters of the Strait of Juan de Fuca, which was rising as the ice sheet retreated.[9]

As icebergs calved off the toe of the glacier, their embedded gravels and boulders were deposited in the chaotic mix of unsorted till geologists call glaciomarine drift. Many beaches about the Sound display glacial erratics, rendered more prominent than those in coastal woodland solely by their exposed position; submerged glacial erratics sometimes cause hazards to navigation. The sheer weight of glacial-age ice depressed the landforms, which experienced post-glacial rebound after the ice sheets had retreated. Because the rate of rebound was not synchronous with the post-ice age rise in sea levels, the bed of what is Puget Sound, filled alternately with fresh and with sea water. The upper level of the lake-sediment Lawton Clay now lies about 120 feet (37 m) above sea level.

Snowcapped peaks are a backdrop to many Puget Sound scenes. Here, Mount Rainier is seen from Gig Harbor.

The Puget Sound system consists of four deep basins connected by shallower sills. The four basins are Hood Canal, west of the Kitsap Peninsula, Whidbey Basin, east of Whidbey Island, South Sound, south of the Tacoma Narrows, and the Main Basin, which is further subdivided into Admiralty Inlet and the Central Basin.[10] Puget Sound's sills, a kind of submarine terminal moraine, separate the basins from one another, and Puget Sound from the Strait of Juan de Fuca. Three sills are particularly significant — the one at Admiralty Inlet which checks the flow of water between the Strait of Juan de Fuca and Puget Sound, the one at the entrance to Hood Canal (about 175 ft or 53 m below the surface), and the one at the Tacoma Narrows (about 145 ft or 44 m). Other sills that present less of a barrier include the ones at Blake Island, Agate Pass, Rich Passage, and Hammersley Inlet.[11]

The depth of the basins is a result of the Sound being part of the Cascadia subduction zone, where the terranes accreted at the edge of the Juan de Fuca Plate are being subducted under the North American Plate: there has not been a major subduction zone earthquake here since the magnitude nine Cascadia earthquake; according to Japanese records, it occurred 26 January 1700. Lesser Puget Sound earthquakes with shallow epicenters, caused by the fracturing of stressed oceanic rocks as they are subducted still cause great damage. The Seattle Fault cuts across Puget Sound, crossing just north of Vashon Island and dipping under the city of Seattle.[12] To the south, the existence of a second fault, the Tacoma Fault has buckled the intervening strata in the Seattle Uplift.

Typical Puget Sound profiles of dense glacial till overlying permeable glacial outwash of gravels above an impermeable bed of silty clay may become unstable after periods of unusually wet weather and slump in landslides.[13]

The Puget Sound region has been called "Ish River country", perhaps most famously by poet Robert Sund, owing to its numerous rivers with names ending in "ish", such as the Duwamish, Samish, Skokomish, Skykomish, Snohomish, and the Stillaguamish.[14] The ish ending is from Salish language meaning "people of".[15]

Political geography[edit]

The Seattle Metropolitan area is the areas light blue. The Combined Statistical Area consists of both the light blue and dark blue areas.

The urban region designated the Puget Sound Region is centered on Seattle and consists of nine counties, two urban center cities and four satellite cities making up what has been dubbed "Pugetopolis".[16] Both urban core cities have large industrial areas and seaports plus a high-rise central business district. The satellite cities are primarily suburban, featuring a small downtown core and a small industrial area or port. The suburbs consist mostly of residences, strip malls, and shopping centers. The region is also home to numerous ports. The two largest and busiest are the Port of Seattle and Port of Tacoma, which, if combined, comprise the third largest container port in North America after Los Angeles/Long Beach and New York/New Jersey.[17]

The United States Census Bureau defines the Puget Sound region as the Seattle–Tacoma–Olympia Combined Statistical Area. This includes the Seattle metropolitan area, made up of the following counties (see Fig. STB):

Based on commuting patterns, the adjacent metropolitan areas of Olympia, Bremerton, and Mount Vernon, along with a few smaller satellite urban areas, are grouped together in the CSA. The population of this wider region is 4,269,349—almost two-thirds of Washington's population—as of 2012.[18] The Seattle CSA is the 12th largest CSA, and the 13th largest primary census statistical area in the country. The additional metropolitan and micropolitan areas included are:

A state-run ferry system, Washington State Ferries, connects the larger islands to the Washington mainland, as well as both sides of the sound, allowing cars and people to move about the greater Puget Sound region.

View of Puget Sound from the Space Needle

Flora and fauna[edit]

North Pacific Oak Woodland is one of the principal plant associations of the Puget Trough, where many of the soils are well drained mesic.[19]

It is estimated[by whom?] that more than 100 million geoducks (pronounced "gooey ducks") are packed into Puget Sound's sediments. Also known as "king clam", geoducks are considered to be a delicacy in Asian countries.


Counties of the Puget Sound region:

In addition, the San Juan Islands (all of San Juan County plus a few islands belonging to Whatcom County) are often considered part of the greater Puget Sound area.[citation needed]

Prominent islands:

Urban centers:

Satellite cities:

Other principal cities:

Military bases:

See also[edit]


  1. ^ Kruckeberg, Arthur R. (1991). The Natural History of Puget Sound Country. Seattle: University of Washington Press. pp. 10–13. ISBN 0-295-97477-X. 
  2. ^ Kruckeberg (1991), pp. 20–21.
  3. ^ Kruckeberg, Arthur R. (1999). A Natural History of the Puget Sound Basin pp.52-68
  4. ^ Code of Federal Regulations. "§ 9.151 Puget Sound." Title 27: Alcohol, Tobacco and Firearms; Part 9 — American Viticultural Areas; Subpart C — Approved American Viticultural Areas. Retrieved Jan. 30, 2008.
  5. ^ "Physiographic divisions of the conterminous U. S.". U.S. Geological Survey. Retrieved 2007-12-06. 
  6. ^ Fresh inflow ranges between a peak of about 367,000 cubic feet per second (10,400 m3/s) to a minimum of about 14,000 cubic feet per second (400 m3/s).
  7. ^ U.S. Geological Survey Geographic Names Information System: Puget Sound
  8. ^ a b Kruckeberg (1991), pp. 18–23.
  9. ^ a b Baum, Rex L.; Godt, Jonathan W.; Highland, Lynn (2008). Landslides and engineering geology of the Seattle, Washington, area. Volume 20 of Reviews in engineering geology. Geological Society of America. pp. 12–13. ISBN 978-0-8137-4120-8. 
  10. ^ Features Of Puget Sound Region: Oceanography And Physical Processes, Chapter 3 of the State of the Nearshore Report, King County Department of Natural Resources, Seattle, Washington, 2001.
  11. ^ Kruckeberg, Arthur R. (1991). The Natural History of Puget Sound Country. Seattle: University of Washington Press. pp. 61–64. ISBN 0-295-97477-X. 
  12. ^ "Ancient seismic stresses at work in Puget Sound region" Cyberwest Magazine 9 June 2004
  13. ^ Washington State Department of Ecology: "Puget Sound landslides"
  14. ^ Ingle, Schuyler (November 24, 1991). "The Time of Food : Pacific Northwest Bounty". Los Angeles Times. 
  15. ^ Denham, Kristen E.; Lobeck, Anne C. (2011). "Chapter 5". Linguistics for Everyone. Cengage. p. 145. ISBN 9781111344382. 
  16. ^ For examples of the use of "Pugetopolis" see, for example, Pugetopolis, TIME Magazine; Puget Sound: Sea Between the Mountains, at Google Books, p. 46; Frommer's Washington State, at Google Books, p. 17; and Western Cordillera and Adjacent Area, at Google Books, p. 197.
  17. ^ "2005 North American Container Traffic" (PDF). American Association of Port Authorities (AAPA). Archived from the original (PDF) on 25 March 2009. Retrieved 2009-05-28. 
  18. ^ "Annual Estimates of the Population of Combined Statistical Areas: April 1, 2010 to July 1, 2011" (CSV). 2011 Population Estimates. United States Census Bureau, Population Division. April 2012. Retrieved April 12, 2012. 
  19. ^ C.Michael Hogan (2008) Quercus kelloggii, GlobalTwitcher, ed. Nicklas Stromberg [1]

Further reading[edit]

  • Jones, M.A. (1999). Geologic framework for the Puget Sound aquifer system, Washington and British Columbia [U.S. Geological Survey Professional Paper 1424]. Reston, VA: U.S. Department of the Interior, U.S. Geological Survey.
  • Prosser, William Farrand (1903). A history of the Puget Sound country : its resources, its commerce and its people : with some reference to discoveries and explorations in North America from the time of Christopher Columbus down to that of George Vancouver in 1792, when the beauty, richness and vast commercial advantages of this region were first made known to the world. Lewis Pub. Co. Available online through the Washington State Library's Classics in Washington History collection

External links[edit]