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For the geographical region, see Puget Sound region. For the university in this region, see University of Puget Sound.  Puget Sound (pronounced /ˈpjuːdʒɪt/) is a sound in the U.S. state of Washington. It is a complex estuarine system of interconnected marine waterways and basins, with one major and one minor connection to the Strait of Juan de Fuca and the Pacific Ocean—Admiralty Inlet being the major connection and Deception Pass being the minor. Flow through Deception Pass accounts for about 2% of the total tidal exchange between Puget Sound and the Strait of Juan de Fuca.[1] Puget Sound extends approximately 100 miles (160 km) from Deception Pass in the north to Olympia, Washington in the south. Its average depth is 205 feet (62 m) and its maximum depth, off Point Jefferson between Indianola and Kingston, is 930 feet (280 m).[1] The term "Puget Sound" is used not just for the body of water but also the the general region centered on the sound, including the Seattle metropolitan area, home to about 4.2 million people.
[edit] Name and definitionThere are various definitions of the extent and boundaries of Puget Sound. In 1792 George Vancouver gave the name "Puget's Sound" to the waters south of the Tacoma Narrows, in honor of Peter Puget, a lieutenant accompanying him on the Vancouver Expedition. The name later came to be used for the waters north of Tacoma Narrows as well.[2] The USGS defines Puget Sound as all the waters south of three entrances — the main entrance at Admiralty Inlet being a line between Point Wilson, on the Olympic Peninsula, and Point Partridge, on Whidbey Island; a second entrance at Deception Pass being a line from West Point, on Whidbey Island, to Deception Island and Rosario Head, on Fidalgo Island; and a third entrance at the south end of the Swinomish Channel, which connects Skagit Bay and Padilla Bay.[3] Under this definition, Puget Sound includes the waters of Hood Canal, Admiralty Inlet, Possession Sound, Saratoga Passage, and others. It does not include Bellingham Bay, Padilla Bay, the waters of the San Juan Islands or anything farther north. Another definition, given by NOAA, subdivides Puget Sound into five basins or regions. Four of these correspond to areas within the USGS definition, but the fifth one, called "Northern Puget Sound" includes a large additional region. It is defined as bounded to the north by the international boundary with Canada, and to the west by a line running north from the mouth of the Sekiu River on the Olympic Peninsula.[4] Under this definition significant parts of the Strait of Juan de Fuca and the Strait of Georgia are included in Puget Sound, with the international boundary marking an abrupt and hydrologically arbitrary limit. According to Arthur Kruckeberg, the term "Puget Sound" is sometimes used for waters north of Admiralty Inlet and Deception Pass, especially for areas along the north coast of Washington and the San Juan Islands, essentially equivalent to NOAA's "Northern Puget Sound" subdivision described above. Kruckeberg uses the term "Puget Sound and adjacent waters".[5] An alternative term for Puget Sound, still used by only some Native Americans and environmental groups, is Whulge (or Whulj), an Anglicization of the Lushootseed name 'WulcH, which means "Salt Water".[6] Since 2009 the term Salish Sea has been established by the United States Board on Geographic Names as the collective waters of Puget Sound, the Strait of Juan de Fuca, and the Strait of Georgia. Sometimes the terms "Puget Sound" and "Puget Sound and adjacent waters" are used for not only Puget Sound proper but also for waters to the north, such as Bellingham Bay and the San Juan Islands region.[5] [edit] HistorySee also Puget Sound region.  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 was originally administered from Fort Vancouver as part of the Hudson's Bay Company's Columbia Department, but became U.S. territory when the 1846 Oregon Treaty was signed. The first European settlement in the Puget Sound area was that of Fort Nisqually, in 1833, a farm and trading post of the British Puget Sound Agricultural Company a subsidiary of the Hudson's Bay Company. After arriving along the Oregon Trail, many settlers wandered north to what is now Washington State and settled the Puget Sound area. The first American 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. [edit] Hydrology 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 physiographical 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.[7] Puget Sound is a very large salt water estuary, or system of many estuaries, fed by highly seasonal freshwater from the Olympic and Cascade Mountain watersheds. The mean annual river discharge into Puget Sound is 41,000 cubic feet per second (1,200 m3/s), with a monthly average maximum of about 367,000 cubic feet per second (10,400 m3/s) and minimum of about 14,000 cubic feet per second (400 m3/s). Puget Sound's shoreline is 1,332 miles (2,144 km) long, encompassing a water area of 1,020 square miles (2,600 km2) and a total volume of 26.5 cubic miles (110 km3) at mean high water. The average volume of water flowing in and out of Puget Sound during each tide is 1.26 cubic miles (5.3 km3). The maximum tidal currents, in the range of 9 to 10 knots, occurs at Deception Pass.[1] 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.[8] 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/53 m below the surface), and the one at the Tacoma Narrows (about 145 ft/44 m). Other sills that present less of a barrier include the ones at Blake Island, Agate Pass, Rich Passage, and Hammersley Inlet.[5] Tides in Puget Sound are of the mixed type with two high and two low tides each tidal day. These are called Higher High Water (HHW), Lower Low Water (LLW), Lower High Water (LHW), and Higher Low Water (HLW). The configuration of basins, sills, and interconnections cause the tidal range to increase within Puget Sound. The difference in height between the Higher High Water and the Lower Low Water averages about 0.3 feet (0.091 m) at Port Townsend on Admiralty Inlet, but increases to about 14.4 feet (4.4 m) at Olympia, the southern end of Puget Sound.[1] [edit] GeologyThe Sound has been reshaped by the scouring action and till deposition of the Wisconsin Glaciation, which extended in this region as far south as Olympia; the soils of the region, less than ten thousand years old, are still characterized as immature. During glacial maximum a large meltwater lake formed at the icewall's forefront, drained by the Chehalis River; its sediments form the blue-gray clay identified as the Lawton Clay. 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 provide hazards to navigation. The sheer weight of glacial-age ice depressed the landforms, which experienced isostatic 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.  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.[9] 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.[10] [edit] TransportationA unique state-run ferry system, the 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.  [edit] Flora and faunaGeoduck: It is estimated that more than 100 million geoducks are packed into Puget Sound's sediments. Also known as "king clam," geoducks are considered to be a delicacy in Asian countries. Orcas are famous throughout the Sound, and are a large tourist attraction. Salmon flow in and out of Puget Sound and are a main food source for many marine animals. Pinnipeds include the harbor seal, the Stellar Sea Lion, the California Sea Lion, and the occasional Northern Elephant Seal. Minke, Humpback, and Grey Whales also live in the waters. [edit] Prominent islands[edit] See also
[edit] References
[edit] Further reading
[edit] External links
Coordinates: 47°36′N 122°27′W / 47.6°N 122.45°W |
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