The Clatsop Plains are an area of wetlands and sand dunes between the Northern Oregon Coast Range

Northern Oregon Coast Range

The Northern Oregon Coast Range is the northern section of the Oregon Coast Range, in the Pacific Coast Ranges physiographic region, located in the northwest portion of the state of Oregon, United States. This section of the mountain range, part of the Pacific Coast Ranges, contains peaks as high...

 and Pacific Ocean

Pacific Ocean

The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...

 in northwestern Oregon

Oregon

Oregon is a state in the Pacific Northwest region of the United States. It is located on the Pacific coast, with Washington to the north, California to the south, Nevada on the southeast and Idaho to the east. The Columbia and Snake rivers delineate much of Oregon's northern and eastern...

 in the United States

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

. They stretch from near the mouth of the Columbia River

Columbia River

The Columbia River is the largest river in the Pacific Northwest region of North America. The river rises in the Rocky Mountains of British Columbia, Canada, flows northwest and then south into the U.S. state of Washington, then turns west to form most of the border between Washington and the state...

 south to the vicinity of Tillamook Head

Tillamook Head

Tillamook Head is a high promontory on the Pacific coast of northwest Oregon in the United States. It is located in west-central Clatsop County, approximately 5 mi southwest of Seaside. The promontory forms a steep rocky bluff on the ocean, approximately 1,200 ft high, forested with...

 near Seaside

Seaside, Oregon

Seaside is a city in Clatsop County, Oregon, United States. The name Seaside is derived from Seaside House, a historic summer resort built in the 1870s by railroad magnate Ben Holladay. The city's population was 6,457 at the 2010 census.-History:...

. The plains are drained by several coastal rivers include the Skipanon River

Skipanon River

The Skipanon River is a tributary of the Columbia River, approximately long, on the Pacific coast of northwest Oregon in the United States. It is the last tributary of the Columbia on the Oregon side, draining an area of coastal bottom land bordered by sand dunes and entering the river from the...

 and Lewis and Clark River

Lewis and Clark River

The Lewis and Clark River is a tributary of the Columbia River, approximately long, in northwest Oregon in the United States. It drains of the Northern Oregon Coast Range in the extreme northwest corner of the state, entering the Columbia near its mouth. Near the river's mouth is the site of...

, which flow parallel to the coast and empty into the Columbia at Youngs Bay

Youngs Bay

Youngs Bay, or Youngs River Bay, is located in the northwestern corner of the U.S. state of Oregon. The Youngs River meets the Columbia River at this point, which is situated between Astoria and Warrenton. There are two bridges that cross the bay, with the busiest being Old Youngs Bay Bridge, a...

 near Astoria

Astoria, Oregon

Astoria is the county seat of Clatsop County, Oregon, United States. Situated near the mouth of the Columbia River, the city was named after the American investor John Jacob Astor. His American Fur Company founded Fort Astoria at the site in 1811...

. The plains are named for the Clatsop

Clatsop

The Clatsop are a small tribe of Chinookan-speaking Native Americans in the Pacific Northwest of the United States. In the early 19th century they inhabited an area of the northwestern coast of present-day Oregon from the mouth of the Columbia River south to Tillamook.-Language:Clatsop in the...

 tribe of Native Americans

Native Americans in the United States

Native Americans in the United States are the indigenous peoples in North America within the boundaries of the present-day continental United States, parts of Alaska, and the island state of Hawaii. They are composed of numerous, distinct tribes, states, and ethnic groups, many of which survive as...

  who lived in the area at the time of the arrival of Europe

Europe

Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...

ans at turn of the 19th century.

These plains were developed from sand filling in the shoreline during the late Quaternary age. The northern portion is a result of the creation of the south jetty

Jetty

A jetty is any of a variety of structures used in river, dock, and maritime works that are generally carried out in pairs from river banks, or in continuation of river channels at their outlets into deep water; or out into docks, and outside their entrances; or for forming basins along the...

on the Columbia River built in 1885. Within the plain are several lakes including Cullaby, Smith, and Coffenbury which are filled by groundwater and not local streams or rivers.