Portal:Oregon/Selected article/7

The Oregon Coast Range is a mountain range running north-south in western Oregon that extends over 200 miles from the Columbia River on the border of Oregon and Washington south to the middle fork of the Coquille River in the United States. It is thirty to sixty miles wide and averages around 1,500 feet in elevation. The oldest portions of the range are over 60 million years old, with volcanics and a forearc basin as the primary mountain building processes responsible for the range. It is part of the larger Pacific Coast Range that extends over much of the western edge of North America. The range creates a rain shadow effect for the Willamette Valley that lies to the east of the mountains, creating a more stable climate and significantly less rain than the coastal region of the state. The Oregon Coast Range is divided into three separate sections: Northern, Central, and Southern. In the south is the oldest portion of the range with formation beginning in the Paleocene era with the Roseburg volcanics, while the newest section is the northernmost portion formed first with the Siletz River Volcanics. The Central and Northern sections contain more sedimentary rocks from the mud, silt, sand, and other volcanic debris than the lower Southern section. Also, the Oregon Coast Range is home to over 50 mammal species, over 100 species of birds, and nearly 30 reptile or amphibian species that spent significant portions of their life cycle in the mountains.