visible along Balch Creek Canyon and Northwest Cornell Road. The West Hills were later covered by wind-deposited silts that become unstable when saturated with water. Stream bank instability and siltation are common, and landslides deter urban development at higher elevations. Roughly long, the park is less than wide near downtown Portland and about wide at its northwestern end. It extends along the West Hills from West Burnside Street near downtown Portland to where the Willamette River divides to flow around Sauvie Island. Covering most of the east face of the ridge above the Willamette River, it is bounded by West Burnside Street on the south, Northwest Skyline Boulevard on the west, Northwest Newberry Road on the north, and Northwest St. Helens Road (U.S. Route 30) on the east. Elevations above sea level vary from near U.S. Route 30 at the base of the ridge to about near the crest of the ridge along Northwest Skyline Boulevard. In 2008 Forest Park ranked 19th in size among the largest city parks in the United States, according to The Trust for Public Land. The trust's list included state parks, national parks, county parks, regional parks, and national wildlife refuges, as well as municipally owned parks located within cities. Chugach State Park in Anchorage, Alaska, was in first place with . Portland author Marcy Houle says that the park "captures the essence of what is natural and wild and beautiful about the Northwest... From this forest sanctuary, panoramic views of the city of Portland, the Willamette and Columbia rivers, and five major peaks of the Cascade Range ... can be seen through the tall fir trees. From its inception ..., Forest Park has been a refuge for both people and wildlife, and an integral part of the environment of Portland." Ecology Vegetation Forest Park lies in the Coast Range ecoregion designated by the U.S. Environmental Protection Agency (EPA). In its natural state, the forest consists mainly of three tree species, Douglas-fir, western hemlock, and western red cedar, and smaller numbers of grand fir, black cottonwood, red alder, bigleaf maple, madrone, and western yew. Much of the forest that existed here before 1850 was gone by 1940. The stage of re-growth in the forest depends on when it was last logged or burned. In the mid-1990s, about one percent of the total vegetation in the park consisted of grasses, bracken, thistle, and fireweed in sections