Tiger Mountain
What is it and why visit?
You don’t need to venture deep into the Cascades for great vistas—the view from the top of Tiger Mountain is spectacular. On a clear day, visitors can gaze out over a broad valley of lush green trees and distant lakes stretching to the edges of Redmond, Seattle, and the Olympic Mountains. This serene peak stands tall at an elevation of more than 3,000 feet, dominating the nearby landscape while humbly nodding at Mount Rainier to the south. With extensive, accessible trails and an active tectonic story, this forest playground on the edge of urban bustle is a good place for visitors to enjoy both geology and great views. The forest, which covers more than 18,000 acres of land managed by the Department of Natural Resources, even has a popular paragliding ledge at Poo Poo Point. Take to the skies on your next visit and float among the broad vistas of Issaquah and Bellevue.
Geologic story
As the faults lift up the land, the rocks of Tiger Mountain have been exposed to erosion by wind and rain
Before faults deformed the area, Tiger Mountain was a low-lying wetland where rivers met the sea. It was coastal real estate more than 40 million years too early for the Northwest boom. Layers of sand, silt, and clay containing fossils of sea creatures document the gradual retreat of the ancient seashore. As the water drew back, deep marine environments gave way to shallow deltas, rivers, and swamps, leaving behind loose sediments and muds. Around the same time, an ancient volcano near modern-day Issaquah erupted explosively, spreading volcanic rocks across Tiger Mountain. Lahars—massive floods of volcanic mud—periodically inundated these ancient swamp river valleys.
Tiger Mountain State Forest is bound by two large fault zones. A broad swath of several faults comprises the
As the faults lift up the land, the rocks of Tiger Mountain have been exposed to erosion by wind and rain. The loose swamp sediments were easily removed by these forces, leaving behind the resistant volcanic rocks and sandstones that form the backbone of the mountain.
In the late 19th century, prospectors dug coal mines on Tiger Mountain as part of the mining boom that fed the growth of Issaquah and Newcastle. Coal from Tiger Mountain fueled railways on the mountain that transported timber to market. The Iverson Railroad Trail is an example of one of these timber railroad grades.
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Fun Fact
Scientists and collectors have found amber alongside the coal deposits on Tiger Mountain. These gemstones form when buried ancient tree resin is heated and pressurized by the Earth. They contain not only insect fossils but also microfossils of ancient bacteria.
What to see and do
Access passes you may need:
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Getting There
For West Tiger Highpoint trailhead, take Interstate 90 to exit 20. Trailheads are along SE 79th Street, including Cable Line trailhead and Highpoint trailhead.
For West Tiger Poo Poo Point trailhead, take Issaquah-Hobart Road SE (Front Street S in Issaquah) 2.3 miles south of downtown Issaquah (Sunset Way and Front Street) to Poo Poo Point trailhead parking lot, adjacent to the east side of the road.
For East Tiger Summit trailhead, take State Route 18 to Tiger Summit trailhead; watch your speed on this busy section of highway for the turnoff to the East Tiger Mountain Summit parking lot; access to multiple trails.
Nearby Amenities
Photo gallery
Bibliography
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Waggoner, B., 1993, Fossil actinomycetes and other bacteria in Eocene amber from Washington State, USA: Tertiary Research, v. 14, no. 4, p. 155–160.
Walsh, Timothy, 1990, Geologic history of the Tiger Mountain State Forest. In Washington Division of Geology and Earth Resources, Washington Geologic Newsletter: Washington Division of Geology and Earth Resources, v. 18, no. 1, p. 35–36. [https://www.dnr.wa.gov/Publications/ger_washington_geology_1990_v18_no1.pdf]