- Geologic Map of the East Half of the Bellevue South 7.5’ x 15’ Quadrangle, Issaquah Area, King County, Washington
The Issaquah area includes several of the most outstanding geologic features of the eastern Puget Lowland region. Folds have warped thousands of meters of Tertiary sedimentary and volcanic rocks. Several hundred meters of both glacial and postglacial sediment have accumulated in a deep glacial trough, which is now partly occupied by Lake Sammamish but which was previously the conduit for massive volumes of meltwater during ice-sheet occupation and retreat. The eastern projection of an east-west-oriented crustal structure, which reflects Tertiary through Holocene fault displacement, extends across the eastern part of the map area.
- Lake Sammamish (wa100.dnr.wa.gov)
Don’t have time to visit Washington’s wild and scenic backcountry? Some of the exciting geology Washington has to offer may be just a stone’s throw away from your home. Lake Sammamish, a popular suburban beach getaway, lies just to the east of Seattle. At the lake’s southern end, Lake Sammamish State Park boasts a whole array of activities on water and land for the whole family. It’s certainly worth a day trip. For a geology-enthusiast, however, a pleasant afternoon by the lake can also involve imagining what the valley looked like during the last ice age. Take a break from paddling and picnicking to think about how geologic forces created this well-loved recreation area.
Washington Trails Association
- Lake Sammamish State Park (wta.org)
A beach, forests, wetlands, and the potential to spot wildlife; Lake Sammamish State Park has it all. And people have been appreciating what the area has to offer for generations – the land around the lake is culturally significant as a gathering place for several Native American tribes.
- Lake Sammamish (Wikipedia)
Lake Sammamish is a freshwater lake 8 miles (13 km) east of Seattle in King County, Washington, United States. The lake is 7 miles (11 km) long and 1.5 miles (2 km) wide, with a maximum depth of 105 feet (32 m) and a surface area of 8 sq mi (21 km2). It lies east of Lake Washington and west of the Sammamish Plateau, and stretches from Issaquah in the south to Redmond in the north. At Issaquah it is fed by Issaquah Creek, and at Redmond it drains to Lake Washington via the Sammamish River, named after the native people who once lived along its entire length.
