- 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.
Inside an abandoned building in Issaquah- Issaquah - Thumbnail History (historylink.org)
Issaquah, located east of Lake Washington along Interstate-90, has experienced two periods of rapid growth during its lengthy history. The first came in the late nineteenth century when the local economy was fueled by the coal, lumber, hop growing, and dairy industries. During the mid-twentieth century the town became somewhat dormant, then once again saw vast development. In 2003, the city was listed as the fastest growing community in the state of Washington.
- Issaquah, Washington (Wikipedia)
Issaquah (/ˈɪsəkwɑː/ ISS-ə-kwah) is a city in King County, Washington, United States. The population was 40,051 at the 2020 census. Located in a valley and bisected by Interstate 90, the city is bordered by the Sammamish Plateau to the north and the “Issaquah Alps” to the south. It is home to the headquarters of the multinational retail company Costco. Issaquah is included in the Seattle metropolitan area.
Outside an abandoned building in Issaquah- Warehouse chain Costco previously had its headquarters in Kirkland. While Costco is now headquartered in Issaquah, the city is the namesake of its “Kirkland Signature” store brand.
- Washington State Fossil Sites and Collecting Localities (fossilspot.com)
clockwise around Lake Sammamish
eastbound on Interstate 90