Monster Rock is a glacial erratic on the Ephrata Erratic Fan. It is a registered feature of the Ice Age Floods National Geologic Trail, on private property in Grant County, Washington. The rock is more than 25 feet (7.6 m) tall, and 60 feet (18 m) in diameter. It is among a grouping of rocks said to have "arrived here through the great floods through Grand Coulee."
References
Sources Baker, Victor R.; Bjornstad, Bruce N.; Gaylord, David R.; Smith, Gary A.; Meyer, Scott E.; Alho, Petteri; Breckenridge, Roy M.; Sweeney, Mark R.; Zreda, Marek (2016), Pleistocene megaflood landscapes of the Channeled Scabland (PDF), The Geological Society of America, Field Guide 41 "Channeled Scablands - Ephrata Fan". FWS.gov. US Fish and Wildlife Service. March 27, 2023. "Ephrata Erratics Fan". Ice Age Floods National Geologic Trail. Ice Age Floods Institute. 2023. Retrieved December 5, 2024. "Ephrata Erratic Fan, Ice Age Floods National Geologic Trail". U.S. National Park Service. May 30, 2023. Retrieved November 14, 2023. Soennichsen, John (2012-02-21). Washington's Channeled Scablands Guide. The Mountaineers Books. ISBN 978-1-59485-484-2. OCLC 910880058. Partial preview through Google Books. Tate, Cassandra (March 26, 2008), "Ice Age Floods in Washington", HistoryLink, Seattle: History Ink
