Manastash Ridge is a long anticline mountain ridge located in central Washington state in the United States. Manastash Ridge runs mostly west-to-east in Kittitas and Yakima counties, for approximately 50 miles. The ridge is part of the Yakima Fold Belt of east-tending long ridges formed by the folding of Miocene Columbia River basalt flows. The name Manastash comes from the Sahaptin word /máːmaštaš/, possibly meaning "we are going root digging". The highest point in Manastash Ridge is Manastash Peak at 6335 ft, located 22.4 mi west of Ellensburg, Washington. Interstate 82 crosses through the eastern portion of the ridge; the Manastash Ridge Summit is located at milepost 7 of the interstate (south of Ellensburg) or about 24 mi north of Yakima, Washington at an elevation of 2672 ft. In addition to Manastash Peak, Manastash Ridge includes the peaks of Quartz Mountain (6289 ft), Mount Clifty (6243 ft), and Lookout Mountain (6188 ft). The astronomy department of the University of Washington maintains the Manastash Ridge Observatory, located about 9 mi west-southwest of Ellensburg.