English: Cinder cone in the Holocene of Idaho, USA.

Grassy Cone is a dormant, vegetation-covered cinder cone volcano in Idaho's Craters of the Moon Lava Field. Cinder cones are relatively small, steep-sided cones of loose igneous debris. They have few eruptions and a relatively large summit crater. Cinder cones are principally composed of scoria and vesicular basalt. This one was active in the Holocene - a lava flow sourced to Grassy Cone dates to ~7,360 years ago. The summit crater area is complex and shows remnants of five separate, partly-overlapping craters. When it was active, it erupted basaltic lava, air-fall ash, and air-fall lapilli. When seen in map view, Grassy Cone is elongated, not subcircular in shape as most cinder cones are.

Locality: Grassy Cone (view from North Crater Flow Trail), northwestern side of Route 53, northwestern corner of Craters of the Moon National Monument, northern margin of the Snake River Plain, southern Idaho, USA (43˚ 27' 18.05" North latitude, 113˚ 34' 55.78" West longitude)