Their large size and unusual composition make these buttes particularly illustrative of an unusual aspect of basaltic volcanism. The highest of the cones rises 800 feet above the floodplain of the Snake River Plain, near the confluence with Henrys Fork. The largest buttes are probably not more than 10,000 years old. Eruptions were of a highly explosive nature owing to molten magma coming in contact with water at or near the surface. Wind erosion since production of the volcanic tuff has carved pillars, caves, channels and large circular basins, particularly on the southwest side of North Menan Butte.
Visitation also exacerbates the impacts to vegetation and soils.
However, unlawful incursions still occur in this area of the landmark with resultant soil erosion and destruction of native plant species. BLM has strengthened the road closure on the west side of the north butte and concentrated patrols in that area, resulting in less use of the butte by ORVs. A portion of the North Menan Butte is in private ownership and presently is used for agriculture and home development. Private lands on the lower slopes of North and South Menan Buttes are being developed into homesites. While building activity may be seen as intruding on the natural setting of the area, the presence of homes in the area has curtailed unauthorized ORV use of the eastern part of the north butte.