monadnock

A monadnock is an isolated hill or small mountain that rises abruptly from a surrounding plain. It forms when surrounding softer rock is eroded away over long periods, leaving a more resistant core exposed. The landscape around the feature tends to be flat or gently undulating, while the monadnock remains as a prominent, solitary high point.

Etymology and usage: The term derives from Mount Monadnock in southwestern New Hampshire, a well-known example of the landform. The name is commonly said to come from an Indigenous language and is often interpreted as meaning “a mountain that stands alone,” though exact linguistic origins are varied in sources.

Formation and rock types: Monadnocks are typically composed of rocks that resist erosion, such as granite, metamorphic rocks, quartzite, or thick-bedded volcanic rocks. They may represent remnants of a once more extensive surface or plateau that has been reduced by long-term weathering and glacial or fluvial erosion. Differential erosion, where less resistant surrounding rock wears away faster than the core, is the central mechanism behind their emergence.

Regional occurrence and significance: Monadnocks occur in various regions, including parts of New England, the midcontinent, and other areas where long erosion histories have exposed resistant blocks. They are of interest in geomorphology and physical geography as clear examples of differential erosion and landscape evolution. Mount Monadnock continues to serve as a canonical reference point for discussions of this landform.