Definition of Anvil Rock in US English:

Anvil Rock

noun

Geology
  • (In full "Anvil Rock sandstone") (the name of) a thick sandstone formation in Kentucky, Illinois, and Indiana, laid down in the Pennsylvanian (Upper Carboniferous) period.

Origin

Mid 19th century. After Anvil Rock, the name of a sandstone outcrop in Union County, Kentucky, so called on account of its shape.