Definition of footwall in US English:

footwall

noun

Geology
  • The block of rock that lies on the underside of an inclined fault or of a mineral deposit.

    • ‘They contain kilometre-scale blocks of igneous basement rocks, plucked by the rising diapir from the footwall of the fault.’
    • ‘Anticlinal folds occupy the mutual hanging walls of conjugate fault pairs with synclines occupying mutual footwalls between adjacent pairs.’
    • ‘At its southern boundary the terrane lies in the footwall of another north-directed thrust with Dazhuqu terrane ophiolitic rocks or Paleogene Liuqu Conglomerate in the hanging wall.’
    • ‘Normal faulting led to the unroofing of metamorphic rocks in their footwalls.’
    • ‘As a result, Triassic rocks in the hanging wall thrust onto Upper Cretaceous rocks in the footwall.’

Pronunciation

footwall

/ˈfʊtwɑl//ˈfo͝otwäl/