Definition of nappe in US English:

nappe

noun

  • 1Geology
    A sheet of rock that has moved sideways over neighboring strata as a result of an overthrust or folding.

    • ‘Another important difference is that the basement of one of the Menderes nappes (dine nappe, see below) is of Neoproterozoic to Cambrian age.’
    • ‘Along the eastern margin of the nappe folds verge to the east and the cleavage fans until it dips westward.’
    • ‘In Tertiary time, the Batain nappes were unconformably overlain by carbonate and elastic rocks.’
    • ‘Stratigraphic relationships show that the Mata nappe follows a recumbent fold structure characterized by a normal and an inverted fold limb.’
    • ‘Southwest of the Dornoch Firth, the Sgurr Beag Thrust divides the Moine rocks into two major nappes.’
    • ‘Moine rocks within the Moine nappe are mainly unmigmatized psammites which locally may preserve sedimentary structures.’
    • ‘On its south side the Oytag arc is thrust over Carboniferous sandstones and limestones that are folded into spectacular nappes.’
  • 2Cooking
    The desired consistency of a sauce, at which it is thick enough to coat the back of a spoon.

    ‘it is made from a roux and milk, gently simmered and stirred until thickened to a nappe’

Origin

Late 19th century: French.

Pronunciation

nappe

/nap/