Definition of allochthonous in US English:



  • Denoting sediment or rock that originated at a distance from its present position.

    Often contrasted with autochthonous
    • ‘These rocks are also of biogeographic interest because unlike truly allochthonous terranes they are parautochthonous with respect to the craton.’
    • ‘The allochthonous units that overlie the eastern part of this terrane were probably emplaced when the Magnitogorsk volcanic arc collided with this margin in late Devonian times.’
    • ‘However, this does not prove that the Moine rocks necessarily constitute an allochthonous terrane in the North American sense.’
    • ‘The fossils of the westernmost exposures of the Hoko River Formation are allochthonous, preserved in reworked concretions within conglomerates that were deposited as part of a submarine fan system during late Eocene time.’
    • ‘Although some skeletal remains are evidently allochthonous, other remains are probably parautochthonous.’


Early 20th century: from allo- ‘other’ + Greek khthōn ‘earth’ + -ous.