allochthon
/əˈlɒkθ(ə)n/ /əˈlɒkθɒn/(also allochthone) Geology
noun
An allochthonous rock or mineral formation; especially a part of a faulted formation that has been displaced by tectonic forces. Contrasted with autochthon.
Origin
Late 19th century; earliest use found in Nature: a weekly journal of science. Apparently from allo- + -chthon.