Definition of Facies:

part of speech: noun

In nat. hist., any common resemblance or aspect among the rocks, plants, animals, or fossils of any area or epoch.

Usage examples:

• Should it be replied, as it may fairly be, that this correspondence from which the synchronism of distant formations is inferred, is not a correspondence between particular species or particular genera, but between the general characters of the contained assemblages of fossils- between the facies of the two Faunas; the rejoinder is, that though such correspondence is a stronger evidence of synchronism it is still an insufficient one. Herbert Spencer in "Essays: Scientific, Political, & Speculative, Vol. I".

• C might be omitted in the language without loss, since one of its sounds might be supplied by s, and the other by k, but that it preserves to the eye the etymology of words, as face from facies captive from captivus"- Johnson. Robert Gordon Latham in "The English Language".

• M. Barrande pointed out that these primordial trilobites have a peculiar facies of their own dependent on the multiplication of their thoracic segments and the diminution of their caudal shield or pygidium. Sir Charles Lyell in "The Student's Elements of Geology".