When paleontologists speak of something being “fossilized,” they mean the object or an impression of the object has been preserved through petrification. Linguists, SLA researchers, and ESL/EFL instructors use the metaphor of fossilization to describe the manner in which some language learners never achieve full competence in particular linguistic features (Ellis 29).
There are limits to the metaphor, but essentially fossilization signifies that a learner’s progress in certain linguistic areas may reach a ceiling where improvement comes to a halt. L1 or interlanguage features continue to manifest in communicative tasks (i.e. they are preserved), regardless of the learner’s efforts to overcome their interference. Scovel writes,
“The permanent persistence of foreign accents brought about by the interference of the mother tongue on any second language learned after puberty is the foundation for the critical period hypothesis and suggests…that at least for pronunciation, mother tongue transfer for adult L2 learners leaves a salient and perhaps indelible imprint” (48).
That being said, while fossilization is “persistent,” it is not necessarily irreversible, although a learner’s age, social context, motivation, and other key influences may factor into the difficulty of overcoming it.
Kaufmann, Steve. “Fossilization in Language Learning.” YouTube, uploaded by Steve Kaufmann – lingosteve, 13 Dec. 2011, https://www.youtube.com/watch?v=s4zI-raPnEQ.
Thornbury, Scott. “Fossilization: Is It Terminal, Doctor?” YouTube, uploaded by The New School, 04 Aug. 2014, https://www.youtube.com/watch?v=V_XTRu0igNA.
Ellis, Rod. Second Language Acquisition. Oxford, 1997.
National Park Service. “Palaeovespa florissantia.” Wikicommons, n.d., https://commons.wikimedia.org/wiki/File:Palaeovespa_florissantia.jpg.
Scovel, Tom. Learning New Languages. Heinle & Heinle, 2001.