Boudins are fragments of a strong layer that have been separated as a result of extension parallel to the layer. They can be regarded as the extensional counterpart of buckle folds.
Quartz vein extended into multiple boudins. Carmanville mélange, Green (Woody) Island, Newfoundland, Canada.
Two boudins of amphibolite surrounded by greenschist; mylonitic zone of metamorphic rocks beneath the Bay of Islands Ophiolite Complex, Pond Point, Bay of Islands, Newfoundland, Canada
The dark trace fossil at the centre has undergone boudinage resulting in the formation of several small quartz filled veins in the spaces between the boudins. Goldenville Group, Tancook Island, Nova Scotia, Canada.