Buldir Island (also sometimes written Buldyr; Aleut: Idmaax) is a small island in the western Aleutian Islands of the U.S. state of Alaska. It lies midway between the Near Islands in the West and the Rat Islands in the East. It is the most westerly of the Aleutian Islands which formed as a result of volcanic activity in the late Quaternary or Recent times. The rocks from which the island formed are of two different ages with a considerable time gap. The rocks of the older dome are mainly olivine basalts and the younger dome consists of hornblende basalts and basaltic andesites. That this island is younger than some of the neighboring islands is also suggested by the fact that there are fewer species of flowering plant on this island.