Volcanic formations are geological features that are created by the eruption of molten rock from a volcano. Cones, which are five-letter solutions to this crossword, are the most common type of volcanic formation and are typically steep-sided mounds or hills that form around a volcano's vent. FUMAROLES, which are nine-letter solutions to this crossword, are openings in the Earth's surface that emit steam and gases such as sulfur dioxide. They are usually found near volcanoes and hot springs.