A mamelon is a rock formation created by eruption of relatively thick or stiff lava

Lava

Lava refers both to molten rock expelled by a volcano during an eruption and the resulting rock after solidification and cooling. This molten rock is formed in the interior of some planets, including Earth, and some of their satellites. When first erupted from a volcanic vent, lava is a liquid at...

 through a narrow vent in the bedrock. Because the lava is not fluid, it does not flow away; instead it congeals around the vent, forming a small hill or mound on the surface. The outflow from successive eruptions forms additional layers on top, and the resulting pile of layers may stand over 100 metres (328.1 ft) above the surrounding surface.

The term was coined by the French

France

The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...

 explorer and naturalist Jean Baptiste Bory de Saint-Vincent

Jean Baptiste Bory de Saint-Vincent

Jean Baptiste Bory de Saint-Vincent was a French naturalist. He was born at Agen...

, to describe the central peak of the Dolomieu Crater in the Piton de la Fournaise

Piton de la Fournaise

Piton de la Fournaise : "Peak of the Furnace" is a shield volcano on the eastern side of Réunion island in the Indian Ocean. It is currently one of the most active volcanoes in the world, along with Kīlauea in the Hawaiian Islands , Stromboli, Etna and Mount Erebus in Antarctica...

 volcano on Réunion

Réunion

Réunion is a French island with a population of about 800,000 located in the Indian Ocean, east of Madagascar, about south west of Mauritius, the nearest island.Administratively, Réunion is one of the overseas departments of France...

.

Hanging Rock

Hanging Rock, Victoria

Hanging Rock , in Central Victoria, Australia, is a distinctive geological formation, 718m above sea level on the plain between the two small townships of Newham and Hesket, approximately 70 km north-west of Melbourne and a few kilometres north of Mount Macedon, a former volcano...

 in Australia

Australia

Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...

is another example of a mamelon.