n. a bowl-shaped opening at the top of a volcano [syn: crater]
A volcanic crater is a roughly circular depression in the ground caused by volcanic activity. It is typically a bowl-shaped feature within which occurs a vent or vents. During volcanic eruptions, molten magma and volcanic gases rise from an underground magma chamber, through a tube-shaped conduit, until they reach the crater's vent, from where the gases escape into the atmosphere and the magma is erupted as lava. A volcanic crater can be of large dimensions, and sometimes of great depth. During certain types of explosive eruptions, a volcano's magma chamber may empty enough for an area above it to subside, forming a type of larger crater known as a caldera.
Usage examples of "volcanic crater".
One of Stafford's famed medallions was found on the lander wreckage, but Stafford's tracks indicate he left that site, traveling for unknown reasons farther into the desert, where his buggy was found in a small volcanic crater.
He knew that the island was the remains of an ancient volcanic crater, eroded and decomposed by centuries of weathering.
It was clearly an old volcanic crater: bare, reddish-gray rock walls, an eroded cone.
John Janders a third on the slopes of Punfchbowl, the volcanic crater that rose on the edge of the city.
The crater is a volcanic crater, the volcano forms part of an island in a big inland sea.
Near the following midday, they reached the rim of a great volcanic crater containing a marvelous blue lake.
Starting over, Horife said, The basin in which Carcosa lies is an ancient volcanic crater, you see.
Dwarfed by distance, but still massively, craggily tremendous, there loomed the encircling rampart of the volcanic crater upon whose floor the fortress lay.
At length we arrived there, and, having ascertained that there was a large lake on top of the mountains, ascended three thousand feet more till we came to a precipitous cliff or edge, to find a great sheet of water some twenty miles square lying fifteen hundred feet below us, and evidently occupying an extinct volcanic crater or craters of vast extent.
As the ship drifted we presently noted that it was taking a circular course paralleling the rim of the huge volcanic crater above which we were descending.