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CRATER , the cavity at the mouth of a volcanic duct, usually funnel-shaped or presenting theSee also: form of a bowl, whence the name, from the Gr
.
Kpari]p, a bowl
.
A volcanic See also: hill may have a single crater at, or near, its
See also: summit, or it may have several minor craters on its flanks: the latter are sometimes called " adventitious craters " or " craterlets." Much of the loose ejected material, falling in the neighbourhood of the vent, rolls down the inner See also: wall of the crater, and thus produces a stratification with an inward dip
.
The crater in an active See also: volcano is kept open by intermittent explosions, but in a volcano which has become dormant or See also: extinct the vent may become plugged, and the bowl-shaped cavity may subsequently be filled with See also: water, forming a crater-lake, or as it is called in the See also: Eifel a Maar
.
In some basaltic cones, like those of the See also: Sandwich Islands, the crater may be a broad shallow pit, having almost perpendicular walls, with See also: horizontal stratification
.
Such hollows are consequently called pit-craters
.
The name caldera (Sp. for cauldron) was suggested for such pits by Capt
.
C
.
E
.
Dutton, who regarded them as having been formed by subsidence of the walls
.
The See also: term caldera is often applied to bowl-shaped craters in See also: Spanish-speaking countries
.
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