Question

What are stalagmites and stalactites? How are they formed?​

Answer 1

Answer:

stalagmites and stalactites

Speleothems, sometimes referred to as formations or decorations, are cave features formed by the deposition of minerals. ... The speleothems with which most people are familiar are stalactites and stalagmites. Stalactites grow down from the cave ceiling, while stalagmites grow up from the cave floor

Answer 2

Stalactite and stalagmite

Stalactite and stalagmitemineral formation

Stalactite and stalagmite, elongated forms of various minerals deposited from solution by slowly dripping water. A stalactite hangs like an icicle from the ceiling or sides of a cavern. A stalagmite appears like an inverted stalactite, rising from the floor of a cavern.

Stalactites hanging from the ceilings of caverns commonly exhibit a central tube or the trace of a former tube whose diameter is that of a drop of water hanging by surface tension. A drop on the tip of a growing stalactite leaves a deposit only around its rim. Downward growth of the rim makes the tube. The simplest stalactite form, therefore, is a thin-walled stone straw, and these fragile forms may reach lengths of 0.5 m (20 inches) or more where air currents have not seriously disturbed the growth. The more common form is a downward-tapering cone and is simply a thickening of the straw type by mineral deposition from a film of water descending the exterior of the pendant.

Stalagmites have thicker proportions and grow up on the bottom of a cavern from the same drip-water source, the mineral from which is deposited after the water droplet falls across the open space in the rock. Not every stalactite has a complementary stalagmite, and many of the latter may have no stalactite above them. Where the paired relation exists, however, continual elongation of one or both may eventually result in a junction and the formation of a column.

The dominant mineral in such deposits is calcite (calcium carbonate), and the largest displays are formed in caves of limestone and dolomite. Other minerals that may be deposited include other carbonates, opal, chalcedony, limonite, and some sulfides.

Conditions that favour the deposition are: (1) a source rock above the cavern; (2) downward percolation of water supplied from rain; (3) tight but continuous passageways for this water, which determine a very slow drip; and (4) adequate air space in the void to allow either evaporation or the escape of carbon dioxide from the water, which thus loses some of its solvent ability.