Category Science

These thin, hollow tubes also form from dissolved particles in water, dripping slowly through the roof of a cave. They may grow into stalactites if the water keeps dripping for a very long time.

These tubes form when calcium carbonate or calcium sulfate dissolved in the water comes out of solution and is deposited. In soda straws, as each drop hovers at the tip, it deposits a ring of mineral at its edge. It then falls and a new drop takes its place. Each successive drop of water deposits a little more mineral before falling, and eventually a tube is built up. Stalagmites or flowstone may form where the water drops hit the cave floor.

Soda straws are some of the most fragile of speleothems. Like helictites, they can be easily crushed or broken by the slightest touch. Because of this, soda straws are rarely seen within arms’ reach in show caves or others with unrestricted access. Kartchner Caverns in southern Arizona has well-preserved soda straws because of its recent discovery in 1974 and highly regulated traffic.

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These hang down like icicles. They form in the same way as stalagmites, from rocky particles dissolved in water, this time dripping from the caves ceiling.

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.

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Water dripping onto the cave floor leaves behind tiny rocky particles that were dissolved in it. As the dripping continues, these particles can build up form a pillar of rock, or stalagmite.

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.

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Caves are underground spaces or hole that are large enough for someone to enter. They form in many different ways, but mostly because of rock in the Earth’s surface being worn away or crumbling. Caves usually have lots of interesting and exciting features to explore.

There are many types of caves formed through different processes: some are small, and it is difficult for man to penetrate into; others, on the contrary, stretch underground for tens or hundreds of kilometres, reaching depths of over 2,000 m. Formation processes control length, development and shape of a cave, and also the difficulties that will arise when exploring them. Most of the longest and deepest caves do not consist in an isolated cavity, but they form a system, which at times may be very complex, made of rooms, sinkholes, shafts, meanders, canyons, interconnecting galleries, which are arranged to form a system or karst complex.
Large quantities of underground water move through karst systems, caves may therefore be classified in different sub-areas, i.e. occupied by air and completely dry or scoured by streams, they may be flooded at times, or permanently invaded by fresh and salt water.

Caves are found all over our planet. Some are small, single spaces, but others contain many chambers, linked by tunnels to form a huge maze of different areas. Although most caves are found in rock, some form in ice or lava.

Solutional caves

These are the most common type of cave. They are created when a build up acidic water dissolves the rock around it. Holes and tunnels start to appear, getting bigger and bigger as more rock dissolves and is washed away.

Solution caves are formed when groundwater seeps underground via cracks, faults, joints, bedding places, and other surface openings. Over geological epochs, small cracks in the rock become large cave systems. Limestone solution caves are very picturesque as they are often adorned with cave formations like stalactites and stalagmites formed by calcium carbonate precipitation. Such caves are formed by the dissolution of limestone by acidic water (water with dissolved carbonic acid).

Lava caves

When lava flows slowly over land around a volcano, it can harden on the surface, leaving liquid lava flowing underneath. This liquid drains away, leaving a hollow tube of rock that forms a cave.

When hot liquid lava flows down the slope of a volcano, the surface of the lava cools and solidifies. However, hot liquid lava continues to flow beneath the solidified surface and when the flow stops, a hollow tube remains. Such types of caves are called lava tubes. Lava mold caves, rift caves, inflationary caves, and volcanic conduits are other caves formed by volcanic activity. The Kazumura Cave in Hawaii is an example of a 65.8 km long lava tube.

Ice caves

Ice melting on top of a glacier can form a stream or waterfall that flows through the glacier. Eventually, this flowing water will hollow out part of the glacier, creating an ice cave.

The second type of ice cave occurs either when frigid winter air settles into downward-leading caverns where it cannot be forced out or when moisture freezes in currents of cold air. Frozen lakes, icicles, and ice draperies are common formations. Helictite-like icicles also form where air currents deflect the freezing water. The splendid ice deposits formed in the lava caves of the northwestern United States are dwarfed by the limestone ice-cave systems of the Alps.

Sea Caves

These are formed by waves constantly battering against cliffs along the seashore. This leads to cracks appearing in the cliffs that get larger as beating waves continue to wear away the rock.

Sea caves are often a major tourist attraction. Some sea caves can be accessed only by boats during low tide while others are more easily accessible and occur along beaches where it is possible to walk into the caves. Cathedral Cove Sea Cave, in Coromandel, New Zealand is an example of a sea cave.

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This is where a river starts, high up in the mountains. The source, or place where the river starts from, could be a springs or a lake, or even a melting glacier. A river can have more than one source.

The source is the farthest point of the river stream from its estuary or its confluence with another river or stream. Rivers are usually fed by many tributaries. The farthest stream is called the head-stream or head water. There is sometimes disagreement on which source is the head water, hence on which is the true source. Headwaters are usually in mountains. Glacial headwaters are made by melting glaciers.

The source is where a river begins, and the mouth is where it joins the sea. The source of a river generally discharges water with less force leading to the formation of Interlocking spurs.

The river mouth is the opposite of a river source. The mouth is where the river ends as it meets the ocean, and may have a river delta.

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A river is a natural channel of fresh water that flows across the Earth’s surface. All rivers start in mountains or hills and flow down towards the sea or ocean, or into another large area of water. They may be short or flow for hundreds of kilometres.

Rivers are part of the hydrological cycle; water generally collects in a river from precipitation through a drainage basin from surface runoff and other sources such as groundwater recharge, springs, and the release of stored water in natural ice and snowpacks (e.g., from glaciers). Potamology is the scientific study of rivers, while limnology is the study of inland waters in general. Most of the major cities of the world are situated on the banks of rivers, as they are, or were, used as a source of water, for obtaining food, for transport, as borders, as a defensive measure, as a source of hydropower to drive machinery, for bathing, and as a means of disposing of waste.

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