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Cave mystery - The science of it all

Do you know how astronauts get a preview of life in space? By studying cave biology!

One of the things that fascinate me is caves. And mystery surrounding their formations. Stories I heard about caves when I was young bring so many facets of human behaviours and endeavours.

There is an interesting story. It seems two people stood in front of a cave. Both started imagining what would be inside. The first one thinks about demons, devils and all the evil things inhabiting the insides and harm he would face when he goes inside and just stares at it with fear.

But the other one thinks about beautiful water ways, wonderful lime stone formations, the lively unexplored life inside and dares to enter it. Need I say who this hero is? And he brought us back a wealth of knowledge from the cave and want us to enter it too.

Yes, let us go inside and find the fascinating facts about caves.

Speleology or Spelacology (also spelled spelæology or spelaeology) is the scientific study of caves and other karst features, their make-up, structure, physical properties, history, life forms, and the processes by which they form (speleogenesis) and change over time (speleomorphology). Speleology is a cross-disciplinary field that combines the knowledge of chemistry, biology, geology, physics, meteorology and cartography to develop portraits of caves as complex, evolving systems.

Cave formation begins when rainwater absorbs carbon dioxide as it falls through the atmosphere. Rain water must have carbon dioxide to become acidic. It must be acidic to chemically react to the limestone bedrock. Rainwater is absorbed by the soil into the ground.

As rainwater comes through the soil it absorbs more carbon dioxide that is being produced by plants that are dead. This changes the ground water to a weaker form of carbonic acid. As it travels down through the ground it comes to solid rock. When the rock is limestone or dolomite caves can form. Caves are formed by the dissolution of limestone. The acid slowly dissolves out the limestone along the joints, bedding planes and fractures, some of which become enlarged enough to form caves. The water reacts chemically with limestone and slowly a larger and larger space will form. This happens because the rocks are made of calcium carbonate (CaCO₃). This is what you call chemical erosion.

As the space becomes larger and larger the water can flow through. As it flows it erodes . Physical erosion washes away rock and sand. This is what makes a cave larger and forms an underground stream. Finally over hundreds of thousands of years or even millions of years the cave is formed.

Seaside cave formation occurs through weathering cause by water waves. Weathering and erosion can create caves, arches, stacks and stumps along a headland. Caves occur when waves force their way into cracks in the cliff face on the side of the shore. The water contains sand and other materials that grind away at the rock until the cracks become a cave. Hydraulic action is the predominant process. If the cave is formed in a headland, it may eventually break through to the other side forming an arch.

Cave decorations or “speleothems” begin to form later. These speleothems are the shapes you see in caves: stalactites, stalagmites and more. Speleothems form as the minerals in the water build up, one on top of the other, as the water drips and drizzles throughout the cave. It can take up to 1,000 years for one cubic inch of a speleothem to form!

The color of speleothems is determined by the mineral content. Pure calcite (crystallized limestone) is white or almost colorless. Other minerals such as iron when combined with the calcite, you will see lots of reds and oranges.

These cave decorations also reveal about earthquakes of the past!

Cave biology is quite unique and fall into three categories.

Endogean -the parts of caves that are in communication with surface soils through cracks and rock seams, groundwater seepage, and root protrusion.

Parahypogean -the threshold regions near cave mouths that extend to the last penetration of sunlight.

Hypogean -or "true" cave environments. These can be in regular contact with the surface via wind and underground rivers, or the migration of animals, or can be almost entirely isolated. Deep hypogean environments can host autonomous ecologies whose primary source of energy is not sunlight, but chemical energy liberated from limestone and other minerals by chemoautotrophic ( Chemotrophs are organisms that obtain energy by the oxidation of electron donors in their environments) bacteria.

There are three distinct cave organisms...

Cave dwellers, which specialize for only a cave living (Example: Blind Fish). Cave lovers can live part or all of their lives in caves, but can also complete a life cycle in appropriate environments on the surface (Ex: Cave Crickets). Cave guests frequents caves, and may require caves for a portion of its life cycle, but must return to the surface (Example: Hibernating reptiles).

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Permalink Reply by Dr. Krishna Kumari Challa on October 26, 2015 at 9:42am

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http://ideas.ted.com/gallery-how-caves-give-astronauts-a-preview-of...

Blood-Red Worms That Thrive in a Toxic Cave

It's wet, muddy, slimy, and smells like rotten eggs: Sulfur Cave in Steamboat Springs, Colorado, is full of gases so toxic that a person who enters would pass out after just a few breaths. But that didn't stop David Steinmann of the Denver Museum of Nature & Science. Donning a special respirator, he first explored the cave in 2007. In this extreme environment, devoid of sunlight, Steinmann found clumps of tiny blood-red worms, each one just an inch long and as thin as a pencil lead. Now genetic analysis has confirmed that the worms are a new species that may not be found anywhere else on Earth. These tiny worms could even offer clues to the kinds of life that might be found on other planets.

http://video.nationalgeographic.com/video/news/160603-sulfur-cave-w...

How do caves form?

Put simply, caves form when flowing water slowly dissolves rock over a long time. Specifically, they form within certain geological formations called "karst"—which includes structures made of limestone, marble and dolomite.

Karst is made of tiny fossilized microorganisms, shell fragments and other debris that accumulated over millions of years. Long after they perish, small marine creatures leave behind their "calcerous" shells made of calcium carbonate. Corals are also made of this material, as are other types of fauna with skeletons.

This calcerous sediment builds up into geological structures that are relatively soft. As water trickles down through crevices in the rock, it continuously dissolves the rock to slowly form a cave system.

Unlike much harder igneous rocks (such as granite), calcerous rocks dissolve on contact with water that is naturally acidic. When rain falls from the sky, it picks up carbon dioxide from the atmosphere and soils along the way, which makes it acidic. The more acidic the water, the faster it will erode karst material.

cave formation can become quite complex: the specific composition of the karst, the acidity of the water, the level of drainage and the overall geological setting are all factors that determine what kind of cave will form.

In geology there's a lot of spatial guesswork. Being able to see how deep a cave formation goes is a bit like getting into the deepest layers of a cake, where you may not find the same thing in all directions.

Stalagmites and stalactites

From a research perspective, caves are incredibly valuable because they contain cave deposits (or "speleothems") such as stalagmites and stalactites. These are sometimes spiky things that point up from cave floors, or droop from the ceilings, or form beautiful flowstones.

Cave deposits form as a result of water passing through the cave. Like trees, these contain growth rings (or layers) that can be analyzed. They can also include other chemical signatures the water contained, which can reveal processes that occurred at the time of formation.

While they may not seem like much, we can use these deposits to unravel past secrets about Earth's climate. And since they're a feature of the interaction between rock and water during cave formation, we can basically expect to find them in most caves.

While cave systems are usually stable (shallow caves can in theory collapse and form sinkholes, but this is very rare)—there's always risk. The unexpected geometry of caves means you could find yourself making tricky maneuvers, twisting and swaying in all kinds of uncomfortable manner as you abseil into darkness.

Although the air pressure doesn't change to a dangerous extent as you descend, other gases such as methane, ammonia and hydrogen sulfide can sometimes pool and lead to suffocation risk.