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Cave
Cave  
Cave
Cave  
QUESTION: Dear Keith

http://en.wikipedia.org/wiki/Cave
http://en.wikipedia.org/wiki/Elephanta_Caves
http://en.wikipedia.org/wiki/Caving
http://en.wikipedia.org/wiki/Speleology
http://www.uis-speleo.org
http://www.caves.org/
http://www.nsscds.org/?q=taxonomy/term/47
http://www.britannica.com/EBchecked/topic/559211/speleology

Are Caves always Closed Structures ?. i.e. The Entry and Exit Points are always the same. There can be multiple entry points to enter the cave structure but the entry points will be always the exit points ?. Exit point i mean is coming out of the cave structure. For example in a Theater hall the entry (To enter the Cinema Hall) and exit (To exit the Cinema Hall) points may be different.

Will there be any specific advantages if exit points are created /constructed (only if exit points do not exist) within the cave
structures ?

Awaiting your reply,

Thanks & Regards,
Prashant S Akerkar

ANSWER: Prashant:

I guess the terms are relative.  One man's entrance may be another man's exit.

For instance.  In Jamaica, there is a cave near Negril.  The entrance is across the road from a famous bar, named Ricks Cafe.  The cave is owned by the woman who owns the property on which the entrance sits, but down below, the cave opens to the ocean.  She owns the cave, the bar under which it sits does not.  Maybe a court decided the fact, or common law did because she owned and developed the cave and the bar did not.  

So what constitutes an entrance?  An entrance is simply formed by erosion causing an intersection of the topographic surface with the underlying void (the cave) creating a way to enter the cave.  There can be numerous entrances depending the configuration of the topography and the timing of the breach of the cave.

Yes, caves or caverns are closed stuctures at one point in their development, in so far as we have not discovered any entrances or exits.  The formation of most large caves is dissolution of limestone by water action, be it ocean or ground water.  The rock is usually submerged below the water table or water percolates through fractures in the rock enlarging them and eventually they grow larger and larger.  If the path through which the water enters, fractures be they small or large, can be considered entrances, depends on how large they are, or how small the man is.  The exception to this are lava tubes, which I would suppose you could say are formed as tunnels with an entrance (in the magma chamber of a volcano, or a magma vent) and exit (where the magma exits) since they form by the movement of non viscous silicic magma.  

---------- FOLLOW-UP ----------

QUESTION: Dear Keith

Thank you.

http://en.wikipedia.org/wiki/Mineral

Can Caves exploration help in identifying potential sources of Minerals
for Mankind ?.

Awaiting your reply,

Thanks & Regards,
Prashant S Akerkar

Answer
Prashant:

Yes they can.  While most karst related caves do not hold much potential for commercial minerals, other forms of caves do.  Recently caves in Mexico were discovered that had once been filled with hydrothermal fluids.  That is, they were filled with hot fluids containing dissolved elements or ions.  These dissolved ions tend to gravitate to each other to form crystal structures in a know sequence of formation...certain common minerals form in sequence using up the available ions, until only the odd more rare ions remain and they begin to form rare minerals better know as precious gems.

The longer the aqueous hydrothermal solution stays hot the larger the mineral crystals can grow.  In this case they were huge, on the order of 10 meters in length.

http://news.nationalgeographic.com/news/2007/04/photogalleries/giant-crystals-ca

http://www.mineraltown.com/reports/giant_crystals/giant_selenite_crystals.php

http://www.virginmedia.com/science-nature/natural-world/weirdest-places-on-earth

The cave in question has since been reflooded and teh temperatures were very high and exploration was very dangerous due to the high temperatures.

Other caves, have been found in rock deposits called pegmatites.  These are not so much as caves, as voids.  They occur in granite batholiths formed deep in the earth.  Pockets of the last portions of liquid and steam from the cooling granite magma collect like voids in a pot of hot gruel or cooked oatmeal.  The pocket fills with large crystals of semi precious gems, and eventually millions of years later when the granite gets near the surface of the earth through uplifting or by erosion, the pocket gets breached.  These are sometimes found in granite quarries when they cut into the granite and find these huge voids filled with crystals.  Kind of like gigantic geodes.  

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Keith Patton

Expertise

I can answer questions concerning physical and historical geology, environmental geology/hydrology, environmental consulting, remote sensing/aerial photo interpretation, G&G computer applications, petroleum exploration, drilling, geochemistry, geochemical and microbiological prospecting, 3D reservoir modeling, computer mapping and drilling.I am not a geophysicist.

Experience

I have 24 years experience split between the petroleum and environmental industries. I have served as an expert witness in remote sensing, developmental geologist, exploration geologist, enviromental project manager, and subject matter expert in geology and geophysical software development.

Organizations
American Association of Petroleum Geologists
American Association of Photogrammetrists and Remote Sensing

Education/Credentials
Bachelor and Master of Science
Registered Geologist in State of Texas

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