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Roger Weller, geology instructor

by Daniel Spooner
Physical Geology
Fall 2009


Caves and the Treasures They Hold.

            Caves or caverns as they are sometimes called come in many shapes sizes and forms, the 5 most common being, Solutional, primary, sea, fracture, and glacier.   Recently confirmed however, are caves formed by sulfuric acid, this is significant because a cave formed by sulfuric acid is created from the bottom up, rather than from the top down.   Defined as a naturally occurring subterranean void, caves are found all over the world and few people realize just how many economical purposes caves serve.  Examples of the services caves provide include: organic fertilizer, birdsí nests, medicinal compounds, and varied aesthetic mineral formations. 

Types of caves

Solutional caves:

The most common type of caves, Solutional caves, form by carbonic acid dissolution.  When rain falls to the earth, minute quantities of carbon dioxide combine with the water creating a slow acting but powerful acid known as carbonic acid (carbonated water).  When carbonic acid seeps into the ground, it acts as any liquid does following the path of least resistance, most commonly cracks.  Once the acid is in a rocks natural crack, it begins to dissolve the surrounding rock, eventually leaving behind a cavity.


(Deer cave, Mulu National Park)


Primary caves:

Primary caves are caves formed at the same time as the rock surrounding it.  The most common and well known are lava tubes.  Lava tubes are formed when lava flowing down a hill solidifies on the surface while staying liquid underneath.  Then, the lava drains out as no more lava travels down this channel, leaving behind a round tunnel.


Thurston Lava Tube - Hawaii 

... lava tube in Hawaii 

Sea caves

Sea caves, or littoral caves as they are sometimes called, are caves formed by the pounding of the oceans waves.  When waves hit a cliff, the constant pounding of the water and whatever else picked up by the waves slowly erodes the base away. But, when waves hit a cliff with faults, dykes, or bedding plane contacts (where layers of soil converge), the weakened cliff side is rapidly eroded away creating a cavity. 

Sea Cave 

Sea Cave 

Sea Cave - Picture - MSN ... 

Fracture caves:

Fracture caves are formed when layers of water soluble rock, such as gypsum, halite (salt), and sylvite, come into contact with water.  Once these rocks are dissolved, they are carried away leaving a cavity behind.  This differs from Solutional caves in that it is water which creates a cavity, rather than carbonic acid.

Salt Caves provides an ideal ... 


Glacier caves:

Glacier caves are formed when a large block of ice (a glacier in most  instances), slowly begins to melt.  As the ice melts, it creates a channel in which to flow.  As more and more ice melts it enlarges the cavity sometimes to massive proportions.  However, as it is made of ice, glacier caves are very short lived and subject to sudden collapse and re-freezing.

Exit Glacier Cave 

... Glacier Cave, Alaska

... -Josepth-glacier-cave.jpg 

Sulfuric acid:

Caves form by sulfuric acid, when hydrogen sulfide leaks over from adjacent oil deposits dissolving limestone and depositing gypsum.  The best known example of this is Lechuguilla cave in Carlsbad New Mexico. The acid rises from below as a gas, dissolving rock and creating a cavern from the bottom up, while depositing spectacular gypsum formations.

 Lecuguilla cave



Economical products of caves

Birdsí nests:

Living in many caves with wide openings above ground, cave swallows are a common cave sight.   When it is time for cave swallows to lay their eggs, they will use their saliva to construct a bowl shaped nest.  When swallows nest however, hundreds of people climb to the top of ladders (or even just a rope) to collect these delicacies, turning them into birds nest soup (common delicacy eaten in China). This is very dangerous, for the nests are always made at ceiling level, sometimes over a hundred feet up, with many people dying each year.


 Bird's Nest is actually part ...

Nest collecting is skilled ... 


Another common commodity collected in caves is guano (bat excrement).  When a large colony of bats live in a cave, (bat colonies can number in the millions) large quantities of guano builds up below.  Being very high in phosphorus and nitrogen, guano is harvested every year for use in fertilizers and gunpowder.  Yearly, thousands of pounds of bat guano are mined out of caves, packaged, and shipped all over the world.  Guano is so valuable in fact, that in 1879 a war broke out over guano harvesting (


... Guano Fertilizer Products 

Measuring guano Kate Leary ... 

Medicinal compounds:

Over the course of the past decade, scientists have been studying micro organisms called Chemolithoautotroph found only in caves formed by sulfuric acid.  These micro organisms are believed to have medicinal qualities beneficial to humans and are being experimented with.  Unfortunately, the results of their research have not been published.  (Couldnít find any pictures)


Of all the commodities found in caves however, nothing could compare to the beauty of mineral formations.  Forming in diverse ways, there are many types of mineral formations.  The most common of them are: stalactites, stalagmites, soda straws, flow stone, cave pearls columns and helictites.


... Virtual Cave: Salt Caves 



File:Stalagmites Carlsbad Caverns.jpg 



Works cited