Caves
A brief study of four main types of caves
Compiled by Kella Randolph M. Ed.

What is a cave?
• A cave is a natural opening in the ground
extending beyond the zone of light and large
enough to permit the entry of man. Occurring
in a wide variety of rock types and caused by
widely differing geological processes, caves
range in size from single small rooms to
interconnecting passages many miles long.
The scientific study of caves is called
speleology (from the Greek words spelaion
for cave and logos for study). It is a composite
science based on geology, hydrology, biology,
and archaeology, and thus holds special
interest for earth scientists of the U.S.
Geological Survey.
• Left: View of a passage walkway in Wind Cave
• 3dparks.wr.usgs.gov

Types of Caves
A simple classification of caves includes four main types and several other relatively less
important types.
• Solution caves are formed in carbonate and sulfate rocks such as limestone, dolomite, marble,
and gypsum by the action of slowly moving ground water that dissolves the rock to form tunnels,
irregular passages, and even large caverns along joints and bedding planes. Most of the caves in
the world-as well as the largest-are of this type.
• lava caves are tunnels or tubes in lava formed when the outer surface of a lava flow cools and
hardens while the molten lava within continues to flow and eventually drains out through the
newly formed tube.
• Sea caves are formed by the constant action of waves which attacks the weaker portions of
rocks lining the shores of oceans and large lakes. Such caves testify to the enormous pressures
exerted by waves and to the corrosive power of wave-carried sand and gravel.
• Glacier caves are formed by melt water which excavates drainage tunnels through the ice. Of
entirely different origin and not to be included in the category of glacier caves are so-called "ice
caves," which usually are either solution caves or lava caves within which ice forms and persists
through all or most of the year.
• USGS http://geomaps.wr.usgs.gov/parks/cave/#what

Solution Cave
Ground water dissolves certain
rocks made of limestone, dolomite
and gypsum, creating tunnels,
passages and caverns below the
surface of the ground.
Cave Geology | Missouri State Parks Less
600 x 424 70.5KB
mostateparks.com

Solution Cave
The action of slowly moving ground
water that dissolves the rock to form
tunnels, irregular passages, and even
large caverns along joints and bedding
planes. Most of the caves in the world-
as well as the largest-are of this type.
Domica Cave is the most known and
longest cave of the Slovak Karst National
Park.
Domica Cave
http://www.ssj.sk/en/jaskyna/7-domica-cave
Description Domica Cave 22.jpg
commons.wikimedia.org 3456 x
23044169.4KB

Lava caves
Lava caves are tunnels or
tubes in lava formed when
the outer surface of a lava
flow cools and hardens while
the molten lava within
continues to flow and
eventually drains out through
the newly formed tube.
http://geomaps.wr.usgs.gov/parks/cave/#what
www.flickr.com

Glacier Caves
Glacier caves are formed by melt
water which excavates drainage
tunnels through the ice. Of entirely
different origin and not to be included
in the category of glacier caves are so-
called "ice caves," which usually are
either solution caves or lava caves
within which ice forms and persists
through all or most of the year.
Top: blue ice cave
http://www.123rf.com/search.php?word=glacie
r+caves&imgtype=&Submit=+&t_word=&t_lang
=en&orderby=0&sti=mgvkuqmnwtkdsflmum|&
mediapopup=6070282
Antarctic Glacier with cavities.

Karst Topography
• The degree of development of karst landforms varies greatly from region to region. Large
drainage systems in karst areas are likely to have both fluvial (surface) and karst (underground)
drainage components. As stated in the introduction, the term karst describes a distinctive
topography that indicates dissolution of underlying rocks by surface water or ground water.
• Water falls as rain or snow and soaks into the soil. The water becomes weakly acidic because it
reacts chemically with carbon dioxide that occurs naturally in the atmosphere and the soil. This
acid is named carbonic acid and is the same compound that makes carbonated beverages taste
tangy. Rainwater seeps downward through the soil and through fractures in the rock responding
to the force of gravity. The carbonic acid in the moving ground water dissolves the bedrock along
the surfaces of joints, fractures and bedding planes, eventually forming cave passages and
caverns.
• Limestone is a sedimentary rock consisting primarily of calcium carbonate in the form of the
mineral calcite. Rainwater dissolves the limestone by the following reaction: Calcite + Carbonic
acid = Calcium ions dissolved in ground water + Bicarbonate ions dissolved in ground water.
http://www.nature.nps.gov/geology/usgsnps/cave/karst.html

Permeable Rock
Cracks and joints that interconnect in the soil
and bedrock allow the water to reach a zone
below the surface of the land where all the
fractures and void spaces are completely filled
(also known as saturated) with water. This
water-rich zone is called the saturated zone and
its upper surface is called the water table. The
volume of void space (space filled with air or
water) in soil or bedrock is termed porosity. The
larger the proportion of voids in a given volume
of soil or rock the greater the porosity. When
these voids are interconnected, water or air (or
other fluids) can migrate from void to void. Thus
the soil or bedrock is said to be permeable
because fluids (air and water) can easily move
through them. Permeable bedrock makes a
good aquifer, a rock layer that holds and
conducts water. If the ground water that flows
through the underlying permeable bedrock is
acidic and the bedrock is soluble, a distinctive
type of topography, karst topography, can be
created.
http://geomaps.wr.usgs.gov/parks/cave/#what

What’s in it for Me?
Knowing where karst features are located
could help city and town planners, as well as
individual landowners, to make decisions on
where to build houses and other structures.
This information could save cities thousand
of dollars in repairs to buildings that are built
on unstable karst terrain.
Karst springs supply drinking water to
millions of people. Knowledge of karst terrain
and the movement of water in underground
drainage systems is important for
maintaining good quality and safe drinking
water. Pollution of ground water is a major
problem in karst terrain.
http://www.nature.nps.gov/geology/usgsnps
/cave/karst.html
www.publicdomainphotos.com

Sea Caves
Sea caves are formed by the constant
action of waves which attacks the
weaker portions of rocks lining the
shores of oceans and large lakes. Wave
action compresses air and exerts
pressure in the cracks of rocks. After
repeated crashes of waves. Water
surges into cracks, joints and faults in
the rock, causing pressure. Retreating
water releases pressure and drags
broken rock particles out to sea.
Such caves testify to the enormous
pressures exerted by waves and to the
corrosive power of wave-carried sand
and gravel.
Mourtos Sea Cave on Greek coast seen from
sea.
http://www.123rf.com/photo_2837168_mourtos-sea-cave-
on-greek-coast-seen-from-sea.html?pdetail=1

Sea Cave Formation
Photos from The World's 16 Most Incredible
Sea Caves Credit: Flickr/Daniel Gillaspia

Should we live there?
Human settlement in the area is
likely to collapse into the sea over
time, as the caves eventually are
eroded enough to collapse the rock
above, leaving a gap between what
was once the side walls of the cave.
Surface Subsidence and Collapse. ...
Some sinkholes form when the roofs
of caves collapse, ... Building cities in
such areas aggravates the problem
for several reasons.
ww.tulane.edu/~sanelson/Natural_Disasters/su
bsidence.htm
Gallery.nen.gov.uk

Education Resources
• USGS Geology of Caves
• http://www.nature.nps.gov/geology/usgsnps/cave/cave.html
• and USGS Geology in the Parks
http://geomaps.wr.usgs.gov/parks/cave/#what
• Karst Topography Computer animations and paper model (HTML),
(PDF)
USGShttp://www.nature.nps.gov/geology/usgsnps/cave/karst.html
• Photos credited on slides