Earth
Revealed: Groundwater movie. Courtesy of Anneberg
Media, URL <http://www.learner.org/resources/series78.html>. Requires
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Groundwater - Text: Bloom, Arthur, 2004, Geomorphology: Chapter
8-Karst and Speleology
- Jones and Jones-Lab Manual, Chapter 9-Groundwater and Groundwater-Influenced
Landscapes
|
Terms: Speology, epigenic, thermokarst,
hypogenic karst, limestone, carbonate, dolomite, carbonic acid, corrosion,
corrasion, porosity, permeability, hydraulic gradient, groundwater,
humus, aquifer, spring, dissapearing stream, hydraulic gradient, karst,
thermokarst, solution, sinkhole (doline), tower karst, blind valley,
polje, pocket valley, cone karst, uvula, phytokarst |
Definition of karst:
Karst terrain has distinctive characteristics of relief
and drainage arising from the solution of soluble bedrock by natural waters.
Features of karst terrains may include a variety of sinkholes, solution
valleys, underground rivers, caverns, disappearing streams, towers, and
distinctive conical hills. Although most karst is developed in limestone
(CaCO3) or dolomite (MgCaCO3) it also forms in soluble
evaporite deposits. Karst-like features developed in permafrost by
the melting ice is called thermokarst. Most karst
is epigenic, created by carbonic acid contained in shallow-circulating
meteoric waters. However, some karst cave systems, such as Carlsbad
Caverns in New Mexico, are attributed to sulfuric acid associated with
deep hydrocabon deposits. This type of karst is refered to a hypogenic karst.
Terms:
- Limestone: A sedimentary rock composed of the mineral calcite. Limestones
are typically deposited in shallow warm water marine environments
and arid - semiarid inlands seas and lakes.
- Corrosion: chemical erosion of rock. Remember that erosion
involves the weathering and removal or rock material.
- Corrasion: mechanical erosion of rock by a moving agent (e.g water, ice,
etc.)
- Classic Glossary: Cave
and Karst Terminology by J.N. Jennings
1. Soluble rock at or near the surface (limestone, dolomite, rock
salt, gypsum, etc.). Karst is typically associated with carbonates.
2. Dense rock (little interstitial porosity) which is highly jointed. Solution
is facilitated by the concentration of groundwater along joints. If a rock
is too porous flow is not locally concentrated and karst development is inhibited.
Chalk develops poor karst due to its high porosity.
3. High hydraulic gradient (h/l) produced
by steep topography or entrenched rivers. Moving water corrodes much faster
than standing water. The velocity of groundwater is determined by the following
equation: V = (K/p)(h/l) where K is the coefficent of permeability, P is
effective porosity, h is the head, and l is the length of the groundwater
flow path. All other factor equal the steeper the gradient the fast
the flow. Therefore, a high hydraulic gradient reduces the residence
time thereby inhibiting the development of equilibrium between the rock and
and surrounding waters.
4. high rainfall: More
water more solution.
5. high biological activity: As discussed
in the weathering lecture, plants, algae,
and lichen not only secrete acids but are responsible for increasing the
amount of carbonic acid entering the groundwater system. Blue-green algae
can produce a surface karst characterized pitting and a sharp-edged spongy
lattice of ridges and pinnacles. This epilithic plant-generated karst is
called phytokarst.
- humus: Decayed organic material increases the acidity of
the water by increasing the CO2 content in soils. Humus
also releases organic acids.
- Algae: produces phytokarst (an intricately pitted, sharp-edges
topography formed by the solution of limestones by acid solvents generated
by algae)
- Organic waste: Phosphate-rich guano produced by birds
and bats strongly corrode limestone. Rock phosphate produced
by the reaction of guano and limestone fills karst cavities, in some
cases to a depth of 20 m producing commercial deposits.
6. Warm Temperatures
- High temperature: Increases biochemical activity so that more
CO2 and organic acids are formed
- Low temperature: Cold water has a higher potential of becoming
more acid
- Example: 10°C water dissolves 2x more CO2 than
30° water
- 0°C water dissolves 3x more CO2 than 30° water
- However, in cold regions dissolution is actually
less because
- there is less CO2 available to dissolve in water
due to low biochemical activity,
- in permafrost regions the water is frozen; acid water is
restricted to the upper active layer, and
- cold water is more viscous and flow is slower.
7. Pressure:
- Water under pressure can dissolve more CO2 and
therefore hold more CaCO3 in solution
- Release of pressure will result in
deposition of CaCO3 from water previously under
hydraulic pressure (e.g. travertine)
- Turbulence may also result in deposition
(e.g.tufa deposits in rivers)
8. Mixing of carbonate waters (fig.1)
- Because of the nonlinear relationship between
Ca++ and CO2, an under-saturated, aggressive body
of water is produced by the mixing of two saturated water bodies.
|
Figure 1. Two dissimilar water masses that are saturated relative
to CaCO3 are mixed producing an undersaturated mixture which
can more aggresively attack carbonate. |
Polar Regions: Karst is poorly
developed
- Reasons:
- Low rainfall and short runoff season
- Limited infiltration in permafrost regions
- Cold temperatures result in low biochemical activity.
- Even though ground water may have large amounts of CO2 it
is not particularly aggressive. Why?
Cold Humid Mid Latitudes: Well
developed karst characterized by limestone sinks and closed depressions
- Reasons:
- Greater precipitation
- Infiltration is uninhibited
- Greater biochemical activity
- More CO2
- more organic acids
- Karst in the US: Inside
the Earth, NPS Cave & Karst Programs Newsletter
(USGS NPS)
Subhumid and semiarid steppe and savanna
grasslands: Little to no karst development
- Reasons:
- Very low precipitation
- During hot dry seasons groundwater tends to move upward and
deposit carbonate rather than dissolve it. (Caliche/duricrust:
hard crust on arid soils formed by the precipitation of CaCO3 )
- **Limestone in arid regions forms ridges and cliffs rivaling
sandstone in its stability.
Tropical Rainforests: Well
developed karst characterized by residual hills. Region where karst is
best developed.
 |
| Figure 2. Steep karst towers in Guilin China. (source unknown). |
- Reasons:
- Very high rainfall
- Warm temperatures and thick vegetation results in high concentration
(partial pressure) of organic acids and CO2
- Groundwater flows through the ground in large quantities and
is very aggressive
Other controlling factors:
- Besides climate and lithology, other factors which strongly influence
the nature of karst landscapes are:
- Base-level fluctuations: caused by tectonic
activity or changes in sea level
- (i.e. eustatic lowering during glaciation)
- Structure: solution exploits fracture
systems and other planes of weakness that are structurally
controlled
- Stratigraphy: thickness of limestone and
permeability of adjacent units
- Geologic history (is the landscape active,
relict, or exhumed?)
Microforms: Grikes, flutes (rillenkarren),
solution runnels, solution pits, etc. are formed by runoff on bare surfaces.
Karst Drainage: Most
drainage is subterranean with very few continuous surface streams. Surface
drainage patterns tend to be centripital.
- Unlike most fluvial terrains, which are progressively eroded downward
towards baselevel, karst terrains are eroded
- upward by subsurface abstraction into subterranean drainages
and
- by lateral planation by streams already adjusted to base
level
Dolines/Sinkholes
Dolines, or sinkholes are enclosed depressions
created solution.
solution doline: Funnel-shaped doline
formed by the progressive subsidences as solution progresses
along a joint or joint intersection. Regolith drapes the floor
of the doline.
Subsidence doline: Similar to
solution doline but overlying soil has washed into a subsuface
cave system.
collapsed doline: Steep-sided
sink formed by collapse into a subterranean cavity. An underground
cavern forms. Eventually the overlying rock is longer collapses. |
Figure 3. Solution doline. From Tihansky (1999) |
 |
Figure 4. Subsidence doline. |
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|
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Figure 5. Collapsed doline. Source: USGS |
Swallow hole (ponors): Limestone sink into which
a stream disappears.
Subjacent karst collapse dolines: Overlying non-carbonate
rock collapsed into a limestone cavern |
|
Factors conducive to sinkhole formation:
- flat land: doline formation is inversely proportional to slope
as a result of lower infiltration rates and greater runoff rates.
- Massive well-jointed limestone
- C-rich vegetative cover - decaying vegetation provides CO2 and
organic acids
Uvalas (Compound sinkholes): Consist of a series of intersecting
dolines
Karst valleys
- Blind valley: Well developed valley lacking a stream. Part
of an intricate drainage system which is also dry.
- Allogenic Valley (formed or originating elsewhere):
Deep gorge-like valley formed as a stream flows from a nonkarstic region
into a karstic region.
- Dry valley: Well developed valley lacking a stream.
Commonly part of an intricate drainage systems which is also dry. Forms
when a surface-water drainage system becomes diverted underground.
- Theories on the formation of dry valleys:
- Superposition theory
- Drainage system develops on less permeable rock
overlying limestone
- Drainage system is superimposed on limestone terrane
- Subterranean drainage forms and valley becomes
dry
- Base level change
- Drainage developed with groundwater table close
to surface
- Uplift, lowering of sea level, or
local base level by erosion results
in lowering of gw table and subterranean
migration of surface water
- Pocket valley: Valley headed by a large spring
- Poljes: Large valleys or lakes with broad valley floors
which are oriented along a tectonic trend. Paninsko
polje, Slovenia
- Genetic sequence might be: doline--uvala--poljes?
Towers and Cones: characteristic
of tropical karst
- Polygonal karst (cockpit karst): Egg-carton-type topography
developed by extensive solution along intersecting joints
- Cones, mogotes, & towers: Isolated carbonate
hills on a alluvial plain. The plain is either on impermeable bedrock
rock or on limestone that has been lowered close to base level.
- Images
of Puerto Ricos tropical karst
- Tower
Karst Halong Bay, Vietnam, images by Sharon Johnson, see also Guilian
Photo Album Chinahighlights.com
How are Seti(Search for ExtraTerrestrial Intelligence) and tropical karst
related? The
Big Dish -located in a cockpit
 |
 |
 |
 |
| a. Sinkholes @ Interlachen Lake FL |
b. Karst tower, Guilin, SW China |
c. Cone and cockpit karst, Puerto Rico |
d. Mogotes, Puerto Rico |
| Figure 6 a-e. Google
Earth images of karst landscapes from around the world. Click on
each image to enlarge. |
Online Quizzes
| Companion Website for Physical Geography: A Landscape
Appreciation, Chapter
17: Solution Processes and Karst Topography, 8th Ed,:Tom L. McKnight
and Darrel Hess, Michael Ritter Website author URL: http://wps.prenhall.com/esm_mcknight_physgeo_8/0,9340,1445831-,00.html |
Classic Dinaric Karst-Slovenia and Montenegro
(Yugoslavia)
World Karst
- Edward Frank, John Mylroie, Joseph Troester, E. Calvin Alexander,
Jr. and James Carew-Karst Development
and Speleogenesis, Isla de Mona, Puerto Rico. Journal
of Cave and Karst Studies 60(2):73-83.
- Karst
of Gulian, Pitre Migon, International Association of Geomorphologists
http://www.geomorph.org/sp/gal/pmigon/gui.html -
classic tower karst
- Karst,
Jenolan Caves (Australia), URL: http://www.jenolancaves.org.au/karst.html
Karst in the United States
- The
National Karst Map http://www2.nature.nps.gov/nckri/map/index.html > Karst
links by state
- USGS: The
Geology of Caves, Modified from: W. E. Davies and I. M. Morgan
US Geological Survey, URL: http://geology.wr.usgs.gov/docs/usgsnps/cave/index.html
- NASA GFS: Karst
Landforms and Lakes
- Views
of the National Parks-Cave Karst, National Park Service - Natural
Resource Program Center, URL: http://www2.nature.nps.gov/views/Index_caveskarst.htm#
- Learn
about Karst, Karst Waters Institute, URL: http://www.karstwaters.org/kwitour/whatiskarst.htm
- Tihansky, A.B., 1999, Sinkholes,
west-central Florida, in Galloway, Devin, Jones D.R., Ingebritsen,
S.E., eds., Land subsidence in the United States: U.S. Geological
Survey Circular 1182, p. 121-140
Karst Formation
- Dreybrodt, W. and Gabrovsek, F. 2003. Basic
processes and mechanisms governing the evolution of karst.
/ Speleogenesis and Evolution of Karst Aquifers 1 (1), www.speleogenesis.info
, 26 pages, re-published from: Gabrovsek, F. (Ed.), 2002. Evolution
of karst: from prekarst to cessation. Postojna-Ljubljana: Zalozba
ZRC. 115-154. URL: http://www.speleogenesis.info/archive/publication.php?PubID=4&Type=publication
- Ford, D.C. 2003. Perspectives
in karst hydrogeology and cavern genesis. / Speleogenesis
and Evolution of Karst Aquifers 1 (1), www.speleogenesis.info
, 12 pages, re-published from: Palmer, A.N., Palmer, M.V., and
Sasowsky, I.D. (eds.), 1999. Karst Modeling: Special Publication
5, The Karst Waters Institute, Charles Town, West Virginia (USA),
17-29. URL http://www.speleogenesis.info/archive/publication.php?PubID=1&Type=publication
- Lugo, Ariel E.; Castro, Leopoldo Miranda; Vale, Abel; López,
Tania del Mar; Prieto, Enrique Hernández; Martinó, Andrés
García; Rolón, Alberto R. Puente; Tossas, Adrianne G.;
McFarlane, Donald A.; Miller, Tom; Rodríguez, Armando; Lundberg,
Joyce; Thomlinson, John; Colón, José; Schellekens,
Johannes H.; Ramos, Olga; Helmer, Eileen 2001. Puerto
Rican Karst-A Vital Resource United States Department of Agriculture
Forest Service Gen. Tech. Report WO-65. URL: http://www.treesearch.fs.fed.us/pubs/2864
- Taylor, Michael Ray, 2006, Subterranean
life thrives deep in water system: Researchers find that 'badwater'
in Edwards Aquifer is home to an array of life-forms, Houston
Chronicle - hypogenic karst
- Geology
and geomorphology of limestone pavements, Limestone pavement
action group, URL: http://www.limestone-pavements.org.uk/geology.shtml
Hazards
- Living
on Karst: A Reference Guide for Landowners in Limestone Regions Produced
by the Cave Conservancy of the Virginias, URL: http://www.dcr.virginia.gov/dnh/livingonkarst.htm
Exercise
Mammoth Caves Kentucky (USGS
shaded Relief map). Reveiw the description and stratigraphy
from my Mammoth Caves
National Parks site. Click on the image to the right enlarge.
Print it and complete the following exercises:
A. Locate and label examples of the following features.
- sink hole
- compound sink hole (uvala)
- karst valley
- blind valley
- Region of subajacent karst
B. Draw the drainage network as indicated by the valleys. Can
you define the direction of regional drainage? Explain.
|
 |
Bloom, Arthur. 2004, Geomorphology, A systematic analysis of Late Cenozoic
Landforms, (4th edition): Waveland
Press Inc., Longe Grove , IL 482 p.
Barton, Hazel and Luizer Frederick, 2005, Microbial
metabolic structure in a sulfidic cave hot spring: Potential mechanisms
of biospeleogenesis. Journal of Cave and
Karst Studies, v. 67, no. 1, p. 28-38.
Chorley, R.J., Schumm, S.A., Sugden, D.E., 1984, Geomorphology: Methuen
and Co. Ltd., London, 605 p.
Easterbrook, D.L., , 1992, Surface Processes and Landforms, Prentice Hall,
Inc., Upper Saddle River, NJ, 546 p.
*Jennings, J.N., 1971, Karst: MIT Press, Cambridge, MA, 252 p.Ritter,
D.F., Kochel, C.R., and Miller, J.R., Process Geomorphology (3rd Edition):
Wm.C. Brown Publishers, Dubuque, IA, 544 p.
Hill, Carol A., 2000, Overview
of the geologic history of cave development in the Guadalupe Mountains,
New Mexico. Journal of Cave and Karst Studies 62(2):60-7
Summerfield, M.A., 1991, Global Geomorphology: John Wiley and Sons, New
York, NY, 536 p.*Trudgill, S., 1985, Limestone geomorphology: Longman,
London, 196 p.
Tihansky, A.B., 1999, Sinkholes,
west-central Florida, in Galloway, Devin, Jones D.R., Ingebritsen,
S.E., eds., Land subsidence
in the United States: U.S. Geological Survey Circular 1182, p. 121-140
USGS, Sinkholes,
Water Science for Schools http://ga.water.usgs.gov/edu/sinkholes.html
Lindley
Hanson/Department
of Geological Sciences/Salem
State College/Geomorphology/GeoIndex/QkRef
