Karst Topography - JPIIjp2hs.org/wp-content/uploads/2016/11/Taylor-Karst-Presentation.pdf · Karst...
Transcript of Karst Topography - JPIIjp2hs.org/wp-content/uploads/2016/11/Taylor-Karst-Presentation.pdf · Karst...
Karst TopographyBy Taylor Pepper
What is Karst?Early on, Karst landscapes look like any other generally flat plane, but with cracks sizeable enough to drain and store water from the constant rainfalls and a top layer of soluble rock like limestone or dolomite
Karst terrain is generally barren, rocky ground lacking in surface streams or rivers with caves, sinkholes, lapies, pepino hills, land bridges, and underground streams/ rivers
One example of Karst landscape is the Tsingy de Ankarana (top image) which shows a “forest” of limestone blades remaining after water dissolved the rest of the Jurassic stone away
Another example is Carlsbad Caverns in New Mexico (bottom image) which is a large system of caves with massive limestone deposits and scattered underground springs
How Are Karst Landscapes Formed?Elements that promote Karst landscapes:
Dense, jointed limestone (or other soluble rock)
near the surface
Moderate to heavy rainfall
Openings to allow good groundwater circulation
The water flowing into the vertical cracks, and
sinkholes, at the surface down to the openings
underground circulate long enough to form cave
systems or underground water channels
Sinkholes are formed by the tops of cave systems
collapsing due to opening so close to the surface
ThermokarstThermokarst- configuration of the land due to the melting of ground
ice in a region with permafrost
The size and nature of the features depend solely on how much ice is
in the area and the nature of that ice
The widespread effects of thermokarst show the region is warming in
temperature, while a localized situation can be due to traffic of some
sort or construction efforts, deforestation, or agriculture
Features created by melting dead glacial ice is not considered
thermokarst
FluviokarstFluviokarst- evidence of tributary surface streams that
lead to stream beds underground where the drainage
occurs
Ex. A normal stream valley that gradually deepens its
channel until it accesses underground dolomite deposits,
which water is lost in the fractures to create underground
cave systems
Surface becomes a "blind valley", or polje, which are long
basins with flat surfaces surrounded by steep cliff sides, or
a "dry valley" where no more channels are created
Floor of valley full of sinkholes and limestone residue
Salt KarstSalt Karst- a solution phenomena that occurs in rock salt
under the effect of groundwater
Rock salt is actually more soluble than the calcite
dissolved in Karst topography, it is impervious because the
solution can only happens on the outside surface
The brine created from the dissolved salt must be carried
away by groundwater in order for more solution to occur
The topographical features are formed depending solely
on the thickness of the rock body
These shallow features can be created on flat landforms
with thick salt crusts by the draining of water down to the
water table
Doline KarstDoline Karst- usually rolling plains with few surface
streams and no valleys
Surface covered by a multitude of sinkholes of different
sizes that can connect to create valley sinks, and this is
caused by the dissolution of the bedrock at fractures,
collapsing cave roofs, or soil loss
An arched void forms and stretches to the surface to
form sinkholes
Pavement KarstPavement Karst- bare carbonate rocks exposed to
weathering
Usually occurs because of glaciation, where ice scrapes
off soil and other materials to expose the bedrock
underneath
Occurs in higher altitudes and alpine areas where
glacial activity is common
The solution also weathering of the dolomite is usually
due to direct rainfall on the rock and meltwater from
snowpacks
Karren, features of Pavement Karst, consists of
solutionally widened joints, small runnels, small
residual pinnacles, and other features
Cone and Tower KarstCone and Tower Karst- thick limestone deposits are
separated by grids of fractures
Common in tropical areas
The solution produces rigid edges of the limestone
towers, which divide them into separate pieces
The water dissolving the edges drains into the
subsurface, preventing the area from becoming a valley
system
Cones are created when the water affecting the deposit
creates a conic shape out of the deposit
In other situations, gorges reach a sort of base level
where it begins widening, allowing the features to stick
out vertically throughout the plain
References1. Encyclopædia Britannica, Inc. "Karst.” Encyclopædia Britannica Online, Web. <https://www.britannica.com/science/karst-geology>.
Accessed 14 Sept. 2016.
2. Maurits & Marjol. “Tsingy de Ankarana.” Flickr, Image. <http://www.wondermondo.com/Madagascar.htm>. Accessed 21 Sept. 2016.
3. National Park Service. “Carlsbad Caverns, NM.” The Physical Environment, Image. <http://www.earthonlinemedia.com/ebooks/tpe_3e/mass_movement_weathering/karst_landscapes.html>. Accessed on 14 Sept. 2016.
4. Encyclopædia Britannica, Inc. “Cross Section of a Cave.” Encyclopædia Britannica Online, Image. <https://www.britannica.com/science/karst-geology>. Accessed 21 Sept. 2016.
5. Encyclopædia Britannica Inc. "Thermokarst.” Encyclopædia Britannica Online, Web. <https://www.britannica.com/science/thermokarst>. Accessed 14 Oct. 2016.
6. Anthony, Katey Walter. “Arctic Lakes.” UAF, Image. <http://news.uaf.edu/arctic_lakes_july2014/>. Accessed 14 Oct. 2016.
7. “Salt Karst.” Tamriel-Rebuilt, Image. <http://tamriel-rebuilt.org/forum/region-deshaan-plains-concepts-discussion>. Accessed 17 Oct. 2016.
8. "Classic Fluviokarst." Cave Archaeology, Image. <http://cavearchaeology.weebly.com/karst-geomorphology.html>. Accessed 17 Oct. 2016.
References Contd.1. Encyclopædia Britannica Inc. "Cave." Encyclopædia Britannica Online, Web.
<https://www.britannica.com/science/cave/Solution-cave-features>. Accessed 17 Oct. 2016.
2. Homer, Lloyd. "Dolines." Science Learning, Image. <http://sciencelearn.org.nz/Contexts/A-Fizzy-Rock/Sci-Media/Images/Dolines>.
Accessed 17 Oct. 2016.
3. Chensiyuan. "Cone Karst." Wikipedia Creative Commons, Image. <http://www.goodearthgraphics.com/virtcave/karst/karst.html>.
Accessed 17 Oct. 2016.
4. "Tower Karst." Environmental Hazards in Karst Landscapes, Image.
<http://people.uwec.edu/jolhm/eh/below/Matt%20Below%20-%20GEOG%20361-home.htm>. Accessed 17 Oct. 2016.
5. Lupin. "Limestone Pavement Above Malham Cove." Wikimedia Commons, Image.
<https://commons.m.wikimedia.org/wiki/File:Limestone_pavement_above_Malham_Cove.jpg#mw-jump-to-license>.