how does water help create features of karst topography?
476271
chemical erosion (dissolving elements from the rocks) deepen the cracks between the rocks creating the pavement effect
444036
Water is essential to life, so any people, like wandering tribes, are likely to start to congregate round water sources. Civilisations then can start to grow.
601427
The temperature reduced in proportion with the height of the hill. More the height less is the temperature. The clouds around the hills make it less hot.The flow of cold water, waterfalls, cool breeze add to the chillness.  The shade of the trees reduces the heat. The chillness cools the clouds to pour local rain.  \nThe passing clouds are intercepted by clouds and made to shower more rain.\n  The slope of the hills absorb lesser heat received over a larger area  of the slop through the vertical rays during the high noon time.  The slanting rays with less heat does not reach most of the landscap because of the hilly shape.
643686
It would make water (H2O).
423195
if you drain the ocean you will see mountains, hills, if you fill it back agains you only see their tip, islands.. made erosions, volcanic eruptions, and so on..
165216
Karst!       At least this is the terminology for the type of landscape created by dissolution of limestone, dolomite, gypsum and rarely quartzite. This is the landscape that contains caves, sinkholes, and  dolines.  \n\nThe process is initiated when rain water picks up carbon dioxide in the atmosphere and then picks up even more carbon dioxide as it seeps through soil. Soil often has a carbon dioxide content as high as ten percent so the water may become very acidic, since carbon dioxide combines with water to form carbonic acid.  As the water permeates downward it encounters bedrock. In limestone this bedrock is often fractured and where the water begins to penetrate the rock the carbonic acid will dissolve the limestone, which is calcium carbonate. These fractures will gradually enlarge creating an irregular zone where the soil contacts the bedrock. If the carbonic acid content of the water is high enough, or its penetration rate is fast enough, it will sink into the rock until it hits some sort of a barrier and there it will begin to dissolve away rock. This will eventually become a cave.  Other types of landforms that will develop are sink holes. Sink holes are large pits that form under the soil surface, sometimes by cave collapse, and sometimes just by dissolution. Some areas of the world are dominated by sinkholes, like parts of Puerto Rico and Jamaica's cockpit country. \n\nOther caves that have formed by this process are Mammoth Cave in Kentucky, USA, which is the worlds longest cave. Mammoth Cave is has about 367 miles in length that have been mapped so far, and mapping continues. Another famous cave is Carlsbad Caverns in New Mexico. Carlsbad Caverns was formed by a different type of dissolution when groundwater mixed with sulphur compounds, possibly during petroleum generation or migration, and formed sulphuric acid which is believed to have moved upwards into the ancient Capitan reef rock and dissolved enormous cave passages. Another type of cave forms where different types of groundwater such as saltwater and freshwater mix together in the subsurface. These are called mixing zone caves and they can form at great depths where the reaction between the two solutions creates a potential for dissolution of limestone. \n\nThe Arabika Massif, Western Massif has recently been mapped as the world's deepest cave at –2080m (6824 ft). The Optimisticeskaja in Ukraine is the world's third longest cave and the world's longest gypsum cave at 133 miles. \nhttp://www.pipeline.com/~caverbob/wlong.htm\n\nIn Brazil there is a cave formed by dissolution of quartzite, the Caverna do Centenário and I believe there are some examples of this in Venezuela as well. \nhttp://www.showcaves.com/english/br/caves/Centenario.html\n\nKarst landscapes tend to be some of the poorest in the world because they are difficult to farm. Other problems associated with karst are collapse of sinkholes, such as those that happen occasionally in Florida, taking houses, cars,and everything else down into the hole. Contamination of ground water is a difficult problem in karst areas because the spill of a contaminant can quickly move through a complex underground drainage system in ways that are difficult to predict unless there has been considerable dye tracing of the karst system. One fear of karst scientists around Mammoth Cave is that a spill of a dangerous material on the nearby interstate could contaminate large parts of the cave system within hours or days. \n\nAs for other less dramatic effects of bedrock dissolution, most rainwater does pick up some rock as it percolates downward toward the water table. Most often this solute ends up in the groundwater and is the reason some well water is described as 'hard' water since it has a taste that is given to it by the dissolved minerals. In most areas this dissolution is so insignificant that it does little to change the land surface.
172827
There are a couple ways. Hot spots can build up islands through volcanic activity, like Hawaii. Some islands can be created by subduction volcanism (Japan). Other islands can be uplifted at convergent or possibly transverse plate boundaries.\n\nIslands can also be created by erosion and inundation, as in a case of sea level rise where the water covers low lying areas while higher areas get "separated" from the land by water (St. Lawrence Island in Alaska). Glaciers can scour channels around large land masses, then recede and the channels can become filled with water to surround the land masses and make them islands. Manhattan Island was actually created by a continental glacier pushing a bunch of sediment out into the ocean and then receeding (it is a moraine).\n\nSome islands can be created purely by sediment deposition, such as those at the mouths of deltas. \n\nScleractinean coral will also form islands (atolls) even as the land around them recedes because they require sunlight to live. Coastal erosion is also known to produce offshore bars which, if big enough, can be vegetated and become islands.\n\nRivers can also meander around bits of land on the floodplain and cut them off from the rest of the earth, forming islands.
847353
I believe the classic way of showing the effects of acid rain is to use lime stone corrosion. Test the possibilities using a piece of limestone (chalk or similar), three different petrie dishes, on one use ordinary distilled water, the next with an alkaline solution the the third with acid and note the effects. The latter should start to bubble hence showing a reaction between the two. This has a huge knock on effect with buildings, cliffs, statues, etc as they are worn away by rain which has become acidic.
704222
rain water is mildly acidic (carbonic acid) and so will dissolve minerals found in rock.  For example, if you look at an old building made from limestone the corners will be slightly round and the surface will be pitted.  This is because limestone is made from calcium carbonate which is easily dissolved by acids.\nThis is also the same effect which produces limstone caves and why the surface of rocks appear discoloured and weathered.
509700
All wells have a fresh water spring at the bottom. The water that enters is free to exit, and fresh water from the spring  flows in to replace the water that flowed out. \n\nThe water that is in a well is not exactly stagnant.\nThe water under the  ground is also pure because it is constantly moving through the silt and gets filtered. So the water that comes in is also pure and 'fresh' (though its been around for quite a while!).
242248
Evaporation from the sea. Dig shallow pools and with bis leaves collect the moist. You can also get salt this way. Also collect the water from the rain.
1088292
See the classic landforms and its characteristics in\nhttp://www.geomorph.org/gt/regional/nam.html
503652
False. Caves are found in permeable rock called limestone. Naturally occurring acids dissolve the rock to produce the caves.\n\nThe clue here is containing water. Permeable rock can contain water whereas impermeable rock is resistant to water moving through it.
212250
Observe how climate creates the landscape you observe. Work backwards from the landscape to figure out what chemical and weather processes created those formations.
931995
limestone minerals buffer the acid rain.  The acid reacts with the calcite, etc. in limestone and changes it to more neutral or even slightly basic.  Our groundwater, therefore, tends to have a higher pH even though the pH of rainwater is low.
1065526
Since I answered your other question that was the same question I will add a little more for this question, especially since there is an answer here that has some misinformation. My other answer is at:http://answers.yahoo.com/question/;_ylt=AskJhoayfOFbNHQxqcJCy5gjzKIX?qid=20060616000345AAmblWi\n\nCaves don't all form in limestone, and not all caves form as a result of rainfall dissolving carbon dioxide in the soil and dissolving the rock. Some caves have formed in quartzite (Brazil) some in salt (Israel), and many caves form in gypsum. Caves created by lava flows are refered to as 'psuedokarst' because they do not form by dissolution at all, but simply by lava hardening to form a tube that contains flowing molten lava, and as the lava flow ends the tube empties leaving a cave. \n\nThere are other types of limestone caves as well. Some of the more spectacular limestone caves formed as a result of dissolution by sulphuric acid. The source of the sulphur was somewhat related to petroleum deposits and as these acid waters moved through limestone they dissolved huge caverns. Other types of limestone caves form around islands and deep underground where a chemical contrast between fresh water in the ground, and salt water mixing with this causes limestone to dissolve. These are called mixing zone caves, and in the case of islands are often called flank margin caves. \n\nBesides the spectacular decorative formations in caves (see my other answer) there are hydrologic features in caves that are actually more important than stalactites and stalagmites. Some caves form tunnel-like passages with smooth walls and fairly straight long passages. Some of these are called phreatic tubes. A phreatic tube formed while it was completely filled with water. Other cave passages are known as vadose passages. These types of cave passages formed while partially filled with air, and often flood intermittently. \n\nSome caves form as a deep vertical pit. In some settings these vertical pits are younger than the cave they connect to at the bottom and were formed by corrosive water flowing rapidly down the sides of a fracture or joint in the limestone, gradually enlarging it to become a vertical cave. \n\nHere's link to a major cave (Carlsbad) that formed from sulphuric acid:\nhttp://www.nps.gov/cave/geology.htm\n\nHere are some links to gypsum caves:\nhttp://www.showcaves.com/english/explain/Index/Gypsum.html\n\nHere is a quartzite cave in Venezuela;\nhttp://charlesbrewercarias.orientese.com/cuevas/cuevacharlesbrewer/cuevacharlesbrewering.htm\n\nA salt cave in Israel:\nhttp://www.geology-israel.co.il/WEB%20PAGE/GEO1-2-10=5.HTML\n\nHere is a world's longest and deepest list for caves:\nhttp://www-sop.inria.fr/agos/sis/DB/database.html
652833
A - A meander is a bendy bit of a river.\n\nC - A strange example though. A & B are physical/mechanical weathering and D is through the action of flora/forna. I'm not sure C actually happens often but it is the only chemical action.\n\nB - Limestone will dissolve in a weak acid. Another formation it produces are limestone pavements.\n\nHope this helps