GEO 101 Lecture 23: Lecture 23 - Caves and Karst Topography
27 Mar 2017
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Document Summary
We discussed groundwater, regions of the groundwater system, recharge, and discharge. Sewage, landfills, toxic waste disposal sites, industry, underground tanks, and agriculture. Serious problem due to indiscriminate practices by industry and citizens. Water can become purified as it passes through an aquifer composed of sand or permeable sandstone (acts as filter) Gravel aquifers do not filter well as the pore openings are too large; groundwater may travel long distances without being cleaned. Contains weak carbonic acid which forms when rainwater dissolves co2 from air. Carbonic acid reacts with calcite in limestone; rock becomes soluble. Caves form in the zone of aeration. Chemical weathering: carbonic acid in groundwater dissolves limestone. Calcite-containing water drips from the cracks in the ceiling of the cave or runs down the walls. Water evaporates a little when it encounters the air in the cave, dropping some of the calcite it was carrying. Calcite builds up over time to form decorative features inside the cave (speleothems)
