Geological Work of Ground Water

Date: 2015-10-07; view: 456.

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Exercise 6. Read the text “Geological Work of Ground Water” and find in it the words with the following meanings to fill in the crossword below:

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liquid with something dissolved in it

fixed basin with a water supply and drainage pipe

small river

inner upper surface of a room

outcome or consequence; number obtained from calculation; score; exam mark or grade

process of doing

lower surface of a room

mixing of fine grey powder with water

being deposited by water, ice, or wind

Geological work of ground wateris important in solution and deposition in the rocks through which it passes. It dissolves limestone and other carbonate rocks to form caves and sink holes. Limestone areas are often marked by a karst topography of sinks, few surface streams (they flow underground), and large springs. In caves, the deposition of calcite dissolved in dripping groundwater produces stalactites, icicle-shaped formations hanging from the cave ceilings, and stalagmites, formations that build up from the cave floor. The carrying away of minerals in solution usually occurs above the water table. Below that level, deposition, replacement, and cementation are important. Ball-like masses (concretions), hollow, globular bodies (geodes), and the cement in many sedimentary rocks are the result of the action of ground-water at depth.

Exercise 7. Read the text “Geological work of ground water” andfill in the following diagram: