Wells and Springs Chemical Weathering

1
Wells and Springs Chemical Weathering

• Section 14.2 and 14.3

2
Types of Wells and Springs

• Ordinary Well- a well that penetrates highly
  permeable rock below the water table

3
Where you would find a spring

• A region where the ground surface drops below the
  water table
• This can occur due to rugged topography or by
  faulting
• Oftentimes where theres a spring, theres a fault

4
Artesian Wells and Springs

• Artesian wells are found far from water sources,
  yet so much water is stores underground, it
  naturally flows to the surface without pumping
• Having a cap rock may assist in forming an
  artesian well because it increases water pressure
  enabling water to naturally flow to the surface
• Artesian springs typically make up the desert
  oasis

5
Hot springs and geysers

• Water that rises to the surface before cooling
  due to contact with a magma chamber
• Geysers are hot springs that erupt periodically

6
Solubility

• The warmer a rock is and the longer water travel
  through rock, more minerals can be dissolved from
  rock.
• Water that contains large amount of dissolved
  minerals is called hard water.
• Hard water usually has a metallic taste.
• One way that minerals become dissolved in
  groundwater is through chemical weathering.

7
Chemical Weathering

• As water moves through soil and other organic
  materials, the water combines with carbon dioxide
  to form carbonic acid.
• This weak acid chemically weathers the rock that
  the acid passes through by breaking down and
  dissolving the minerals in the rock.

8
Results of Weathering by Groundwater

• Caverns- when chemical weathering enlarges a
  number of interconnected cracks
• a natural cavity that forms in rocks as a result
  of the dissolution of minerals also a large cave
  that commonly contains many smaller, connecting
  chambers
• Rocks that are rich in the mineral calcite, such
  as limestone, are especially vulnerable to
  chemical weathering.

9
Caverns
10
Sinkholes

• form when water table drops within caverns. The
  caverns are no longer supported, so a circular
  depression may form due to collapse
• Subsidence sinkholes form by a similar process
  except that as rock dissolves, overlying
  sediments settle into cracks in the rock and a
  depression forms.

11
Results from Chemical Weathering by Groundwater
cont.

• Stalagtites- cone-shaped deposit formed by the
  precipitation of calcium carbonate from overlain
  dissolved limestone
• Stalagmites- the continuation of precipitation of
  calcium carbonate from a stalagtite
• Natural Bridge- an arch formed by the collapse of
  two interconnected sinkholes

12
Sinkhole
13
Natural Bridge
14
Karst Topography

• Basically topography formed by chemical
  weathering of groundwater
• Named after the scenic region of Karst in Croatia