chemical weathering

karst landscape

• shaped by chemical weathering and and erosion of soluble rocks e.g limestone, dolomite and gypsum

limestone composition

• mainly composed of calcium carbonate - highly affected by chemical weathering

examples in ireland

• The Burren Co. Clare

• well known karst region formed around 350 MYA during carboniferous period

carbonation process

• main form of chemical weathering in limestone areas

• involves rainwater absorbing carbon dioxide to form weak carbonic acid

chemical reaction

• acid reacts with calcium carbonate in limestone to form Calcium bicarbonate

• soluble and carried by water

widening of joints

• over time, carbonation enlarges joints and bedding planes

• gradually shaping rocks

limestone pavement

• key surface feature consists of exposed, flat limestone bed rock with widened joints

clint’s and grikes

• Clint’s: solid, flat blocks of rock

• Grikes: deep fissures that separate them

Karrens

• small, shallow hollows on clint’s where water collects and continues to dissolve the rock

Fluting

• occurs when acidic water runs down the edges of clint’s, carving grooves into the rock surface

swallow holes

• form where rivers sink underground upon meeting limestone

dry valleys and rivers of resurgence

• downstream from swallow holes, rivers often leave dry valleys and reappear as rivers of resurgence

sinkholes

• circular depressions formed when underground voids collapse due to ongoing carbonation

Turloughs

• seasonal lakes (turloughs) form when underground passageways fill with water during wet periods forcing water to rise to surface

impact of carbonation

• responsible for creating both surface and underground karst features, altering the landscape over time.