8.3 RATES OF EROSION Flashcards
what is unconsolidated sediment?
-material such as sand, gravel, clay and silt that has not been compacted to become sedimentary rock
examples of igneous rocks? (3)
-granite
-basalt
-dolerite
examples of metamorphic rocks? (3)
-slate
-schist
-marble
examples of sedimentary rocks? (3)
-sandstone
-limestone
-shale
what is igneous erosion rate?
VERY SLOW
what is metamorphic erosion rate?
SLOW
what is sedimentary erosion rate?
MODERATE TO FAST
explanation about igneous rocks?
-they are crystalline
-the interlocking crystals make them strong, hard-resistant rock
-granite has few joints to there are limited weaknesses that erosion can exploit
explanation about metamorphic rocks?
-crystalline metamorphic rocks are resistant to erosion
-many have foliation where crystals are orientated in one direction which produces weaknesses
-often folded and heavily fractures
explanation about sedimentary rocks?
-most are clastic and erode faster
-younger rocks tend to be weaker
-rocks with bedding planes (shale) are vulnerable to erosion
do permeable rocks allow water to flow through them?
-yes
do impermeable rocks allow water to flow through them?
-no
what is pore water pressure?
-the pressure water experiences at a particular point below the water table due to the weight of water above it
how can satellite images be useful?
-they show the locations that have rocky shorelines
why are sedimentary rocks more easily eroded than igneous? (3)
-sedimentary consist of loosely packed particles with variable size making them more susceptible to erosion
-sedimentary rocks have bedding planes and jointing which create weakness leading to formation of landforms such as cliffs
-sedimentary rocks have layers of strata, softer layers may erode more quickly than harder