weathering Flashcards
3.1-3.4 (34 cards)
what is sediment
sediments comprise loose fragments of rocks or minerals, shells and shell fragments, or mineral crystals that precipitate out of water
how are sediments produced
sediment is produced by weathering
sediment covers bedrock in
variable thicknesses
what is weathering
weathering refers to the combination of processes that break up and corrode solid rock, and may eventually transform it in to loose debris or detritus
in the pipe cleaner analogy
physical weathering is a drain snake
chemical weathering is drano
physical weather is also known as
mechanical weathering
boulder size
> 256mm
cobble size
65-256mm
pebbles size
3-64mm
sand size
1/16-2mm
silt size
1/256-1/16mm
mud size
<1/256mm
what does physical weathering do
breaks intact rocks in to unconnected clasts
what is jointing
rocks buried deep endure enormous pressure and temperature
these rocks can be exhumed
the resulting change in P and T can cause the rock to change shape
natural cracks are known as joints
sedimentary rock jointing
planar vertical joints
igneous plutons jointing
exfoliation
jointing turns intact bedrock in to
separate blocks
what is frost wedging
water get in joints and freezes growing cracks by pushing rocks across
what is salt wedging
dissolved salt precipitates out of water in open spaces in rock
the growing crystals push apart the rock grains
what is root edging
as roots grow they exert a force on the surrounding rock
what is thermal expansion
heat applied to a rock causes the outer layer to expand
how does thermal expansion weather
day night cycles
forest fires
what is chemical weathering
refers to a chemical reaction that alters or destroys minerals
what the 5 commons types of chemical weathering
dissolution
hydrolysis
oxidation
hydration
organic influence