Sediment Transport Flashcards
Dissolved salts that travel until they fall out or PRECIPITATE
Chemical Sediment
Grains of rock and mineral that get carried until they DEPOSIT
Clastic Sediment
What are the different ways that chemical sediments can form?
Direct (chemical) precipitation
Biogenic (organic) precipitation
All the grains are the same exact size
Well sorted Sandstone
Rock version of rounded sediment (internal chunks)
Conglomerate
Rock version of angular sediment
Breccia
What are the four main agents of sediment transport?
- Water (most common)
- Wind (most distinctive)
- Glaciers
- Gravity
Which of these transport mechanisms creates the best sorted and roundest sediment?
Wind Transport
How do Sedimentary Rocks form?
- Old bedrock breaks down
- Sediment travels and changes
- Sediment settles down
- Sediment hardens into rock
New minerals drop out of water
Direct (chemical) precipitation
Examples: Evaporates (halite, gypsum) chert (pure silica)
Organisms extract minerals from water to build bones or shells
Biogenic (organic) precipitation
Examples: Carbonates, chert
Types of Clastic Sediment
Gravel (Rock fragments)
Sand/Silt (mostly quartz)
Mud/Clay (formed during weathering)
Many different grain sizes are mixed up
Poorly-sorted sandstone
Jagged corners break off as grains hit each other. Angular grains become smooth rounded grains
Sediment Rounding
Grains are spherical
Rounded Sediment
Grains are jagged
Angular Sediment
Sediment Cleaning
What happens?
What are the three steps?
As grains travel, unstable minerals break down
Dark rock fragments vanish first
Pink feldspar turn to chalky clay
Finally only pure white quartz is left
Occurs in mass movement.
Moves sediment only a short distance from source
Little rounding, no cleaning or sorting
Gravitational Transport
Sediment is frozen in ice during a transport
Can move sediment a long way without change
LIttle rounding, no cleaning, or sorting
Glacial Transport
Causes physical change (rounding, sorting)
Also causes chemical change (cleaning)
More changes occur
Water Transport
Only fine sediment (sand, silt) can be moved
Physical changes occur but no chemical change
Well-sorted, well rounded, and colorful sand
Wind Transport
