Sedimentary Rocks Flashcards
Weathering
The in-situ breakdown of rock by exposure to the atmosphere
Define mechanical weathering and list some processes
Forced extremes on a rock which leads it to breakdown
Exfoliation, frost shattering, pressure release
Define chemical weathering and list some processes
The breakdown of rocks chemical structure
Carbonation, hydrolysis
Define biological weathering and list some processes
The breakdown of rock due to the action of plants and animals
Burrowing, root action
Grain size
The length of the intermediate axis of the sedimentary grain
Sphericity
How much like a sphere it is
Roundness
Extent to which the originally angular edges and corners have been rounded
Sorting
Expression of overall grain size of the sediment
Name and define the three components of sedimentary rocks
Clasts: dominant larger fragments that usually make up the majority of the rock
Matrix: made up of finer grains that occur between clasts
Cement: too small to be seen by the naked eye, infills spaces and coats grains
What are the agents of erosion
Wind, gravity, rivers/sea, ice
Attrition
Particles collide and get smaller
Abraision
Particles employed by the river to wear away beds/banks
Traction
Larger particles rolling along the bed
Saltation
Sand sized grains bounding along the bed
Suspension
Small particles held in water
Solution
Dissolved ions transporter in the water itself
Compaction
Pushed closer together reducing pourosity
Cementation
Infills pores, coats grains
Facies
Distinctive characteristics of sedimentary rock that link with an environment
Biofacies
Fossil content
Facies association
Group of sedimentary facies that occur together and represent 1 environments
Uniformitarianism
Processes that shape the earth today are the same they were millions of years ago
Till
Sediment deposited by glaciers
Bedding plane
The surface separating 1 bed from another
Wadi
A desert stream channel
Marine transgression
Sea moves inland
Marine regression
Sea retreats
What depth is the CCD
4km
What depth is the abyssal plane
3-6km below the sea
Delta
New land created from deposition of sediments from rivers
Cyclotherm
A repeated sequence of rocks caused by cyclical sedimentation
Flocculation
Where clay particles adhere to one another to form a lagers group with larger settling velocities
Walthers law
In a sedimentary sequence without unconformities a vertical succession of facies represents sedimentary environments that once existed side by side and have migrated over time
