Geo Unit 3 Flashcards
(23 cards)
What is Bedding/Stratification?
When sediment is deposited as distinct layers (beds)
What are the two types of Stratification?
Graded Bedding and Cross-Bedding
What is Graded Bedding?
Coarse grains settle out on the bottom of beds, and finer sediments at the top
Why are the finer grains at the top of graded bedding?
Decrease in energy
What causes Graded Bedding?
Turbidity currents from underwater slope failure
What is Cross-Bedding?
layers at an angle within a given bed
What causes cross-bedding?
wind or water causes sediment to move as distinct bedforms
What are the different forms of cross-bedding?
Ripples from low velocity and dunes from higher velocity
Can you determine the direction of movement and what is “up” in cross-bedding?
Yes
What are the two types of ripples?
Symmetric and Asymmetric
What causes mudcracks?
Fine-grain homogenous material shrinks upon drying
What is the form of mudcracks?
V-Shaped, downward cracks
What is the PHYSICAL Process involved in Lithification?
Compaction
What happens during Compaction?
volume decrease and closer packing of particles
What is Porosity?
the open space between particles
What is Permeability?
the ability of fluids to flow in sediment
What is the CHEMICAL Process involved in Lithification?
Cementation
What happens during Cementation?
The grains are bound together and the porosity is reduced/filled
What are the common types of cement for Cementation?
Silica (Quartz), Calcite, and Iron
Compaction and Cementation affect ___ sedimentary rocks.
ALL
What are the four classifications of sedimentary rocks?
Clastic, Chemical, Biochemical, and Miscellaneous
How are clastic sedimentary rocks classified?
by particle size
What is the mineralogy of clastic sedimentary rocks?
Quartz for sand, clay for finer sizes, and feldspars in immature sediments
