sedimentary Structures
Terms
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- What are sedimentary structures?
- Teatures that form from the sedaments while the sedaments are being deposited.
- How can the current direction be determined from an asymmetrical ripple mark?
- Steep side faces down. Current form in shallow water wave zone.
- How do mud cracks form?
- wet sedaments dry out and shrink and contract..makes tension cracks
- What do swash marks indicate?
- The point of maximum upwash of the waves.
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What is cross stratification?
draw a sketch - Normally occurs in sand stones, forms by migrating sand dunes or sand bars
- List two organic sedimentary structures
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Tracks/Trails
Burrows - Cross-stratification generally occurs in what type of sedimentary rock?
- Sandstone
- What is graded bedding?
-
Decrease in grain size upward due to a deposition by turb...
come back to - What two things might a geologist learn from studying sedimentary structures?
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Environment depositions
acient current directions - The main reasons for stratification in a sedimentary rock are:
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Change in color
Change in grain size
Change in rock type - Can sedimentary structures for in an igneous rock?
- No
- In what environment do symmetrical ripple marks form?
- Shallow wave zones
- Can the wind form ripple marks?
- yes
- What type of sedimentary structure could a worm form?
- Trails
- The dark sands on the beach are called what kind of minerals?
- Heavy