Table of Contents
- 1 When grain size is graded from bottom to top within a single bed it is called?
- 2 What is inverse graded bedding?
- 3 What do we call a bed that has coarse particles at the bottom and becomes finer toward the top?
- 4 What do changes in the tilt of the beds indicate?
- 5 Where does reverse grading occur?
- 6 Where do turbidites form?
- 7 How does size of sediments change as the energy of the medium decreases?
- 8 How do sediment grains sort themselves in graded bedding?
When grain size is graded from bottom to top within a single bed it is called?
Graded bedding is characterized by a gradation in grain size from bottom to top within a single bed.
What is inverse graded bedding?
In reverse or inverse grading the bed coarsens upwards. This type of grading is relatively uncommon but is characteristic of sediments deposited by grain flow and debris flow. It is also observed in Aeolian processes. These deposition processes are examples of granular convection.
What causes inverse graded bedding?
Inverse grading in turbidites is conventionally ascribed to dispersive pressure caused by mutual collisions among grains within a traction carpet or grain flow. If coarser size fractions are available, they will arrive later than the head, permitting the development of inverse grading.
What do we call a bed that has coarse particles at the bottom and becomes finer toward the top?
Graded Bedding. -Bed that has vertical change in particle size; can decrease in grain size (fining upward); can increase in grain size (coarsening upward) -A layer w/ a vertical change in particle size, usually coarse grains at the bottom of the bed to progressively finer grains toward the top (pg. 157)
What do changes in the tilt of the beds indicate?
The original depositional layering is tilted, such tilting not being the result of post-depositional deformation. Cross-bedding forms during deposition on the inclined surfaces of bedforms such as ripples and dunes; it indicates that the depositional environment contained a flowing medium (typically water or wind).
Which of the following lists accurately reflects an increase in grain size from smallest to largest group of answer choices?
An immature clastic rock has well-sorted, resistant grains. D. Pieces of broken rock produced by physical weathering are collectively called clasts or detritus. D.
Where does reverse grading occur?
Reverse-graded beds in this deposit occur where pumice lapilli fell on slopes at or near the angle of repose and formed as parts of the blanket of accumulating pumice became unstable and flowed downslope.
Where do turbidites form?
Turbidites are sea-bottom deposits formed by massive slope failures. Rivers flowing into the ocean deposit sediments on the continenal shelf and slope.
Which of the following lists is written in order of decreasing particle size?
Cards
| Term Which of the following properties does not depend on the chemical composition of an igneous rock/magma? | Definition grain size |
|---|---|
| Term Which of the following lists is written in order of decreasing particle size? | Definition conglomerate, sandstone, siltstone |
How does size of sediments change as the energy of the medium decreases?
As the energy decreases, heavier particles are deposited and lighter fragments continue to be transported. This results in sorting due to density. If the particles have the same density, then the heavier particles will also be larger, so the sorting will take place on the basis of size.
How do sediment grains sort themselves in graded bedding?
Graded Bedding – As current velocity decreases, first the larger or more dense particles are deposited followed by smaller particles. This results in bedding showing a decrease in grain size from the bottom of the bed to the top of the bed. Sediment added as a pulse of turbid water.