1. Marine Sedimentation

2. Sediment in the Sea -Sediment is classified in two ways: Size and Origin -Size is based on the Wentworth grain-size scale -Size classification divides sediment by grain size into gravel, sand, and clay. Mud is a mixture of silt and clay. SedimentTypeDiameter in mm GravelBoulderLarger than 256.0 Cobble65.0-256.0 Pebble4.0-64.0 Granule2.0-4.0 SandVery Coarse1.0-2.0 Coarse0.50-1.0 Medium0.25-0.50 Fine0.125-0.25 Very Fine0.0625-0.125 MudSilt0.0039-0.0625 Clay0.0002-0.0039 Colloid Smaller than 0.0002 Wentworth Grain-Size Scale

3. Sediment in the Sea Origin classification divides sediment into five categories:

4. Sediment in the Sea Origin classification divides sediment into five categories: – Terrigenous sediments – fine to coarse grains that are produced by the weathering and erosion of rocks on land, typically sand and mud.

5. Sediment in the Sea Origin classification divides sediment into five categories: – Biogenous sediments – fine to coarse grains that are derived from the hard parts of organisms, such as shells and skeletal debris, typically lime (calcium carbonate) and siliceous mud (silicates)

6. Sediment in the Sea Origin classification divides sediment into five categories: – Hydrogenous/Authigenic sediments – particles that are precipitated by chemical or biochemical reactions in seawater near the sea-floor; manganese and phosphate nodules are examples.

7. Sediment in the Sea Origin classification divides sediment into five categories: – Volcanogenic sediments – particles that are ejected from volcanoes, like ash

8. Sediment in the Sea Origin classification divides sediment into five categories: – Cosmogenic sediments – very tiny grains that originate from outer space and tend to be mixed into terrigenous and biogenic sediment. – Hard to distinguish from other sediments due to size!

9. B. Factors that control sedimentation Includes particle size and the turbulence of the deposition environment. – So a larger, heavier sediment particle will not travel as far down a river as a lighter, smaller sediment particle. – Heavier, larger particles require faster and stronger water currents to move them. Nile River Mouth   Stream bed with various sized sediments

10. B. Factors that control sedimentation Hjulstrom’s Diagram graphs the relationship between particle size and energy for erosion, transportation, and deposition (when the sediment is too heavy to move).

11. C. Sedimentation in the Ocean Terrigenous sediments are found on the continental shelf. Seaward, water becomes deeper and more distant from a terrigenous source.

12. C. Sedimentation in the Ocean - Worldwide distribution of recent shelf sediments by composition is strongly related to latitude and climate.

13. C. Sedimentation in the Ocean - Worldwide distribution of recent shelf sediments by composition is strongly related to latitude and climate. – 1. Calcareous biogenous sediments dominate tropical shelves.

14. C. Sedimentation in the Ocean - Worldwide distribution of recent shelf sediments by composition is strongly related to latitude and climate. – 2. River-supplied sands and muds dominate temperate shelves.

15. C. Sedimentation in the Ocean - Worldwide distribution of recent shelf sediments by composition is strongly related to latitude and climate. – 3. Glacial till and ice-rafted sediments dominate polar shelves.

16. C. Sedimentation in the Ocean If influx of terrigenous sediment is low and the water is warm, carbonate sediments will dominate.

17. C. Sedimentation in the Ocean - Deep-sea Sedimentation has 4 main sources for sediment: terrigenous material from the land (found mostly on the shelf), biogenous and hydrogenous from the sea, and volcanic from mid-ocean ridges and other active sites.

18. C. Sedimentation in the Ocean Deep-sea Sedimentation has 4 main sources for sediment: terrigenous material from the land (found mostly on the shelf), biogenous and hydrogenous from the sea, and volcanic from mid-ocean ridges and other active sites. Major pelagic (open ocean) sediments in the ocean are red clay and biogenous oozes. Red Clay Sands on the ocean floor are composed of the shells of living things.

19. C. Sedimentation in the Ocean Deep-sea Sedimentation has 4 main sources for sediment: terrigenous material from the land (found mostly on the shelf), biogenous and hydrogenous from the sea, and volcanic from mid-ocean ridges and other active sites. – Hydrogenous deposits are chemical and biochemical precipitates that form on the sea floor and include ferromanganese nodules and phosphorite.

20. C. Sedimentation in the Ocean - Deep-sea Sedimentation has 4 main sources for sediment: terrigenous material from the land (found mostly on the shelf), biogenous and hydrogenous from the sea, and volcanic from mid-ocean ridges and other active sites. – Volcanic sediments come directly from volcanoes and are found primarily near mid-ocean ridges and island hotspots.

21. C. Sedimentation in the Ocean The distribution of sediments in the deep ocean varies greatly, but some parts of the ocean are dominated by certain types.

22. C. Sedimentation in the Ocean The distribution of sediments in the deep ocean varies greatly, but some parts of the ocean are dominated by certain types. New crust at the mid-ocean ridge has little sediment covering it, where the sea floor close to the continents have great amounts of sediment, and in differing layers.

23. C. Sedimentation in the Ocean The distribution of sediments in the deep ocean varies greatly, but some parts of the ocean are dominated by certain types. These sedimentary layers create the great flat expanses of the Abyssal Plains.

24. C. Sedimentation in the Ocean The distribution of sediments in the deep ocean varies greatly, but some parts of the ocean are dominated by certain types. New crust at the mid-ocean ridge has little sediment covering it, where the sea floor close to the continents have great amounts of sediment, and in differing layers. These sedimentary layers create the great flat expanses of the Abyssal Plains. Copy into notes