1. Ocean Sediments
Page 36 in your notebook

2. Ocean Sediments
- Sediments are the solid particles added to the ocean from many different sources.
- Can be classified by their size or by their source
- Physical oceanographers study sediments to learn more about the ocean’s history, chemistry, and nutrient distribution.

3. Sizes of Sediments
- Sediments can be put into categories according to their size.
- Gravel is anything with a diameter of greater than 256 mm to 2 mm in diameter. It is the largest sediment size.
- Sand is anything with a diameter of 2mm to mm. It is ranked from very coarse to very fine.
- Mud is anything less than mm in diameter. It is ranked as either silt or clay.
- A sediment sample is “well-sorted” if it is nearly uniform in particle size.
- A sediment sample is “poorly-sorted” if it is made up of many different particle sizes.

4. Sizes of Sediments
- A sediment sample is “well-sorted” if it is nearly uniform in particle size.
- A sediment sample is “poorly-sorted” if it is made up of many different particle sizes.

5. Sources of Sediment
Sediments are also classified according to where they came from.
This is a really great time to remember your prefixes and suffixes!

6. Terrigenous/Lithogenous Sediments
Terrigenous sediments – any sediment derived from land (rock, wood, windblown ash, etc.)
Lithogenous sediments are those specifically from rocks
Terrigenous sediments are deposited by wind, rain, water, ice, or gravity
Lithogenous sediments on the deep ocean floor are called abyssal clay – it is made of fine rock powder blow to sea and then suspended for many years before sinking.

7. Biogenous Sediments
Biogenous sediments – any sediment derived from living things
Include things such as shells, coral fragments, hard skeletons of plankton, etc.
If a sample of sediments is made up of more than 30% biogenous sediment, it is called an ooze
Calcerous oozes have more calcium carbonate shells
Silaceous oozes have more silica shells

8. Hydrogenous Sediments
Hydrogenous sediments – any sediment created in the water by chemical reactions
Include things such as carbonates, phosphorites, salts, and manganese nodules

9. Cosmogenous Sediments
Cosmogenous sediments – any sediment derived from outer space
Include things such as tektites ( melted particles sprayed outwards and cooled to produce a splash-formed rock)
Also come in a teardrop or rounded shape due to the heat of the Earth’s atmosphere upon entry

10. Ways we Sample Sediments
Dredge – a net or wire basket dragged along the bottom to collect loose bulk materials, surface rocks, or shells
Grab sampler – hinged devices that are spring or weight-loaded to snap shut when the sampler stikes the bottom
Corer – a hollow pipe with a sharp cutting edge that free falls to the bottom and pulls up a cylinder of mud anywhere from meters long
Acoustic profiling – bursts of sound directed at the seafloor reflect or refract according to the type of sediments