Discuss the change that would occur in sediments during transportation by a stream from the source to it's basin of deposition?

During transportation by a stream from the source to its basin of deposition, sediments undergo several changes. These changes can be categorized into physical, chemical, and biological processes.

1. Physical changes: As sediments are transported by a stream, they undergo physical weathering processes such as abrasion, attrition, and sorting. Abrasion occurs when sediments rub against each other or against the streambed, leading to the rounding of edges and the breakdown of larger particles into smaller ones. Attrition refers to the wearing down of sediments into smaller fragments through repeated collisions. Sorting occurs as sediments of different sizes and densities are separated and deposited in different locations along the stream's path.

2. Chemical changes: During transportation, sediments may undergo chemical weathering processes such as dissolution, oxidation, and hydration. Dissolution occurs when minerals in the sediments are dissolved in the water, leading to the release of ions into the stream. Oxidation occurs when minerals react with oxygen in the water or air, leading to the formation of new minerals. Hydration refers to the absorption of water molecules by minerals, causing them to expand and potentially break apart.

3. Biological changes: Sediments transported by a stream may also undergo biological processes such as bioturbation and bioerosion. Bioturbation refers to the mixing of sediments by burrowing organisms such as worms and insects, which can disrupt sediment layers and mix different types of sediments together. Bioerosion occurs when organisms such as mollusks and crustaceans bore into sediments, leading to the breakdown of sediment particles.

Overall, the transportation of sediments by a stream leads to the physical, chemical, and biological alteration of the sediments, resulting in changes in their size, shape, composition, and distribution along the stream's path. These changes ultimately influence the characteristics of the sediments deposited in the basin of deposition, shaping the landscape and ecosystem of the area.

Changes in Sediments during Stream Transportation

As sediments travel along a stream from its source to its basin of deposition, they undergo significant changes due to erosion, transportation, and deposition processes. The following changes typically occur:

1. Reduction in Grain Size:

- As sediments are transported downstream, they collide with each other and the streambed, which gradually breaks them into smaller fragments.
- This process, known as attrition, reduces the average grain size of the sediments.

2. Sorting by Size and Shape:

- The velocity of a stream varies with depth and distance from the banks.
- Larger, denser particles require higher velocities to be transported, so they tend to be deposited closer to the source while smaller, less dense particles are carried farther downstream.
- This sorting process results in layers of sediments with different grain sizes and shapes.

3. Rounding of Grains:

- As sediments are transported, they roll along the streambed, which gradually smooths their edges and corners.
- This process, known as abrasion, produces rounded or subrounded grains.

4. Mixing of Sediments:

- Stream currents can cause different types of sediments to mix and form heterogeneous mixtures.
- This mixing process can result in sediments with a wide range of compositions and textures.

5. Chemical Alteration:

- Streams can contain dissolved ions that can react with the minerals in sediments.
- This chemical alteration can change the composition of the sediments and produce new minerals.

6. Biological Activity:

- Organisms such as bacteria, fungi, and plants can grow on and within sediments.
- Their activities can alter the chemical and physical properties of the sediments.

Changes from Source to Deposition Basin

As sediments are transported from their source to the basin of deposition, the changes described above become more pronounced. The following general trends can be observed:

- Sediments at the source tend to be coarse-grained and angular, with little sorting.
- Sediments in the middle reaches of the stream are often medium-grained and subrounded, with some sorting.
- Sediments in the lower reaches of the stream are typically fine-grained and well-sorted.
- Sediments in the basin of deposition are often highly sorted and compacted, with a wide range of grain sizes and compositions.