Water is an effective mean of moving earth materials. There are three main types of water transported parent material: (1) alluvial or fluvial parent material transported by rivers or streams, (2) lacustrine or lake deposited parent material, and (3) marine (ocean or sea) deposited parent material.
Transport and deposition in water environment produces rounded and well-sorted materials. Rounding is observed on coarse fragments such as gravels or stones, if present, and results from the smoothing of particles’ rough edges by moving water. Water is also a very effective sorting agent, meaning that parent materials deposited by water tend to have a uniform texture (grain size).
The texture of a water-transported parent material can tell us about the characteristics of the water body in which it was deposited, long after the water has dried out. Turbulent mountain streams only deposit very coarse fragments such as rocks and boulders, while all smaller particles are washed downstream. Fast-flowing, but less turbulent waters allow for gravels to settle and form deposits known as river gravel. Sand settles in calm streams, while silts and clays are transported to still water bodies such as lakes to settle. In very calm environments, such as the middle of lakes or the deep ocean, water-deposited materials consist almost exclusively of clays.
Alluvial or fluvial parent material often has thick layers (strata) of different size particles. Landforms associated with this type of parent material include flood plains, deltas, alluvial fans, and levees.
Marine parent material is collection of sediments that have been carried by rivers and streams to the ocean and eventually sink to the bottom. Such materials can vary in texture.
Lacustrine parent material has been deposited in lakes and is well sorted and fine-textured, composed of fine sand, silt, and clay. Soils formed from lacustrine parent material have low permeability in part because of this fine texture.
Alluvial Environment
Alluvial (or fluvial) parent materials were deposited by moving water bodies such as rivers and streams. The texture of the deposit depends on the energy of the water body. Fast-moving water deposits only coarse material such as rocks and gravel. If the water velocity decreases, finer particles (sand and silt) are deposited, while fine silt and clay particles are deposited by slow-moving water such as that found associated with deltas. Alluvial type of parent material is associated with such landforms as old streambeds, flood plains, deltas, fans, and levees.
Alluvial materials often have very thick layers (strata) of different size material. This occurs over time, as the speed of the water transporting the material changes. Inside strata materials moved by water are well sorted and coarse fragments are rounded.
Delta Formation
Marine Environment
Marine deposits are sediments that accumulate in a marine (ocean or sea) environment. These sediments are later exposed and subjected to soil development because either the ocean floor was uplifted or the water receded. Marine deposits are predominantly of clay size (occasionally may contain some shells), very well sorted, devoid of coarse particles, and usually unstratified (show no layers).
Marine Parent Material
Lacustrine Environment
Still water in lakes permits very fine particles (fine sand, silt, and clay) to settle out and to form lacustrine deposits. These deposits get exposed by elevation of old lakebeds. Lacustrine deposits are very well sorted, devoid of coarse particles such as coarse sand or gravels, and are characterized by thin layers that reflect annual deposition of sediments.