Parent materials
Amber Anderson
- Match depositional forces and the resulting material/properties
- Predict properties of an area based upon parent materials
- Identify potential management challenges based upon a given parent material
Parent material
A parent material is the substance in which a soil develops. The properties of the original substance will significantly influence the resulting soil profile and properties.
Transporting forces
Several different forces transport materials to the places we find them today. Sometimes, multiple forces combined to deposit the material, such as ice or gravity plus water. Other times, one force deposited a new material on top of an existing, like loess over glacial till, or alluvium over other material. High-energy transporters, like ice, don’t sort the particles as low-energy transporters, like water and wind. Therefore, low-energy transported materials tend to be well-sorted, whereas high-energy transported materials tend to be unsorted.
Ice
During past ice ages, parts of the central US were covered in thick sheets of ice. The massive weight and power of these sheets ground down bedrock in Canada, transporting both small particles and huge boulders. This history of material deposition, along with the following prairie vegetation, have given Iowa the fertile soils present today.
Glacial Till
This material was both carried and deposited by ice. Glaciers covered much of the northern part of the United States, and down into the Northeast corner of Kansas and northern part of Missouri in the central US. Since the ice crossed a variety of bedrock on its trip, these materials usually contain loamy textures (indicating mixed sand, silt, and clay), as well as assorted shapes, colors, and sizes of rocks. Management concerns could be related to the rock fragments found in the material.
Glacial Outwash
This material was carried by ice but sorted by water as it was rushing out of the glacier. Small particles that could stay suspended in water, like silts and clays, were washed away. Larger particles, like sands and gravels, were sorted and deposited at the edge of the current glacier. Management concerns may include low water or nutrient holding capacity. Deposits of outwash can be found across the same region as glacial till, but in pockets or slopes across rather than across a widespread area.
Water
Water is considered a low-energy transporter, leading to sorted materials. These could be coarse or fine. These might have alternating layers if periods of high and low flow normally occur.
Alluvium
Alluvium deposits are formed from running water, as might be found next to a river. Since the size of the material potentially transported is highly dependent on the speed or energy of the water, these are well sorted materials. They can also change in short distances both vertically or horizontally, as rivers may move or carry different amounts of water over time. Alluvial deposits can be found near streams or sometimes up