Which type of parent material is Peat or organic?

Peat or organic parent material is primarily formed in wetlands such as marshes or bogs, where there is an accumulation of decomposed plant material in waterlogged conditions. The anaerobic environment prevents the full decomposition of plant matter, leading to the formation of peat, which is rich in organic material. This type of parent material is significant because it influences the soil properties, leading to unique soil profiles with high organic matter content, which impacts water retention, nutrient availability, and biodiversity in the soil ecosystem.

The other options mention different processes or types of materials that do not characterize peat or organic parent materials. For instance, eroded materials refer to physical weathering processes rather than organic accumulation, sticky clay is a specific textural characteristic rather than a type of organic matter, and rocks and gravel signify mineral parent materials instead of organic ones. Understanding the distinction between these types of parent materials is crucial for soil classification and management in ecology and agriculture.