What does gleying indicate in a soil profile?

Gleying in a soil profile is a phenomenon that occurs in waterlogged, anaerobic conditions where the soil remains saturated for extended periods. This saturation leads to a reduction in iron and other ferric compounds, which commonly results in a grayish or bluish coloration of the soil. This color change is an important indicator of the hydrological conditions under which the soil formed and suggests a lack of adequate oxygen, which can greatly affect soil biota and nutrient availability.

The correct answer reflects that gleying signifies markedly reduced conditions due to prolonged saturation, leading to these color changes. This is a critical concept in soil science and is particularly relevant when managing septic systems, as understanding the soil's drainage and water retention characteristics can influence system design and placement.