Limited vegetation produces a thin acidic organic layer, also known as humus.
Low temperatures cause a slow rate of decomposition.
Heavy precipitation can cause waterlogging.
Limited vegetation is often found on flat surfaces as relief can cause drainage problems.
Impermeable clays can impede drainage.
Waterlogged soil creates anaerobic conditions, meaning iron compounds are changed from red brown to blue, due to oxygen being extracted by microorganisms.
Cold temperatures conditions mean few organisms can survive.
Re-oxygenation of the iron in the soil can cause a red mottling effect.
Shale, raw lines, and minerals can cause large chunks of angular rock to be brought up to the A and B horizons.