Six soil layers from top to bottom?

Answer 1

OrdersOrders are the highest category of soil classification. Order types end in the letters sol. In the US classification system, there are 10 orders:[24]

• Entisol - recently formed soils that lack well-developed horizons. Commonly found on unconsolidated sediments like sand, some have an A horizon on top of bedrock.
• Vertisol - inverted soils. They tend to swell when wet and shrink upon drying, often forming deep cracks that surface layers can fall into.
• Inceptisol - young soils. They have subsurface horizon formation but show little eluviation and illuviation.
• Aridisol - dry soils forming under desert conditions. They include nearly 20% of soils on Earth. Soil formation is slow, and accumulated organic matter is scarce. They may have subsurface zones (calcic horizons) where calcium carbonates have accumulated from percolating water. Many aridiso soils have well-developed Bt horizons showing clay movement from past periods of greater moisture.
• Mollisol - soft soils with very thick A horizons.
• Spodosol - soils produced by podsolization. They are typical soils of coniferous and deciduous forests in cooler climates.
• Alfisol - soils with aluminum and iron. They have horizons of clay accumulation, and form where there is enough moisture and warmth for at least three months of plant growth.
• Ultisol - soils that are heavily leached.
• Oxisol - soil with heavy oxide content.
• Histosol - organic soils.

Other order schemes may include:

• Andisols - volcanic soils, which tend to be high in glass content.
• Gelisols - permafrost soils.