Video Summary - Soil Profile and Soil Horizons

Scientific concepts & nature phenomena presented

Soil profile: a vertical sequence of layers showing the different horizons of soil.
Soil horizon: each individual layer within the soil profile, with distinct physical properties.

O horizon (litter)
- Contains dead plant material such as leaves, twigs, sticks, and fallen trees.
- May be thin, thick, or absent depending on the soil type.
A horizon (topsoil)
- Contains rich organic matter plus some minerals.
- Hosts decomposers that break down plant/animal remains.
- Produces humus (dark organic material formed from decayed matter).
E horizon (eluviated layer)
- Named for materials being leached/removed as water moves downward.
- Leads to relative concentration of sand and silt particles.
- Can be missing in some soils.
B horizon (subsoil)
- Typically lighter in color (often reddish/brown) due to less humus.
- Acts as a zone of accumulation where materials (notably clay) collect from water movement downward.
C horizon (parent material)
- Mostly the original material from which soil forms.
- Contains rock fragments.
- Weathering breaks parent rock into smaller pieces.
R horizon (bedrock)
- Massive bedrock that can include granite, basalt, quartzite, limestone, or sandstone.
- Provides the parent material for some soils.