Modelling MountainsYear 4 Science: Beneath Our Feet

Soil Layers

What do you think it looks like beneath our feet?Draw a diagram of the several layers of soil beneath our feet and label each part. Let’s see how close you get to the real thing!

What’s really beneath our feet

O Horizon or Humus

This is the top, organic layer of soil, made up mostly of leaf litter and humus (decomposed organic matter).

A Horizon or Topsoil

The layer called top soil; it is found below the O horizon and above the E horizon. Seeds germinate and plants grow in this dark-coloured layer. It is made up of humus (decomposed organic matter) mixed with the mineral particles

E Horizon or the Eluviation Layer

This eluviation (leaching) layer is light in colour; this layer is beneath the A Horizon and above the B Horizon. It is made up mostly of sand and silt, having lost most of its minerals and clay as water drips through the soil (in the process of eluviation).

B Horizon or Subsoil

Also called the subsoil - this layer is beneath the E Horizon and above the C Horizon. It contains clay and mineral deposits (like iron, aluminum oxides, and calcium carbonate) that it receives from layers above it when mineralized water drips from the soil above.

C Horizon or Regolith

Also called regolith: the layer beneath the B Horizon and above the R Horizon. It consists of slightly broken-up bedrock. Plant roots do not penetrate into this layer; very little organic material is found in this layer.

R Horizon or Bedrock

The unweathered rock (bedrock) layer that is beneath all the other layers.

Cut away hillsides

Have a look at these hillsides…THINK ABOUT:

How would you describe what happened to form these rock and cliff faces?

Did they look the same 100 years ago?

Erosion EROSION is the act in which earth is worn

away, often bywater, wind, or ice. EROSION is also the transfer of particles from one place to another, for example, soils and particles that are produced when a rock is weathered (broken down through natural elements into smaller particles).

A similar process, weathering, breaks down or dissolves rock, weakening it or turning it into tiny fragments.

No rock is hard enough to resist the forces of weathering and erosion.

EXPERIMENT

Annotated Diagram

Roles

COLLECTOR: YOU are responsible for collecting the equipment from the teachers

INSTRUCTOR: YOU are responsible for reading the procedure and instructions to the group members and making sure each step is done accurately.

SPEAKER: YOU will share the responses of your experiment with the rest of Year 4

RECORDER: YOU will be responsible for recording what happens in your experiment.

Discussion

Was your model an accurate model of what it is really like in the environment?

How was it similar/how was it different?Will it give us a good idea of what happens?How do humans affect erosion?