Earth Science Rocks!Warm up October 9Question:Why do you think caring & principled might be

good learner profile terms for your new unit on soil?

Earth Science Rocks!MYP Unit Question: How does

land change?Area of Interaction:

Environment

Learner Profile: Caring and Principled

Earth Science Rocks!Standard: Investigate the

scientific view of how the Earth’s surface is formed.

Learning target: Today I am learning about soil because human survival depends on it.

Activating strategySoil analyzer

Soil…

What is it?

Soil FormationSoil

How does soil form?

Loose weathered material on Earth’s surface where plants can grow

Soil forms as rock is broken down by weathering and mixes with other materials

Bedrock Solid layer of

rock beneath the soil

What is the composition of soil?

Soil is a mixture of rock particles, minerals,

decayed organic material (humus), air, and water

Why is humus good?Makes spaces for air and waterRich in nitrogen and minerals

that plants need to grow

Organisms in the soilLiving things make space for air and

water in soilDecomposers break down the remains

of dead organisms into smaller pieces and digest them with chemicals.

What is a soil’s textureSoil texture depends upon size of individual

particlesGravel – 2mm or largerSand – less than 2 mmSilt - less than 1/16 mmClay – less than 1/256 mm

Clay soilsDense, heavy textureHold a lot of waterNot much space for air

Sandy soilsWater drains quicklyLots of space for airNutrients wash out of the soil

LoamSoil with equal parts clay, sand

and siltCrumbly texture that holds both

air and water

Soil horizonA layer of soil that differs in color

and texture from the layers above or below it.

Mrs. McIntire standing by a soil

profile at

Red Top Mountain.

Soil horizonsA horizon – top soil – crumbly,

dark brown soil that is a mixture of clay, humus, and other minerals

B horizon – sub soil – usually clay and other particles washed down from A horizon, little humus

C horizon – partly weathered rock

How do horizons form?

How do the horizons form?Bedrock weathers and forms C

horizonA horizon develops from C

horizon when plants add organic material to soil and rocks mechanically and chemically weather

B horizon develops when rainwater washes clay and minerals from A horizon into B horizon.