Lesson 2: Soil Formation - WED

Physically breaking down rocks and materials is called__________weathering.

• Chemical
• Mechanical
• Biological
• Permeable

Soil formation begins with the weathering of_______.

• Humas
• Subsoil
• Litter
• Rock

The MAIN  thing Decomposers do for the the soil is the following:

• Store moisture
• Burrow deep in the soil
• Make space for air and water
• Break down and digest dead organisms

Decayed organic material in soil is called______.

• Litter
• Silt
• Humus
• Clay

The two main factors that determine the rate of weathering are the TYPE of rock and_____.

• Music
• Climate
• Size of rock
• Weight of rock

The movement of rocks and weathered materials is called_________.

• Chemistry
• Physical
• Weathering
• Erosion

Topsoil which contains the HUMUS is the soil layer best for growing plants.

• True
• False

In which horizon is most of the HUMUS?

• Horizon A
• Horizon B
• Horizon C
• Horizon D or R

The diagrams shows a rock with water trapped in the cracks during the day and at night. 

Which statement best explains why this process results in weathering?

• frozen water acts as a solute
• water expands when it freezes
• the mass of water increases when it freezes
• frozen water dissolves most types of rock

Why is topsoil darker than all other levels of soil?

• It contains all the darker colored minerals
• It contains volcanic rock
• It contains more organic matter
• It contains bits of burned trees