Soil, Agriculture and
Earth Systems Review

Describe the layers of the Earth.
• Include elements
Inner core
Outer core
Mantle
Crust

Oceanic (more dense) and Continental (less dense)
Elements in the Crust: oxygen, silicone, aluminum
Major type of rock found in crust: basalt
Greatest mass: mantle (68%)
Least mass: crust

Magnetic field found in outer core

How do scientists know what events occurred in Earth’s past?
Rocks petrology, etc….fill in later

•

When did reptiles appear on Earth?

Paleozoic
•

Human evolve?

Cenozoic
•

Land plants appeAr?

Paleozoic
•

There five mass extinctions (large numbers of creatures totally disappeared)
•

End Ordovician (ice age)

•

Late Devonian (oxygen disappeared from water) hydrogen sulfide produced by volcanoes

•

End Permian (most severe, 90% of all marine life disappeared due to volcanic eruption)

•

End Triassic (volcanic event)

•

End Cretaceous (meteorites)

•

Human Activity

Lithosphere and Plate Tectonics
• What is the lithosphere? What is the theory of plate tectonics?
Composed of the top part of the mantle and the crust.
7 major plates found here; movement called plate tectonics.
• What is subduction?
Sinking of the oceanic plate under the continental plate. Oceanic crust melts from magma and magma rises up
• Describe the three types of plate boundaries and what they form?
Convergent, divergent, and transform (cc, co, oo)

Volcanoes
• How are volcanoes formed? Where are most volcanoes found?
The Ring of Fire,
• Describe the four types of volcanoes.
Lava domes (layers of lava), composite (strato volcano, ash rocks and lava), cinder (small hill, explosive but w lava only), shield (like a hill but wider, lava flow is slow)
Major gases released; sulfer oxide and carbon dioxide and hydrogen sulfide
Makes sulfuric acid when mixed w local water

Earthquakes
• What causes earthquakes? Where do most occur?
Transform boundary, ring of fire
• How is the magnitude of earthquakes measured?
Richter scale
• Where did the largest earthquake of the 20th century occur?
Chile, 9.5 magnitude

Rocks and Rock Cycle
• Describe how each type of rock is formed?
Igneous (erupting volcano)
Sedimentary (erosion and weathering)
Metamorphic (heat and pressure, transforms igneous and sedimentary)
• What external processes are important to the rock cycle?
Weathering, erosion, compression, uplift (come out from inside volcanoes) Soil Formation
• What the principle components of soil?
6; oxygen, dead organic material, air, silt and clay, water, sand and gravel, fauna and flora
• Summarize the formation of soil.
1 major process; weathering (physical and chemical) breaking down of rocks into smaller pieces, begins formation of soil along w accumulation of organic material
• What factors affect soil formation?
Climate, vegetation, time and human activity
• How do humans affect soil?
Farming; plowing and irrigation
Mining*** (2nd half of ch 14)
Use of fertilizers
Deforestation

Soil Profile
• Describe the horizons of soil
• How do grasslands(prairie), desert (no surface litter, low organic activity) and rainforest (thin and acidic, darker it is the richer in nutrients) soil profiles differ in terms of composition and productivity?
Grasslands thick organic rich in A layer (topsoil)

Soil Degradation
• What is soil degradation? What