Unit 4 Review: Earth Science and APES

Introduction to Unit 4

Unit 4 focuses on Earth Science: plate tectonics, watersheds, soil formation.
Transition from Unit 3 topics: ecology, biodiversity, population.
Key focus areas: plate tectonics, watersheds, soil formation, atmosphere layers, wind patterns, seasons, climate influences, ocean phenomena.

Tectonic Plates: Large lithosphere slabs floating on the mantle.
Mantle: Molten magma sea, heated by Earth's core.
Plate Boundaries:
- Divergent Boundaries: Plates move apart; seafloor spreading, ridges, trenches.
- Convergent Boundaries: Plates collide; oceanic subducts under continental, forms volcanic mountains and trenches.
- Transform Boundaries: Plates slide past; earthquakes common.

Soil Composition:
- Mixture of weathered rock particles (sand, silt, clay) and organic matter.
- Contains pore spaces for air and water.
Soil Formation:
- Weathering of rocks creates mineral components.
- Organic layer (O Horizon), Topsoil (A Horizon), Subsoil (B Horizon), Parent Material (C Horizon).
Weathering vs. Erosion:
- Weathering breaks rocks; erosion moves rock pieces.
- Erosion degrades soil and affects groundwater filtration.
Soil Properties:
- Texture: Proportions of sand, silt, clay.
- Permeability: Ease of water flow.
- Fertility: Influenced by texture, pH, nutrient levels.
- Chemical Properties: pH affects nutrient availability and plant growth.

Atmospheric Composition: 78% nitrogen, 21% oxygen, trace gases.
Layers:
- Troposphere: Weather layer, air we breathe.
- Stratosphere: Contains ozone, UV protection.
- Mesosphere: Middle layer, less dense gases.
- Thermosphere: Hottest layer, auroras.
- Exosphere: Outermost layer, merges with space.
Temperature and Altitude: Opposite relationship at each layer.

Air Properties:
- Warm air holds more moisture; rises and cools.
Hadley Cell:
- Equatorial heat causes warm air to rise and cool, moving moisture to 30° latitudes.
- Trade Winds: Easterly winds from 30° to equator due to Earth’s rotation.

Definition: Land area draining into a water body.
Influences:
- Slope: Separates watersheds; impacts infiltration and runoff.
- Vegetation and Soil Type: Affect water quality and movement.
Urban Impact: Increases runoff and pollution.

Insolation: Solar energy received; affects seasons.
Earth’s Tilt:
- Causes varying insolation and seasons.
- Solstices and Equinoxes: Key positions affecting day length and direct sunlight.

Water Bodies: Winds over water increase moisture leading to precipitation.
Rain Shadow Effect:
- Mountains block rain; windward gets more rain, leeward gets less.
- Example: Sierra Nevada and Mojave Desert.

ENSO: Alternating ocean conditions.
Normal Conditions: Trade winds blow warm water west; upwelling on South America’s coast.
El Niño: Reversed winds, warm water east; affects weather globally.
La Niña: Intensified normal winds; colder, nutrient-rich waters east.

Conclusion: Covered plate tectonics, soil science, atmospheric layers, wind patterns, watersheds, seasons, climate effects, El Niño/La Niña.