Earth Systems and Resources Notes
Learning Outcomes for Earth Systems and Resources
By the end of this unit, students will be able to understand the following core concepts:
Earth Spheres ( major divisions).
Layers of the Earth (Chemical and physical properties).
Plate Tectonics (Theory, history, and movement).
Soil Formation and Soil Degradation.
Layers of the Atmosphere.
Urban Planning and Urban Sprawling.
Earth’s Spheres
The Earth is divided into four major spheres which constitute its global systems:
Atmosphere: This consists of the multiple layers of air surrounding the Earth.
Hydrosphere: This includes all of Earth’s liquid water, water vapor, and the cryosphere (all areas where water is frozen).
Geosphere: This includes Earth’s molten and solid rocks, minerals, and soil. The primary focus within this unit is the lithosphere, which comprises the Earth’s crust and the upper mantle.
Biosphere: This includes all living things on Earth and the interactions between them.
Interconnectivity: Each of these systems interacts with the others, resulting in a state of balance. The unit focuses specifically on how the geosphere, atmosphere, and hydrosphere are affected by the sun's energy.
Internal Structure and Layers of the Earth
There are four main layers that make up the Earth:
Crust: The outermost layer, classified into two distinct types:
Continental Crust: Characteristics include being thicker, less dense, and composed of many different kinds of rocks.
Oceanic Crust: Characteristics include being thinner, more dense, and primarily composed of basalt and gabbro.
Mantle: Divided into the upper mantle and the lower mantle.
Upper Mantle: This is further divided into two regions:
Lithosphere: This is a very solid layer consisting of the outermost part of the upper mantle plus the crust. It is a primary focus for the study of plate tectonics.
Asthenosphere: Located below the lithosphere but above the lower mantle. It is made of solid rock that is denser, weaker, malleable, and semi-flowing.
Lower Mantle (Mesosphere): This is a solid, brittle layer situated between the upper mantle and the outer core. It comprises approximately of the Earth’s total volume.
Outer Core: A liquid layer composed mainly of Iron () and Nickel (), with small amounts of silicon and oxygen. The Earth’s magnetic field is generated here because convective energy in the outer core is converted into electrical and magnetic energy.
Inner Core: The innermost layer of the Earth, consisting of a solid ball of Iron (). It also plays a role in helping to create the magnetic field.
The Theory of Plate Tectonics
Definition: This theory explains that the lithosphere (the uppermost layer of Earth) is divided into large, moving masses known as plates.
Historical Context: Alfred Wegener is recognized as the "Father of Plate Tectonics."
In , he proposed the concept of "Continental Drift."
Continental Drift: The hypothesis that all landmasses were once joined as a single continent and have since been slowly moving away from each other.
Reception: Wegener was initially ridiculed by many scientists. His ideas were not widely accepted until approximately years later.
Evidence for Continental Drift: Wegener highlighted four primary pieces of evidence:
Jigsaw: The visible fit between the coastlines of various continents.
Geological patterns: Matching rock structures and mountain ranges across oceans.
Fossil Evidences: Similar plant and animal fossils found on widely separated continents.
Continental movement: Observations of the shifting positions of land masses.
Mechanism of Movement: Tectonic plates move due to convection currents occurring in the mantle. This involves a circular movement of energy from the core to the mantle, causing hotter rock to rise and cooler rock to fall.
Plate Boundaries and Geological Features
Boundaries: These are the locations where tectonic plates touch. There are three primary types:
Convergent Boundary: Plates move toward each other. Features include:
Mountains.
Volcanoes.
Subduction Zones: Occur when one plate hits another and the denser plate (typically oceanic) slides below the less dense plate (typically continental).
Trenches.
Island Arcs.
Violent, deep earthquakes.
Divergent Boundary: Plates move away from each other. Features include:
Ridges: Created as new crust forms from rising magma that cools on the surface.
Seafloor spreading.
Rift valleys.
Volcanoes.
Nonviolent earthquakes.
Transform Boundary: Plates slide past each other. Features include:
Faults: Formed when large portions of rock break off.
Shallow earthquakes.
Hot Spots and Earthquakes
Hot Spot: An intensely hot area within the mantle. Large plumes of hot mantle material rise from deep within the Earth. As a tectonic plate moves over a stationary hotspot, it can form a linear chain of volcanoes. Hotspots are identified as volcanoes appearing in random locations, often far from the edge of a tectonic plate.
Earthquake: A sudden and violent shaking of the Earth’s surface. It is caused by the movement of tectonic plates along a fault line. When stress overcomes a "locked fault," stored energy is released. Earthquakes typically occur around plate boundaries.
Questions & Discussion
Exercise A: Labeling Earth Layers: Identify the layers in a diagram using the following word bank:
Lithosphere
Mantle
Core
Oceanic Crust
Outer Core
Asthenosphere
Continental Crust
Inner Core
Exercise B: Map Identification: Based on a map where lines represent boundaries and red arrows represent movement direction, identify the locations for specific features:
Where would Volcanoes most likely be located?
Where would an Island Arc be located?
Where is a Hot Spot indicated?
Where do Earthquakes occur?
Where are Faults located?
Reference Labels: A, B, C, D