Earth Science: Magma and Heat Processes

Metamorphism

• Heat is a major driving force behind metamorphism. Rocks may be exposed to intense heat from nearby magma bodies or due to burial deep within the Earth’s crust.
• Pressure also plays a key role. As rocks are buried deeper, the weight of overlying rocks creates enormous pressure, which can cause the minerals in the rock to recrystallize.
• Chemically active fluids can also contribute to metamorphism. These fluids can react with the minerals in the rock, altering their composition and structure.

Mineral Melting

• Partial melting is the process where different minerals in a rock melt at different temperatures and pressures, leaving behind a residue of unmelted minerals.

Magma & Lava

• Magma is molten rock found beneath the Earth’s surface.
• Lava is molten rock that has erupted onto the Earth’s surface.

Basaltic Magma

• Basaltic magma is characterized by its low silica content, which makes it relatively fluid and less likely to erupt explosively.

Seafloor Spreading Theory

• **The theory that the ocean floor is slowly spreading apart at mid-ocean ridges and creating new crust is supported by evidence such as the magnetic striping pattern on the seafloor, the age of oceanic crust, the presence of transform faults, and the discovery of deep-sea trenches.

Plate Boundaries

• Transform plate boundaries involve the plates sliding past each other horizontally, often causing earthquakes.

Rock Stress

• Tension, compression, and shear are the three main types of stress that can affect rocks and cause faults.

Fault Types

• Normal faults occur when the hanging wall slips downward relative to the footwall.

Law of Superposition

• The Law of Superposition states that in undisturbed rock layers, the oldest layers are found at the bottom and the youngest layers are found at the top.

Radiometric Dating

• Radiometric dating is a method of determining the age of rocks by measuring the relative amounts of parent and daughter isotopes.

Geologic Time

• Relative time describes the order in which events occurred, while absolute time provides a numerical age for geologic events.

Geologic Hazards

• Natural disasters such as earthquakes, volcanic eruptions, tsunamis, floods, landslides, and meteorite impacts are all considered geologic hazards.

Coastal Erosion

• Types of coastal erosion include wave erosion, wind erosion, tidal erosion, and biological erosion, but glacial erosion is not a type of coastal erosion.

Coastal Protection

• Coastal protection efforts, though often effective, can't always prevent all erosion and submersion along coastlines.