Study Notes for Earth Science Exam (copy)

Earth's Major Systems

• Biosphere: All living organisms on Earth.

• Atmosphere: The layer of gases surrounding Earth.

• Hydrosphere: Comprises all water on Earth (surface, underground, and atmospheric).

  • Cryosphere: Frozen water, including glaciers and ice.

• Geosphere (Lithosphere): The solid, rocky part of Earth, encompassing rocks and sediments.

Gravitational Force

• Factors Affecting Gravitational Strength:

  • Mass of Objects: Greater mass increases gravitational attraction.

  • Distance: Closer proximity amplifies gravitational force.

Earth's Spherical Shape Formation

• Formation influenced by gravity pulling together dust and debris.

• Early Earth’s interior melted, smoothing imperfections on the surface.

Mass and Size Relationship

• A smaller object can exceed a larger object in mass if it contains more matter.

Density Definition

• Density is expressed as mass divided by volume.

Earth's Dense Layers

• Most Dense Layers Found in Center: During Earth's formation, denser materials sank to the center.

Layers of Earth (Least to Most Dense)

1. Crust

2. Uppermost Mantle

3. Asthenosphere

4. Upper Mantle

5. Lower Mantle

6. Outer Core

7. Inner Core

Understanding Earth's Interior

• Methods Used by Scientists:

  • Deep Well Samples: Analyze material composition, density, and temperature.

  • Seismic Waves: Study wave behavior through layers to understand density changes; identify solid vs. liquid layers.

  • Deep Mine Samples: Similar analysis to well samples for deeper layers.

Lithosphere Composition

• Composed of the crust and uppermost mantle.

Earth's Core Parts

• Outer Core:

  • Liquid due to higher temperature; revealed through seismic wave studies.

• Inner Core:

  • Solid ball of dense iron; extremely high temperature (approx. 6,000°C) and pressure.

Density, Gravity, and Earth's Layers

• Denser materials are pulled towards Earth's center by gravity, forming distinct layers of varying densities.

Asthenosphere Characteristics

• Rocks below the lithosphere are partially melted and can flow (described as plastic).

Temperature and Pressure Trends

• Both increase with depth from the Earth's surface.

Mineral Definition and Properties

• Mineral Requirements:

  1. Naturally occurring

  2. Inorganic

  3. Solid

  4. Definite chemical composition

  5. Orderly atomic arrangement

• External Appearance: Determined by internal atomic structure.

Silicates vs. Non-silicates

• Silicates: Contain silicon and oxygen; e.g., Quartz.

• Non-silicates: Lack silicon and oxygen; e.g., Halite.

Crystallization Process

• Occurs when dissolved particles in water or melt solidify into crystals.

Mineral Formation from Solutions

• From cool solutions: Crystallize as water evaporates.

• From hot solutions: Crystallize when heated solutions cool, often forming veins.

• From Magma: Slow cooling underground yields larger crystals compared to quick cooling lava, which results in small crystals.

Uplift and Stability of Minerals

• Minerals formed at depth may become unstable when uplifted to surface conditions.

Mineralogists

• Scientists who study mineral distribution, properties, and applications.

Physical Properties of Minerals

1. Color: Visual appearance but not definitive for identification.

2. Luster: Reflection quality; categories include metallic and non-metallic.

3. Streak: Powdered color of the mineral.

4. Hardness: Resistance to scratches, measured by Mohs scale (1-10).

5. Cleavage and Fracture:

   • Cleavage: Breaks along smooth surfaces.

   • Fracture: Breaks with uneven surfaces.

6. Density: Mass per unit volume, aids in mineral identification.

7. Special Properties: Unique features like fluorescence or magnetism.

Rock Definition

• A rock is a natural solid mixture of minerals or grains.

Grain Definition and Use

• Grain: Fragments that comprise rocks used for rock classification.

Rock Texture Definition

• Refers to grain size and arrangement in rocks.

Three Major Rock Types

1. Sedimentary Rocks: Formed from compacted sediments.

2. Igneous Rocks: Created from solidified magma or lava.

3. Metamorphic Rocks: Formed from preexisting rocks under heat/pressure.

Formation of Igneous Rocks

• Intrusive: Magma cools slowly underground.

• Extrusive: Magma erupts and cools quickly, forming small crystals.

Sediment Definition

• Material resulting from rocks breaking down through erosion.

Formation of Sedimentary Rocks

• Form via deposition and compaction of layered sediments.

Compaction and Cementation Importance

• Essential for forming sedimentary rocks, filling spaces between sediment grains.

Types of Sedimentary Rocks

• Formed from different processes; sedimentary rocks involve deposited particles.

Metamorphic Rock Formation

• Changes due to heat and pressure lead to texture alteration.

Metamorphism Definition

• The transformation of minerals due to extreme conditions.

Plastic Deformation in Metamorphic Rocks

• Permanent changes in rock appearance due to metamorphism.

Foliated vs. Non-foliated Metamorphic Rocks

• Foliated: Contain aligned minerals; Non-foliated: Random mineral arrangement.

Types of Metamorphism

1. Contact Metamorphism: Occurs near magma contact.

2. Regional Metamorphism: Affects large areas due to high pressure/temperature.

Continental Drift Hypothesis

• Continents are in constant motion validated by fossil evidence across separated landmasses.

Evidence for Continental Drift

• Fossil similarities, geological formations, and climate evidence.

Plate Tectonics Theory

• Earth's surface consists of moving rock plates.

Types of Plate Boundaries

1. Divergent: Plates separate, creating new crust.

2. Transform: Plates slide past each other.

3. Convergent: Plates collide, causing geological features like mountains or subduction zones.

Subduction Zones

• Regions where one plate sinks below another, resulting in various geological formations.

Convection Currents

• Circulating flow in the asthenosphere caused by temperature and density differences.

Catastrophism vs. Uniformitarianism

• Catastrophism: Change occurs rapidly.

• Uniformitarianism: Change occurs slowly and is continuous.

Fossil Formation Conditions

• Favorable conditions include hard body parts and quick burial.

Six Types of Fossil Preservation

1. Preserved Remains

2. Carbon Films

3. Mineral Replacement

4. Molds

5. Casts

6. Trace Fossils

Relative Ages of Rocks

• Principle of Superposition: Oldest layers at the bottom.

• Principle of Original Horizontality: Sediments layer horizontally.

• Principle of Lateral Continuity: Layers extend in all directions.

• Inclusions: Older rocks contained within newer ones.

• Cross-cutting Relationships: Cuts indicate relative age.

Unconformities

1. Disconformity: Weathered rock beneath new sediment.

2. Angular Unconformity: Tilted layers beneath new horizontal layers.

3. Nonconformity: New sediment atop older metamorphic/igneous rock.

Correlation of Rocks

• Matching layers or fossils provides chronological context.

Atoms and Isotopes

• Atoms: Basic units of elements.

• Isotopes: Atoms differing in neutrons.

• Radioactive Decay: Transforming unstable atoms into stable forms.

• Half-life: Time for half of a radioactive sample to decay.

Radiocarbon Dating Process

• Used for timing rock formation by measuring isotope ratios.

Age of Earth

• Determined through dating ancient rock and formations, exceeding 4 billion years.

Earth's Major Systems

Biosphere: All living organisms on Earth, including animals, plants, fungi, and microorganisms, interacting with the abiotic components of the environment such as air, water, and soil.

Atmosphere: The layer of gases surrounding Earth, composed mainly of nitrogen (78%) and oxygen (21%), with trace amounts of other gases. It plays a crucial role in regulating temperature and weather patterns, and protects life from harmful solar radiation.

Hydrosphere: Comprises all water on Earth, including oceans, rivers, lakes, groundwater, and water vapor in the atmosphere. It is vital for life, the climate system, and geological processes.

Cryosphere: Contains frozen water, including glaciers, ice caps, permafrost, and sea ice. It influences global sea levels and climate, and serves as a habitat for many species.

Geosphere (Lithosphere): The solid, rocky part of Earth, encompassing rocks, sediments, and the minerals that make them up. It includes the crust and the uppermost part of the mantle, serving as the foundation for terrestrial ecosystems.

Gravitational Force

Factors Affecting Gravitational Strength:

• Mass of Objects: Greater mass increases gravitational attraction, making larger bodies like planets exert a stronger pull on nearby objects.

• Distance: Closer proximity amplifies gravitational force; as the distance between two objects increases, the gravitational attraction decreases significantly.

Earth's Spherical Shape Formation

The formation influenced by gravity pulling together dust and debris during the early stages of the solar system. As the infant Earth developed, its interior melted, smoothing imperfections on the surface, leading to the roughly spherical shape observed today.

Mass and Size Relationship

A smaller object can exceed a larger object in mass if it contains more matter, highlighting that size does not always equate to mass.

Density Definition

Density is expressed as mass divided by volume, describing how much mass is contained in a given volume of a substance.

Earth's Dense Layers

Most Dense Layers Found in Center: During Earth's formation, denser materials like iron and nickel sank to the center due to gravitational forces.

Layers of Earth (Least to Most Dense)

1. Crust

2. Uppermost Mantle

3. Asthenosphere

4. Upper Mantle

5. Lower Mantle

6. Outer Core

7. Inner Core

Understanding Earth's Interior

Methods Used by Scientists:

• Deep Well Samples: Analyze material composition, density, and temperature to understand geological layers.

• Seismic Waves: Study wave behavior through different layers to understand density changes and identify whether layers are solid or liquid.

• Deep Mine Samples: Similar analysis to well samples allows scientists to explore deeper layers of the Earth’s crust.

Lithosphere Composition

Composed of the crust and uppermost mantle, the lithosphere is crucial for tectonic activity and the formation of landforms.

Earth's Core Parts

• Outer Core: Liquid due to higher temperature; revealed through seismic wave studies, which show the fluid nature of this layer.

• Inner Core: Solid ball of dense iron; experiences extremely high temperatures (approx. 6,000°C) and pressures that keep it in a solid state despite the heat.

Density, Gravity, and Earth's Layers

Denser materials are pulled towards Earth's center by gravity, leading to the formation of distinct layers of varying densities with the heaviest materials at the center and lighter materials on the surface.

Asthenosphere Characteristics

Rocks below the lithosphere are partially melted and exhibit plastic behavior, allowing them to flow slowly over geological timescales, aiding plate tectonics.

Temperature and Pressure Trends

Both temperature and pressure increase with depth from the Earth's surface, significantly affecting physical and chemical processes in the Earth’s layers.

Mineral Definition and Properties

Mineral Requirements:

1. Naturally occurring

2. Inorganic

3. Solid

4. Definite chemical composition

5. Orderly atomic arrangement

External appearance is determined by the internal atomic structure, which influences the mineral's physical properties.

Silicates vs. Non-silicates

• Silicates: Minerals that contain silicon and oxygen; e.g., Quartz, the most abundant group of minerals in the Earth’s crust.

• Non-silicates: Minerals that lack silicon and oxygen; e.g., Halite, commonly known as rock salt.

Crystallization Process

Occurs when dissolved particles in water or melt solidify into crystals, forming distinct mineral structures as conditions allow.

Mineral Formation from Solutions

• From cool solutions: Crystallize as water evaporates, leaving behind mineral deposits.

• From hot solutions: Crystallize when heated solutions cool, often forming veins in rock.

• From Magma: Slow cooling underground yields larger crystals compared to quick cooling lava, which results in smaller, more numerous crystals.

Uplift and Stability of Minerals

Minerals formed at depth may become unstable when uplifted to surface conditions due to changes in temperature and pressure.

Mineralogists

Scientists who study mineral distribution, properties, and applications, providing essential insights into Earth materials.

Physical Properties of Minerals

1. Color: Visual appearance but not definitive for identification; varies due to impurities.

2. Luster: Reflection quality; categorized into metallic and non-metallic types.

3. Streak: The color of the powdered form of the mineral.

4. Hardness: Resistance to scratches, measured by Mohs scale (1-10) to classify minerals.

5. Cleavage and Fracture:

   • Cleavage: Breaks along smooth surfaces, indicating internal atomic arrangement.

   • Fracture: Breaks with uneven surfaces, leading to irregular shapes.

6. Density: Mass per unit volume; aids in mineral identification and differentiating similar-looking minerals.

7. Special Properties: Unique features like fluorescence or magnetism that provide additional identification clues.

Rock Definition

A rock is a natural solid mixture of minerals or grains, key to geological processes and structures on Earth.

Grain Definition and Use

Grain: Fragments that comprise rocks used for rock classification, determining properties and origins.

Rock Texture Definition

Refers to grain size and arrangement in rocks, influencing their appearance and classification.

Three Major Rock Types

1. Sedimentary Rocks: Formed from compacted sediments, often containing fossils or layered features.

2. Igneous Rocks: Created from solidified magma or lava; can be intrusive (cooling slowly underground) or extrusive (cooling quickly on the surface).

3. Metamorphic Rocks: Formed from preexisting rocks under heat/pressure, resulting in texture alteration and new mineral formation.

Formation of Igneous Rocks

• Intrusive: Magma cools slowly underground, resulting in larger crystal formations due to extended cooling times.

• Extrusive: Magma erupts and cools quickly, forming small crystals, often resulting in glassy textures when cooling is extremely rapid.

Sediment Definition

Material resulting from rocks breaking down through erosion, essential for forming sedimentary rocks.

Formation of Sedimentary Rocks

Form via deposition and compaction of layered sediments, often in bodies of water where particles settle out of suspension.

Compaction and Cementation Importance

Compaction reduces the volume of sediments, and cementation fills spaces between sediment grains, solidifying the sediments into rock.

Types of Sedimentary Rocks

Diverse types formed from different processes; classified as clastic, chemical, or biological based on their composition and origin.

Metamorphic Rock Formation

Changes occur due to heat and pressure lead to texture alteration and mineral transformation in rocks.

Metamorphism Definition

The transformation of minerals due to extreme conditions, often resulting in new mineral assemblages and textures.

Plastic Deformation in Metamorphic Rocks

Permanent changes in rock appearance resulting from metamorphism, affecting strength and appearance.

Foliated vs. Non-foliated Metamorphic Rocks

• Foliated: Contains aligned minerals, often forming layers or bands.

• Non-foliated: Exhibits a random arrangement of minerals and lacks layering.

Types of Metamorphism

1. Contact Metamorphism: Occurs near magma contact, creating localized changes.

2. Regional Metamorphism: Affects large areas due to high pressure/temperature conditions over broad regions.

Continental Drift Hypothesis

Continents are in constant motion, supported by fossil evidence across separated landmasses and matching geological features.

Evidence for Continental Drift

Supports for this hypothesis include fossil similarities, geological formations, and climate evidence from different continents.

Plate Tectonics Theory

The theory that Earth's surface consists of moving rock plates, reshaping the planet through geological activity.

Types of Plate Boundaries

1. Divergent: Plates separate, creating new crust as magma rises to the surface.

2. Transform: Plates slide past each other, often causing earthquakes along fault lines.

3. Convergent: Plates collide, leading to geological features like mountains, trenches, or volcanic arcs.

Subduction Zones

Regions where one plate sinks below another, resulting in geological formations such as oceanic trenches and volcanic activity.

Convection Currents

Circulating flow in the asthenosphere caused by temperature and density differences, driving plate tectonics.

Catastrophism vs. Uniformitarianism

• Catastrophism: Rapid changes occur due to catastrophic events such as meteor impacts.

• Uniformitarianism: Change occurs gradually and continuously, explaining geological formations over millions of years.

Fossil Formation Conditions

Favorable conditions for fossilization include hard body parts and quick burial to prevent decay and destruction.

Six Types of Fossil Preservation

1. Preserved Remains: Actual remains of organisms, sometimes in amber.

2. Carbon Films: Thin films of carbon from decomposed organisms on rock surfaces.

3. Mineral Replacement: Original material replaced by minerals over time.

4. Molds: Impressions of organisms left in sediment.

5. Casts: Formed when molds fill with minerals or sediments.

6. Trace Fossils: Evidence of organism activity, like footprints or burrows.

Relative Ages of Rocks

Principles that help determine the chronological order of rock layers include the principle of superposition and lateral continuity.

Inclusions

Older rocks contained within newer ones provide clues to relative age.

Cross-cutting Relationships

Geological features that cut across others must be younger than the features they cut through, providing remnants of geological history.

Unconformities

1. Disconformity: Weathered rock beneath newer sediments creates a gap in geological time.

2. Angular Unconformity: Tilted rock layers beneath new horizontal layers indicate changes in angles over time.

3. Nonconformity: New sediments atop older metamorphic or igneous rock reveal a drastic change in environment and geology.

Correlation of Rocks

Matching layers or fossils across regions can provide chronological context and suggest historical connections between different geological formations.

Atoms and Isotopes

Atoms are the basic units of elements, while isotopes are atoms that differ in the number of neutrons, leading to different atomic weights.

Radioactive Decay

The process by which unstable atoms transform into stable forms over time, allowing for dating methods based on known decay rates.

Half-life

The time required for half of a radioactive sample to decay, a critical factor in radiometric dating.

Radiocarbon Dating Process

A method used for dating ancient organic materials by measuring the ratio of carbon-14 to carbon-12, providing a timeline for past biological activity.

Age of Earth

Determined through dating ancient rock formations, with evidence suggesting the Earth is over 4 billion years old.