Geology Vocabulary Flashcards
Population Growth
Human History and Growth: Our ancestors have been around for approximately 5 million years, experiencing slight ups and downs in population due to factors like plagues.
Exponential Growth: Humanity currently exhibits exponential growth, meaning the population increases at a rate proportional to its current size. The more people there are, the faster the population tends to grow.
Definition: Exponential growth is a function where the exponent is always changing, implying a direct relationship between population size and its growth rate.
Onset: This rapid growth began notably with the Industrial Revolution, which introduced conditions favorable for population increase, such as improvements in public health, medicine, and overall quality of life.
Life Expectancy: Life expectancy has significantly increased over time. Around 1,000 years ago, it was approximately 30 years.
Growth Rate Trends: Human population grew fastest in the 1970s and 1980s of the 20th century. While the growth rate has slightly declined since then, it is never zero; the global population is always increasing. We add approximately 18 million people to the world per year.
Unprecedented Numbers: It took all of human existence (our species, Homo sapiens, being around for 250,000 to 300,000 years) to reach 1 billion people by 1800. However, we have surpassed 8 billion people in just the last 200 years, demonstrating unprecedented growth in a short period.
Population Density and Distribution
Uneven Distribution: Population density, or people per square area, is not evenly distributed across the Earth.
Factors Influencing Location:
Climate & Temperature: People tend to avoid extremely cold or hot regions. Examples include Greenland, Siberia (Russia), the Sahara Desert (Africa), and Australia's deserts, as well as Antarctica (with only about 12 people in research stations).
Mid-Latitudes: Most people reside in mid-latitudes (between 30 and 60 degrees latitude), which offer more temperate zones, often around western margins of continents, providing suitable conditions for living and agriculture.
Historical and Geographic Concentrations:
Historical Significance: Early civilizations developed around rivers (e.g., Euphrates and Tigris in the Middle East) on flat lands, providing easy access to water for crops, transport, and building.
Flat Lands and Water Proximity: Major population concentrations are generally found in flat areas near water, such as river floodplains (e.g., Bangladesh's delta) and flat coastlines (e.g., Eastern US, West Coast of US).
Volcanic Areas: Paradoxically, volcanic regions also attract high populations due to their incredibly fertile soils, which greatly benefit agriculture (e.g., Mount Popocatépetl in Mexico, Mount Merapi in Indonesia, Mount Fuji in Japan).
Major Population Centers: Concentrations are predominantly in Asia (Southeast Asia, East Asia, Central Asia), including countries like Turkey, Pakistan, India, China, Japan, the Koreas, and Indonesia. Other areas include Central Europe (especially Germany) and Central/Equatorial Africa (especially Nigeria).
Most Populous Nations:
India: Has surpassed China in population.
China: Still one of the most populous.
United States: Followed by Brazil, Indonesia, and Nigeria.
Human Vulnerability and Natural Disasters
Uneven Risk Distribution: While the Earth's land could theoretically be filled, 90\% of the population lives on less than 20\% of the available land. This concentration increases risk in specific areas.
Developing Nations at Higher Risk: Approximately 80\% of people at risk from natural events (that can become disasters) live in developing nations. These nations often have large populations and may lack the infrastructure or resources to mitigate disaster impacts.
Cities Near Plate Boundaries: Approximately 40\% of the world's largest cities are located within 160 kilometers of a plate boundary. This proximity exposes massive populations to geological hazards like earthquakes, tsunamis, and landslides.
The Pacific Ring of Fire:
Description: This region, also known as Circum-Pacific, borders the entire Pacific Ocean and is characterized by intense geological activity.
Concentration of Hazards: It accounts for 75\% of all active volcanoes on Earth's surface and 90\% of all earthquakes. Examples of major cities along this ring include Tokyo (Japan), Mexico City (Mexico), Los Angeles (USA), and Jakarta (Indonesia).
Consequences of High Risk:
Increased Death Tolls: High population density in hazard-prone areas, coupled with buildings not constructed to modern safety codes, significantly increases death tolls during natural disasters.
Economic Losses: Industrialized nations tend to suffer the highest economic losses from disasters due to the value of their infrastructure and economy (e.g., US, Europe, China, Japan, India).
Affected Populations: Bangladesh, India, China, and parts of Southeast Asia, the Middle East, and Eastern Africa are most affected by disasters in terms of the number of people impacted (droughts are significant in Eastern Africa, e.g., Somalia, Malawi, Burundi).
Earthquake Fatalities: Specific periods can highlight particular events. For example, the 2010 Haiti earthquake caused nearly 300,000 fatalities, making Haiti an outlier in a map of earthquake deaths over a specific timeframe.
Tropical Storms: Coastal regions around the world are vulnerable, with the Eastern US (Florida), Central America, Madagascar, Eastern Australia, and East/Southeast Asian coastlines (West Pacific, West Indian Ocean, West Atlantic) being frequently affected.
Introduction to Geology: Earth's Structure
Physiographic Map: A map that displays topography on land (mountains, valleys) and depth in oceans, providing insights into geological features.
Mountains: High mountains are often found on the western margins of continents in the Americas and in a belt across Eurasia (Turkey, Middle East, Pakistan, India, China). Greenland and Antarctica also show 'tall' features, which are thick glaciers.
Ocean Depths: The deepest parts of the ocean floor (trenches) are typically found adjacent to landmasses. Shallow portions often reveal mid-ocean mountain belts.
Views for Geological Study:
Map View (Bird's Eye): A view from above, showing surface features (e.g., roof of a temple).
Cross-Sectional View: A view of the interior, as if cutting through an object, revealing layers and internal structures (e.g., interior of a temple, rock layers at Torrey Pines cliffs).
Examples: Subduction zones (one plate going beneath another) and mid-ocean ridges (where new ocean floor is formed) are often represented in both map and cross-sectional views.
Coastal Erosion: Natural processes like coastal erosion (e.g., Torrey Pines, Southern California) highlight the dynamic nature of Earth's surface and the risks associated with building near unstable coastal edges.
Earth's Layers: Compositional and Mechanical
Earth's Formation and Differentiation (Density Stratification):
Origin: The Earth formed approximately 4.5 billion years ago within a solar nebula (a cloud of gas and dust) that was compressed and formed a disk, possibly initiated by a supernova.
Accretion and Bombardment: Early Earth grew through countless collisions—a process similar to a
Human History and Growth: Our ancestors have been around for approximately 5 million years, experiencing slight ups and downs in population due to factors like plagues.
Population Growth
Exponential Growth: Humanity currently exhibits exponential growth, meaning the population increases at a rate proportional to its current size. The more people there are, the faster the population tends to grow.
Definition: Exponential growth is a function where the exponent is always changing, implying a direct relationship between population size and its growth rate.
Onset: This rapid growth began notably with the Industrial Revolution, which introduced conditions favorable for population increase, such as improvements in public health, medicine, and overall quality of life.
Life Expectancy: Life expectancy has significantly increased over time. Around 1,000 years ago, it was approximately 30 years.
Growth Rate Trends: Human population grew fastest in the 1970s and 1980s of the 20th century. While the growth rate has slightly declined since then, it is never zero; the global population is always increasing. We add approximately 18 million people to the world per year.
Unprecedented Numbers: It took all of human existence (our species, Homo sapiens, being around for 250,000 to 300,000} years) to reach 1 billion people by 1800. However, we have surpassed 8 billion people in just the last 200 years, demonstrating unprecedented growth in a short period.
Population Density and Distribution
Uneven Distribution: Population density, or people per square area, is not evenly distributed across the Earth.
Factors Influencing Location:
Climate & Temperature: People tend to avoid extremely cold or hot regions. Examples include Greenland, Siberia (Russia), the Sahara Desert (Africa), and Australia's deserts, as well as Antarctica (with only about 12 people in research stations).
Mid-Latitudes: Most people reside in mid-latitudes (between 30 and 60 degrees latitude), which offer more temperate zones, often around western margins of continents, providing suitable conditions for living and agriculture.
Historical and Geographic Concentrations:
Historical Significance: Early civilizations developed around rivers (e.g., Euphrates and Tigris in the Middle East) on flat lands, providing easy access to water for crops, transport, and building.
Flat Lands and Water Proximity: Major population concentrations are generally found in flat areas near water, such as river floodplains (e.g., Bangladesh's delta) and flat coastlines (e.g., Eastern US, West Coast of US).
Volcanic Areas: Paradoxically, volcanic regions also attract high populations due to their incredibly fertile soils, which greatly benefit agriculture (e.g., Mount Popocatépetl in Mexico, Mount Merapi in Indonesia, Mount Fuji in Japan).
Major Population Centers: Concentrations are predominantly in Asia (Southeast Asia, East Asia, Central Asia), including countries like Turkey, Pakistan, India, China, Japan, the Koreas, and Indonesia. Other areas include Central Europe (especially Germany) and Central/Equatorial Africa (especially Nigeria).
Most Populous Nations:
India: Has surpassed China in population.
China: Still one of the most populous.
United States: Followed by Brazil, Indonesia, and Nigeria.
Human Vulnerability and Natural Disasters
Uneven Risk Distribution: While the Earth's land could theoretically be filled, 90\% of the population lives on less than 20\% of the available land. This concentration increases risk in specific areas.
Developing Nations at Higher Risk: Approximately 80\% of people at risk from natural events (that can become disasters) live in developing nations. These nations often have large populations and may lack the infrastructure or resources to mitigate disaster impacts.
Cities Near Plate Boundaries: Approximately 40\% of the world's largest cities are located within 160 kilometers of a plate boundary. This proximity exposes massive populations to geological hazards like earthquakes, tsunamis, and landslides.
The Pacific Ring of Fire:
Description: This region, also known as Circum-Pacific, borders the entire Pacific Ocean and is characterized by intense geological activity.
Concentration of Hazards: It accounts for 75\% of all active volcanoes on Earth's surface and 90\% of all earthquakes. Examples of major cities along this ring include Tokyo (Japan), Mexico City (Mexico), Los Angeles (USA), and Jakarta (Indonesia).
Consequences of High Risk:
Increased Death Tolls: High population density in hazard-prone areas, coupled with buildings not constructed to modern safety codes, significantly increases death tolls during natural disasters.
Economic Losses: Industrialized nations tend to suffer the highest economic losses from disasters due to the value of their infrastructure and economy (e.g., US, Europe, China, Japan, India).
Affected Populations: Bangladesh, India, China, and parts of Southeast Asia, the Middle East, and Eastern Africa are most affected by disasters in terms of the number of people impacted (droughts are significant in Eastern Africa, e.g., Somalia, Malawi, Burundi).
Earthquake Fatalities: Specific periods can highlight particular events. For example, the 2010 Haiti earthquake caused nearly 300,000 fatalities, making Haiti an outlier in a map of earthquake deaths over a specific timeframe.
Tropical Storms: Coastal regions around the world are vulnerable, with the Eastern US (Florida), Central America, Madagascar, Eastern Australia, and East/Southeast Asian coastlines (West Pacific, West Indian Ocean, West Atlantic) being frequently affected.
Introduction to Geology: Earth's Structure
Physiographic Map: A map that displays topography on land (mountains, valleys) and depth in oceans, providing insights into geological features.
Mountains: High mountains are often found on the western margins of continents in the Americas and in a belt across Eurasia (Turkey, Middle East, Pakistan, India, China). Greenland and Antarctica also show 'tall' features, which are thick glaciers.
Ocean Depths: The deepest parts of the ocean floor (trenches) are typically found adjacent to landmasses. Shallow portions often reveal mid-ocean mountain belts.
Views for Geological Study:
Map View (Bird's Eye): A view from above, showing surface features (e.g., roof of a temple).
Cross-Sectional View: A view of the interior, as if cutting through an object, revealing layers and internal structures (e.g., interior of a temple, rock layers at Torrey Pines cliffs).
Examples: Subduction zones (one plate going beneath another) and mid-ocean ridges (where new ocean floor is formed) are often represented in both map and cross-sectional views.
Coastal Erosion: Natural processes like coastal erosion (e.g., Torrey Pines, Southern California) highlight the dynamic nature of Earth's surface and the risks associated with building near unstable coastal edges.
Earth's Layers: Compositional and Mechanical
Earth's Formation and Differentiation (Density Stratification):
Origin: The Earth formed approximately 4.5 billion years ago within a solar nebula (a cloud of gas and dust) that was compressed and formed a disk, possibly initiated by a supernova.
Accretion and Bombardment: Early Earth grew through countless collisions—a process similar to a snowball rolling downhill, accumulating material and increasing in size.
Classification of Earth's Layers: Earth's interior can be classified based on two main properties: compositional (chemical makeup) and mechanical (physical state/strength).
Compositional Layers:
Crust: The outermost solid layer.
Continental Crust: Thicker (25 to 70 km), less dense, primarily composed of silicon, oxygen, aluminum (felsic rocks like granite).
Oceanic Crust: Thinner (5 to 10 km), denser, primarily composed of silicon, oxygen, magnesium, iron (mafic rocks like basalt).
Mantle: Located beneath the crust, extending to about 2,900 km depth.
Composed primarily of silicate minerals rich in iron and magnesium (ultramafic rocks like peridotite).
Makes up about 84\% of Earth's volume.
Core: The innermost layer, composed mostly of iron and nickel.
Outer Core: Liquid layer, responsible for Earth's magnetic field.
Inner Core: Solid sphere at the center, due to immense pressure, despite high temperatures.
Mechanical Layers:
Lithosphere: The uppermost mechanical layer.
Definition: The strong, rigid outer shell of the Earth.
Composition: Includes the entire crust and the uppermost part of the mantle.
Thickness: Averages about 100 km, but can vary from a few kilometers beneath mid-ocean ridges to 200 km or more beneath continents.
Plate Tectonics: Broken into large, moving pieces called tectonic plates.
Asthenosphere: Directly beneath the lithosphere.
Definition: A weaker, deformable layer within the upper mantle.
Properties: Solid, but ductile (plastic-like), allowing it to flow slowly over geological time.
Enables the movement of the lithospheric plates above it.
Mesosphere (Lower Mantle): Extends from the asthenosphere to the outer core.
Properties: Solid, but more rigid than the asthenosphere, due to increasing pressure.
Outer Core: The liquid layer of iron and nickel, same as the compositional outer core.
Magnetic Field: Its convection generates Earth's magnetic field.
Inner Core: The solid, innermost sphere of iron and nickel, same as the compositional inner core.
High Pressure: Remains solid despite extremely high temperatures due to immense pressure.