Ch 03 - Interior of the Earth11th Fundamentals of Physical Geography
Radius of the Earth
What is the approximate radius of the earth, and why does this make direct observation of its core impossible?
What is the approximate radius of the earth, and why does this make direct observation of its core impossible?
The Earth's Scale
- Radius: The approximate radius of the earth is 6,370 km.
- Observation Limit: Due to this immense depth and the extreme heat and pressure at the core, no human or machine can physically reach the center. Thus, direct observation is restricted to a few superficial kilometers.
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Direct Sources of Information
What are the three primary 'Direct Sources' used to study the physical composition of the earth's interior?
What are the three primary 'Direct Sources' used to study the physical composition of the earth's interior?
Direct Observation Methods
- Mining: Observing surface rocks and extracting materials from deep underground mines (e.g., gold mines in South Africa reaching 3-4 km deep).
- Drilling Projects: Scientific drilling allows sampling of the deeper crust.
- Deep Ocean Drilling Project
- Integrated Ocean Drilling Project
- Example: The deepest drill hole at Kola (Arctic Ocean) reached about 12 km.
- Volcanic Eruptions: Direct chemical analysis of magma/lava that is forcefully expelled to the surface.
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MDV (Mines, Drills, Volcanoes)
Limitations of Deep Drilling
Why is deep scientific drilling technically limited to a few kilometers despite the earth's vast 6,370 km radius?
Why is deep scientific drilling technically limited to a few kilometers despite the earth's vast 6,370 km radius?
The Geothermal Limit
- Deepest Record: The Kola drill hole reached approximately 12 km, which is only a minute fraction of the earth's radius.
- Technical Barrier (Heat): Drilling deeper is currently impossible because temperatures increase rapidly with depth. This extreme heat eventually melts or destroys mechanical drilling equipment.
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Also in this chapter
41 more cards to study in Prism
- 4The Geothermal Gradient
- 5Meteors as an Indirect Source
- 6Gravity Anomaly
- 7Magnetic Field as an Indirect Source
- 8Focus (Hypocentre) vs. Epicentre
- 9Types of Earthquakes
- 10Frequency vs. Magnitude
- 11Richter vs. Mercalli Scale
- 12Immediate Effects of Earthquakes
- 13Tsunamis and Earthquakes
- 14Body Waves vs. Surface Waves
- 15Characteristics of Primary (P) Waves
- 16Characteristics of Secondary (S) Waves
- 17Physical Propagation: P vs. S Waves
- 18Locating the Epicentre (Triangulation)
- 19Concept of the Shadow Zone
- 20Boundaries of P-Wave and S-Wave Shadow Zones
- 21Classifying Earth's Layers
- 22Density Variation in Earth's Interior
- 23Oceanic vs. Continental Crust
- 24The Lithosphere
- 25The Moho Discontinuity
- 26The Asthenosphere
- 27The Chemical Composition of the Core (NIFE)
- 28Physical State: Outer Core vs. Inner Core
- 29The 5 Major Earth Discontinuities
- 30Magma vs. Lava
- 31Classification of Volcanoes by Activity
- 32Shield Volcanoes
- 33Composite Volcanoes (Stratovolcanoes)
- 34Caldera Formation
- 35Flood Basalt Provinces (Deccan Traps)
- 36Mid-Ocean Ridge Volcanoes
- 37Volcanic vs. Plutonic Igneous Rocks
- 38Batholiths
- 39Laccoliths vs. Batholiths
- 40Lapolith (Lopolith)
- 41Phacolith
- 42Sills vs. Sheets
- 43Dykes (Dikes)
- 44Global Distribution of Earthquakes and Volcanoes
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