(1) Introduction Flashcards
What is Geology
The scientific study of the earth
4 spheres that make up Earth
Geosphere (solid earth), Atmosphere (gaseous), Hydrosphere (water in all 3 forms), Biosphere (life-forms).
The interaction between the spheres is continuing since Earth formed.
Physical Geology
- Major branch of Geology which deals with:
- Materials that make up the Earth
- Changes in the surface and interior of Earth
- Forces that cause those changes
“The Dynamic Earth”
- The earth is constantly changing.
- Geologic changes occur in an instant (volcano, earthquake), or over millions/billions of years.
Species come and species go. The only constant for life on earth is change.
Why study Geology
- Direct applications to soils, engineering, chem, physics, and bio.
- Potential career as geologists.
- Natural phenomena are interesting.
- Knowledge about natural geologic hazards.
- Protecting our environment.
- Context of ourselves as humans in relation to planet earth.
Geological materials supply things human society needs.
Geologic Resources: Energy Resources & Mineral Resources
Materials of geologic origin that we extract from the earth for our use. ER: petroleum, coal, uranium, geothermal energy, plastics (derived from petroleum). MR: metals (aluminum) and non-metals (salt)
Base Metals vs Precious Metals
BM: iron, copper, aluminum, lead, nickel, zinc
PM: gold, silver, platinum
Earth’s Interior
Three major concentric zones: Crust, Mantle, and Core
Crust
- Outer layer of rock that forms a thin skin on the earth.
- Relatively rigid.
- 2 types: Oceanic: avg 7 km thick, dense; Continental: 10-70 km thick, avg 30-50 km, thickest under mountains, less dense.
Why oceanic crust denser than continental crust?
- Oceanic crust is made of rock that have denser material
- Oceanic crusts higher in Mg and Fe lower in Si, Na, and K
- Nothing to do with water in top
Mantle
- Middle zone of the earth.
- 2900km thick.
- Inaccessible to direct observation (studied mainly through geophysical methods).
- Solid rock (but high in T and P = plastic behavior)
- BUT parts flow slowly
Core
- Innermost zone of earth
- 3470km thick
- Consists of inner (solid) and outer (liquid) zones
- Inaccessible to direct observation
- Probably consists mainly of iron and nickel (b/c of magnetic field (Ni), density of the earth, and space materials)
Earth is layered with respect to…
- Earth is layered with respect to both compositon and density.
- The volatiles that make up Earth’s hydrosphere and atmosphere came from volcanic degassing during differentiation.
Earth’s two heat engines
External (sun) and Internal (core)
External heat engine
- Circulates atmosphere and oceans
- Influences surficial (on earth’s surface) process (ex: weathering and erosion)
- Destructional process (breaks down land masses)