1. GEOL 120: Planet Earth Dr. James R. Ebert Dennison 23 X3065

2. Seven “Big Ideas” about our Earth

3. Seven “Big Ideas” about our Earth
Earth can be described as a system of interacting “spheres” and processes.
Energy is transferred within and between spheres.
Earth’s surface is constantly changed by
Interior processes
Surface processes

4. Seven “Big Ideas” about our Earth
Changes occur over vast expanses of time.
Materials are transferred within and between spheres in a massive version of “recycling.”
Life has a long history of interacting with and changing Earth.
Geologists use multiple methods to understand Earth processes and products.

5. Geosphere – Earth’s rocky portion
1) Earth can be described as a system of interacting “spheres” and processes.
Geosphere – Earth’s rocky portion
Lithosphere: Crust and uppermost Mantle
Mantle
Outer and Inner Cores
Hydrosphere – Earth’s water
Atmosphere – Earth’s air
Biosphere – Life on and in Earth
Cryosphere – Earth’s ice

6. 2) Energy is transferred within and between spheres.
Heat Energy is the most important type
Conduction – direct transfer of heat by contact
Radiation – transfer of heat across a distance without direct contact
Convection – transfer of heated material from place to place through gravity acting on differences in density of the materials

7. 3) Earth’s surface is constantly changed by Interior Processes
Movement of lithospheric plates
Formation of ocean basins
Formation of igneous rock
Formation of Mountains
Formation of metamorphic rock
Rates may be
Slow – movement of plates
Rapid – earthquakes, volcanic eruptions

8. 3) Earth’s surface is constantly changed by Surface Processes
Weathering – breakdown of rock
Erosion – movement of rock fragments
Deposition – settling of moving fragments
Formation of sedimentary rocks

9. 4) Changes occur over vast expanses of time.
Earth is ancient
Planet formed 4.6 billion years ago
Earth processes produce recognizable products
These products provide evidence for past operation of processes
Even slow processes can produce great changes over great lengths of time

10. 4) Changes occur over vast expanses of time.
Sequences or histories of these processes can be compiled from across the Earth
Fossils are very useful for determining relative ages
Numerical ages can be determined
Radioactive decay provides numerical ages for rocks that contain radioactive elements

11. 5) Materials are transferred within and between spheres in a massive version of “recycling.”
Law of Conservation of Matter
Matter can neither be created nor destroyed
Matter can be changed from one form into another
Water is recycled among the hydrosphere, atmosphere, lithosphere and cryosphere
Gasses are recycled among the atmosphere, hydrosphere and lithosphere
Rocks are recycled in the lithosphere with help from Earth’s interior heat and from circulation in the hydrosphere

12. 6) Life has a long history of interacting with and changing Earth.
Life appeared on Earth at least 3.8 billion years ago
Life has changed through time (evolution) as documented by fossils
The biosphere depends on the lithosphere, hydrosphere and atmosphere
The biosphere modifies these other spheres through life processes acting over long periods of time

13. 7) Geologists use multiple methods to understand Earth processes and products.
Earth is a complex planet and must be studied at various scales
Satellite remote sensing, seismic imaging, regional mapping using GPS and GIS, single outcroppings, hand samples, thin sections, scanning electron micrographs
Owing to tremendous scale, both spatial and temporal, we use models, simulations, etc. to study some processes
We use quantitative, qualitative, experimental and deductive methods to study Earth

14. 7) Geologists use multiple methods to understand Earth processes and products.
Modern processes provide analogies to help understand ancient products
Ancient products provide insights into the workings of modern processes
Everything we know about Earth, like all scientific knowledge, is subject to revision as we learn more

15. Seven “Big Ideas” about our Earth
Earth can be described as a system of interacting “spheres” and processes.
Energy is transferred within and between spheres.
Earth’s surface is constantly changed by
Interior processes
Surface processes
Changes occur over vast expanses of time.
Materials are transferred within and between spheres in a massive version of “recycling.”
Life has a long history of interacting with and changing Earth.
Geologists use multiple methods to understand Earth processes and products.