Earth Surface Science and its Origins Flashcards
How is the earth studied?
Through the study of its form, materials and history
Who is James Hutton?
- used empirical insight and deduction to create a radical theory of the earth
What were Hutton’s empirical inspiration?
1) Contemporary processes
2) Unconformities
Outline how Hutton used contemporary processes
- Looked at sedimentary rocks formed by incremental sedimentation and compaction
- Layers of earth - older at the Botton - superposition
- Immense periods of time needed to build
Outline how Hutton used unconformities
- Primitive rocks formed with molten materials - basalt
- Igneous rocks intrudes into sediment
- Intrusive rocks must be younger - cuts through old
- Violates principle of super position - cross cutting relationship
What are the 3 key principles of geology
1) original horizontally - sediment is laid out horizontally
2) Super position - youngest rock at the top of the pile
3) Cross cutting relationships - if a rock layer or fault cuts across another, the feature cut across must be older
What did Charles Lyell say about Hutton’s theory
- Advocate for it
- Book - principles of geology to prove gradualism
- Mountains etc did not form out of catastrophe, but a process that occurred over long periods of time through sediment build up
What is uniformitarianism?
- Lyell’s key contribution
- Assumption that the natural laws and processes that occur in present day scientific observations have always operated
What is geochronology?
- Branch of geology concerned with the age of rocks and date of events
- Many tried to guess the age of the earth
- Arthur Holmes used radiometric dating to guess age was 1.6 billion years
- Later found out it was 4.5 billion
Key earth facts
- 3rd planet away from the sun
- r = 6,535km
- Oblate spheroids - not actually spherical
- Rotates on spin axis - gravity is not only force
- Induces a centrifugal force that is not complete against gravity
- Induces force pointing towards equator - the bulge represents the balanced shape relative to these forces
What is the highest and lowest points on earth?
Highest - 8848m - Everest
Lowest - 10994m - Mariana Trench
What is the earths total relief
20,000m/20km
31% of earths surface is smooth
What is the interface zone?
- The interface between two driving physical systems
- Rocks put into motion by physiological processes
- Atmosphere put into motion by uneven solar heating
- studies how the earths surface responds to the changes in these drivers of change
Describe the core
- Solid, dense
- Composed of iron and nickel
- Inner and outer core
- Radius of 3470km
Describe the Mantle
- Split into 3 different sections
- Mesosphere, asthenosphere
- Fluid movement is important for plate tectonics
- 70% total mass of earth
- Radius of 2800km
