Record in the Rock. What Processes Shape our Earth?. Earth Science- the study of earth and space Importance of Earth Science: Contributes to our knowledge of the world Understanding forces that shape our earth can better forecast potential disasters Provides valuable resources
What Processes Shape our Earth?
Importance of Earth Science:
Asthenosphere: part of mantle; less rigid than the lithosphere; convection currents flow here
Radioactive Decay: when elements break down
Radiometric Dating: rate at which radioactive decay takes place
Based on half-life (time to take ½ of element to decay)
Radioactive decay rates don’t change!
Nonliving: 3.9 billion year old rock of Uranium 238 Lead 206
Living: Carbon 14 Carbon 12Radiometric Dating
1/2 of the 1/2 = 1/4 the original sample.
You have 100 g of radioactive C-14. The half-life of C-14 is 5730 years.
are left after two
Law of Superposition- the bottom layer of an undisturbed section is older than the topTypes of Relative Dating
1. lived in a certain time span in many places
2. lived in great numbers
3. distinct features to identify
-Correlation- matching rocks by Index Fossil in different places
Seafloor & trench
A relatively recent theory that the Earth's crust is composed of rigid plates that move relative to one another.
Plate movements are on the order of a few centimeters/year - about the same rate as your fingernails grow!
There are 3 types of plate boundaries:
1. Eurasian 4. North American
2. Pacific 5. South American
3. African 6. Antarctic
2. Transform- plates move past one another in opposite directions or in the same direction at different speeds
Example- San Andreas fault
3. Convergent- two plates collide
-There are 3 types of plate boundaries
b. Oceanic and continental plates collide- the denser oceanic plate descends into the athenosphere.
- may form chain of volcanic mountains
- Earthquakes are common
c. Two continental plates collide- the continental rocks buckle and rise.
- mountain chains form
- earthquakes are common
- very little volcanic activity
occurs (1-5 cm per year)