record in the rock
DESCRIPTION
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 - PowerPoint PPT PresentationTRANSCRIPT
![Page 1: Record in the Rock](https://reader035.vdocuments.us/reader035/viewer/2022081502/5681659c550346895dd87677/html5/thumbnails/1.jpg)
Record in the Rock
What Processes Shape our Earth?
![Page 2: Record in the Rock](https://reader035.vdocuments.us/reader035/viewer/2022081502/5681659c550346895dd87677/html5/thumbnails/2.jpg)
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 Makes life better through application of
technology
![Page 3: Record in the Rock](https://reader035.vdocuments.us/reader035/viewer/2022081502/5681659c550346895dd87677/html5/thumbnails/3.jpg)
![Page 4: Record in the Rock](https://reader035.vdocuments.us/reader035/viewer/2022081502/5681659c550346895dd87677/html5/thumbnails/4.jpg)
![Page 5: Record in the Rock](https://reader035.vdocuments.us/reader035/viewer/2022081502/5681659c550346895dd87677/html5/thumbnails/5.jpg)
Layers of the Earth Characterized by a gradual increase in
temperature, pressure, and density with depth Inner Core: solid; composed mainly of nickel
and iron Outer Core: hot liquid made of nickel and iron Mantle: thick layer; plasma; denser than crust Crust: thin layer of silicates; two kinds of
crusts- Oceanic Crust: Older, thicker, less dense,
granite Continental Crust: Thin, younger, denser, basalt
![Page 6: Record in the Rock](https://reader035.vdocuments.us/reader035/viewer/2022081502/5681659c550346895dd87677/html5/thumbnails/6.jpg)
![Page 7: Record in the Rock](https://reader035.vdocuments.us/reader035/viewer/2022081502/5681659c550346895dd87677/html5/thumbnails/7.jpg)
Lithosphere: crust and upper part of the mantle (plate)
Asthenosphere: part of mantle; less rigid than the lithosphere; convection currents flow here
![Page 8: Record in the Rock](https://reader035.vdocuments.us/reader035/viewer/2022081502/5681659c550346895dd87677/html5/thumbnails/8.jpg)
Age of the Earth Kelvin Method:
Assumed earth was hot molten rock he measured rate of earth’s cooling to present Took into account heat coming from the sun and
from within the earth Problem: was not aware of radioactivity
Measured radioactive decay of Uranium 238 Lead 206
Estimated Earth as 4.6 Billion Years old
![Page 9: Record in the Rock](https://reader035.vdocuments.us/reader035/viewer/2022081502/5681659c550346895dd87677/html5/thumbnails/9.jpg)
Radiometric Dating Henri Bequerel discovered the
radioactive element 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! Examples:
Nonliving: 3.9 billion year old rock of Uranium 238 Lead 206
Living: Carbon 14 Carbon 12
![Page 10: Record in the Rock](https://reader035.vdocuments.us/reader035/viewer/2022081502/5681659c550346895dd87677/html5/thumbnails/10.jpg)
Radioactive Half-Life (t1/2 ):
The time for half of the radioactive substances in a given sample to undergo decay.
After one half life there is 1/2 of original sample left.
After two half-lives, there will be 1/2 of the 1/2 = 1/4 the original sample.
![Page 11: Record in the Rock](https://reader035.vdocuments.us/reader035/viewer/2022081502/5681659c550346895dd87677/html5/thumbnails/11.jpg)
Example 1You have 100 g of radioactive C-14. The
half-life of C-14 is 5730 years. How many grams are left after one half-
life? Answer:50 g How many grams are left after two half-lives?
![Page 12: Record in the Rock](https://reader035.vdocuments.us/reader035/viewer/2022081502/5681659c550346895dd87677/html5/thumbnails/12.jpg)
Example 2 The half-life of iodine-131 is 8 days. If you start with 36 grams of I-131, how
much will be left after 24 days?
36 g 1 half-life 8 days 18 g 18 g 2 half-lives 16 days 9 g 9 g 3 half-lives 24 days 4.5 g
![Page 13: Record in the Rock](https://reader035.vdocuments.us/reader035/viewer/2022081502/5681659c550346895dd87677/html5/thumbnails/13.jpg)
Types of Relative Dating Relative Dating:
Finding the age of something compared to something else
1. Law of Superposition- the bottom layer of an undisturbed section is older than the top
![Page 14: Record in the Rock](https://reader035.vdocuments.us/reader035/viewer/2022081502/5681659c550346895dd87677/html5/thumbnails/14.jpg)
2. Original Horizontality- soil is deposited horizontally (fall to bottom) then form rock layers
![Page 15: Record in the Rock](https://reader035.vdocuments.us/reader035/viewer/2022081502/5681659c550346895dd87677/html5/thumbnails/15.jpg)
3. Lateral Continuity- layers of sediment extend in all directions when they form
![Page 16: Record in the Rock](https://reader035.vdocuments.us/reader035/viewer/2022081502/5681659c550346895dd87677/html5/thumbnails/16.jpg)
4. Law of Cross-Cutting Relationships- Folds and faults are younger than the layers that they cut across
![Page 17: Record in the Rock](https://reader035.vdocuments.us/reader035/viewer/2022081502/5681659c550346895dd87677/html5/thumbnails/17.jpg)
5. Inclusions- the inclusions (rock pieces) are older than the surrounding rock
![Page 18: Record in the Rock](https://reader035.vdocuments.us/reader035/viewer/2022081502/5681659c550346895dd87677/html5/thumbnails/18.jpg)
6. Faunal Succession- fossils can be used to identify relative age of layers of rock
![Page 19: Record in the Rock](https://reader035.vdocuments.us/reader035/viewer/2022081502/5681659c550346895dd87677/html5/thumbnails/19.jpg)
-Index Fossil- 1. lived in a certain time span in many places2. lived in great numbers3. distinct features to identify
-Correlation- matching rocks by Index Fossil in different places
![Page 20: Record in the Rock](https://reader035.vdocuments.us/reader035/viewer/2022081502/5681659c550346895dd87677/html5/thumbnails/20.jpg)
![Page 21: Record in the Rock](https://reader035.vdocuments.us/reader035/viewer/2022081502/5681659c550346895dd87677/html5/thumbnails/21.jpg)
Alfred Wegener Believed in the
theory called “continental drift”
The supercontinent (Pangea) split into pieces, then moved to different positions
![Page 22: Record in the Rock](https://reader035.vdocuments.us/reader035/viewer/2022081502/5681659c550346895dd87677/html5/thumbnails/22.jpg)
Support a system of under water mountain chains or
mid-ocean ridges, rise thousands of meters above the ocean floor.
Youngest ocean floor rocks-near the mid-ocean ridge.
Oldest near the edges of the ocean basins When the seafloor reaches a continental
boundary, it is forced downward beneath the continent called the seafloor trench
continent
old
Mid-ocean ridge
young old
Seafloor & trench
continent
![Page 23: Record in the Rock](https://reader035.vdocuments.us/reader035/viewer/2022081502/5681659c550346895dd87677/html5/thumbnails/23.jpg)
Plate Tectonics Plates- crust that extends into the upper part of the
mantle. Upper part of the mantle is called the lithosphere. The bottom part of the lithosphere that is a plastic like
zone is called the asthenosphere.
Mid-ocean ridgeContinental
CrustOcean Crust Ocean Crust
ContinentalCrust
lithosphere
Convection Current
![Page 24: Record in the Rock](https://reader035.vdocuments.us/reader035/viewer/2022081502/5681659c550346895dd87677/html5/thumbnails/24.jpg)
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!
Plate Tectonics Theory
There are 3 types of plate boundaries:1. divergent2. convergent3. transform
![Page 25: Record in the Rock](https://reader035.vdocuments.us/reader035/viewer/2022081502/5681659c550346895dd87677/html5/thumbnails/25.jpg)
-Earth has 6 major plates and many small ones.
1. Eurasian 4. North American
2. Pacific 5. South American
3. African 6. Antarctic
![Page 26: Record in the Rock](https://reader035.vdocuments.us/reader035/viewer/2022081502/5681659c550346895dd87677/html5/thumbnails/26.jpg)
Plate Boundaries1. Divergent- two plates move apart.
Example- seafloor spreading at the Mid-ocean ridge. (6 cm per year)
![Page 27: Record in the Rock](https://reader035.vdocuments.us/reader035/viewer/2022081502/5681659c550346895dd87677/html5/thumbnails/27.jpg)
Plate Boundaries2. Transform- plates move past one another in opposite directions or in the same direction at different speeds
Example- San Andreas fault
![Page 28: Record in the Rock](https://reader035.vdocuments.us/reader035/viewer/2022081502/5681659c550346895dd87677/html5/thumbnails/28.jpg)
Plate Boundaries3. Convergent- two plates collide
-There are 3 types of plate boundaries
![Page 29: Record in the Rock](https://reader035.vdocuments.us/reader035/viewer/2022081502/5681659c550346895dd87677/html5/thumbnails/29.jpg)
Convergent Platesa.Two ocean plates collide- the edge of one is
bent downwards.- Regions where the plates descend are
called subduction zone- May form volcanoes or islands (island arc)
![Page 30: Record in the Rock](https://reader035.vdocuments.us/reader035/viewer/2022081502/5681659c550346895dd87677/html5/thumbnails/30.jpg)
Convergent Platesb. Oceanic and continental plates collide- the denser oceanic plate descends into the athenosphere.
- may form chain of volcanic mountains
- Earthquakes are common
![Page 31: Record in the Rock](https://reader035.vdocuments.us/reader035/viewer/2022081502/5681659c550346895dd87677/html5/thumbnails/31.jpg)
Convergent Platesc. Two continental plates collide- the continental rocks buckle and rise.
- mountain chains form
- earthquakes are common
- very little volcanic activity
-continental motion
occurs (1-5 cm per year)
![Page 32: Record in the Rock](https://reader035.vdocuments.us/reader035/viewer/2022081502/5681659c550346895dd87677/html5/thumbnails/32.jpg)
![Page 33: Record in the Rock](https://reader035.vdocuments.us/reader035/viewer/2022081502/5681659c550346895dd87677/html5/thumbnails/33.jpg)
Convection Currents
![Page 34: Record in the Rock](https://reader035.vdocuments.us/reader035/viewer/2022081502/5681659c550346895dd87677/html5/thumbnails/34.jpg)
HOT Spots
Stationary plumes of hot material that initiate at the core/mantle interface
Hawaii: the plume is beneath oceanic crust
![Page 35: Record in the Rock](https://reader035.vdocuments.us/reader035/viewer/2022081502/5681659c550346895dd87677/html5/thumbnails/35.jpg)
Hot Spots Yellowstone is associated with a hot spot under
continental crust
![Page 37: Record in the Rock](https://reader035.vdocuments.us/reader035/viewer/2022081502/5681659c550346895dd87677/html5/thumbnails/37.jpg)
![Page 38: Record in the Rock](https://reader035.vdocuments.us/reader035/viewer/2022081502/5681659c550346895dd87677/html5/thumbnails/38.jpg)