Earth: From Core to Crust Chapter 2. Reading the Geologic Record The difference between geologist...
-
Upload
janel-stevenson -
Category
Documents
-
view
217 -
download
0
Transcript of Earth: From Core to Crust Chapter 2. Reading the Geologic Record The difference between geologist...
![Page 1: Earth: From Core to Crust Chapter 2. Reading the Geologic Record The difference between geologist and historians is that historians think of history over.](https://reader035.fdocuments.us/reader035/viewer/2022062803/56649f255503460f94c3beae/html5/thumbnails/1.jpg)
Earth: From Core to CrustEarth: From Core to Crust
Chapter 2Chapter 2
![Page 2: Earth: From Core to Crust Chapter 2. Reading the Geologic Record The difference between geologist and historians is that historians think of history over.](https://reader035.fdocuments.us/reader035/viewer/2022062803/56649f255503460f94c3beae/html5/thumbnails/2.jpg)
Reading the Geologic RecordReading the Geologic Record
• The difference between geologist and historians is that historians think of history over a period on thousands of years and geologists over billions of years.
• The time frames that geologists talk about are referred to as either absolute or relative.– Relative time – refers to an event that happens before
or after another event– Absolute time – the exact time
![Page 3: Earth: From Core to Crust Chapter 2. Reading the Geologic Record The difference between geologist and historians is that historians think of history over.](https://reader035.fdocuments.us/reader035/viewer/2022062803/56649f255503460f94c3beae/html5/thumbnails/3.jpg)
Three Basic Principles to Read the Three Basic Principles to Read the Geologic RecordGeologic Record
• Geologic Record uses relative time to date the features of the earth.
• James Hutton came up with three principles that lead to the creating of the Geologic Record.
• Three principles help Geologists figure out what happened and when:
1. Superposition
2. Uniformitarianism
3. Fossil Correlation
![Page 4: Earth: From Core to Crust Chapter 2. Reading the Geologic Record The difference between geologist and historians is that historians think of history over.](https://reader035.fdocuments.us/reader035/viewer/2022062803/56649f255503460f94c3beae/html5/thumbnails/4.jpg)
1. Superposition1. Superposition
• New sediments are deposited over old ones.
• Therefore the lower the layer of undisturbed rock the older it is.
![Page 5: Earth: From Core to Crust Chapter 2. Reading the Geologic Record The difference between geologist and historians is that historians think of history over.](https://reader035.fdocuments.us/reader035/viewer/2022062803/56649f255503460f94c3beae/html5/thumbnails/5.jpg)
2. Uniformitarianism2. Uniformitarianism
• This principle is based on the idea that natural processes occur in the same way today as they did in the past
• For example a river would flow the same way and cause the same type of erosion and deposition
• This is important because when geologists study ancient layer of earth and their appearance they can make assumptions based on processes occurring on earth today.
![Page 6: Earth: From Core to Crust Chapter 2. Reading the Geologic Record The difference between geologist and historians is that historians think of history over.](https://reader035.fdocuments.us/reader035/viewer/2022062803/56649f255503460f94c3beae/html5/thumbnails/6.jpg)
3. Fossil Correlation3. Fossil Correlation
• Fossils are organic plant and animal matter that has decomposed and been removed and replaced by minerals in solution
• This principle is based on the idea that different rock deposits that contain the same fossil types must be the same age.
• By looking at the fossils in different layers of rock geologists can determine when certain animal appeared and disappeared.
• Approximate climates can also be determined.
![Page 7: Earth: From Core to Crust Chapter 2. Reading the Geologic Record The difference between geologist and historians is that historians think of history over.](https://reader035.fdocuments.us/reader035/viewer/2022062803/56649f255503460f94c3beae/html5/thumbnails/7.jpg)
3. Fossil Correlation3. Fossil Correlation
![Page 8: Earth: From Core to Crust Chapter 2. Reading the Geologic Record The difference between geologist and historians is that historians think of history over.](https://reader035.fdocuments.us/reader035/viewer/2022062803/56649f255503460f94c3beae/html5/thumbnails/8.jpg)
Layers Beneath our FeetLayers Beneath our Feet
• As the earth formed the heavier material settled in the center and the lighter material on top.
• We cannot drill holes to the center of the earth because of the distance and heat so we rely on seismology to gain information on the layers.
![Page 9: Earth: From Core to Crust Chapter 2. Reading the Geologic Record The difference between geologist and historians is that historians think of history over.](https://reader035.fdocuments.us/reader035/viewer/2022062803/56649f255503460f94c3beae/html5/thumbnails/9.jpg)
SeismologySeismology
• A seismograph records the earth’s vibrations when there is an earthquake.
• As the ground shakes different waves are generated.
• These waves act differently depending on the material that it passes through
![Page 10: Earth: From Core to Crust Chapter 2. Reading the Geologic Record The difference between geologist and historians is that historians think of history over.](https://reader035.fdocuments.us/reader035/viewer/2022062803/56649f255503460f94c3beae/html5/thumbnails/10.jpg)
Types of WavesTypes of Waves
• There are two types of waves that pass through the earth.– Primary Waves (P waves) – squeeze and
stretch the material they pass through. They pass through any type of material and move very quickly.
– Secondary Waves (S waves) – vibrate at right angles to P waves and only travel through solids
![Page 11: Earth: From Core to Crust Chapter 2. Reading the Geologic Record The difference between geologist and historians is that historians think of history over.](https://reader035.fdocuments.us/reader035/viewer/2022062803/56649f255503460f94c3beae/html5/thumbnails/11.jpg)
Types of WavesTypes of Waves
![Page 12: Earth: From Core to Crust Chapter 2. Reading the Geologic Record The difference between geologist and historians is that historians think of history over.](https://reader035.fdocuments.us/reader035/viewer/2022062803/56649f255503460f94c3beae/html5/thumbnails/12.jpg)
Gutenberg DiscontinuityGutenberg Discontinuity
• An interesting thing happens at about 2,900 Km below the surface.– The P waves slow right down and the S
waves stop completely
• From readings that Beno Gutenberg took (1914) he figured out that this is the depth at which the liquid core begins.
![Page 13: Earth: From Core to Crust Chapter 2. Reading the Geologic Record The difference between geologist and historians is that historians think of history over.](https://reader035.fdocuments.us/reader035/viewer/2022062803/56649f255503460f94c3beae/html5/thumbnails/13.jpg)
Layers of the EarthLayers of the Earth
![Page 14: Earth: From Core to Crust Chapter 2. Reading the Geologic Record The difference between geologist and historians is that historians think of history over.](https://reader035.fdocuments.us/reader035/viewer/2022062803/56649f255503460f94c3beae/html5/thumbnails/14.jpg)
The CoreThe Core
• Makes up a third of the total mass of the planet
• Made up of two parts – the inner and the outer
• Inner Core– Made mostly of iron– Temperatures range from 4000 C to 6650 C (hotter than the sun)– It is solid because of the immense pressure
• Outer Core– Not as much pressure so this layer is liquid– Generates our magnetic field– Made up mostly of iron – This layer begins about 5,200 Km below earth’s surface
![Page 15: Earth: From Core to Crust Chapter 2. Reading the Geologic Record The difference between geologist and historians is that historians think of history over.](https://reader035.fdocuments.us/reader035/viewer/2022062803/56649f255503460f94c3beae/html5/thumbnails/15.jpg)
The MantelThe Mantel
• Takes up 80% of earth’s total volume
• Made up of iron, silicone and magnesium
• Divided into two parts – Lower and Upper
• Lower Mantel– Starts at 2,900 km below surface and ends
about 500 km below– Moving towards the surface the temperature
gradually cools.
![Page 16: Earth: From Core to Crust Chapter 2. Reading the Geologic Record The difference between geologist and historians is that historians think of history over.](https://reader035.fdocuments.us/reader035/viewer/2022062803/56649f255503460f94c3beae/html5/thumbnails/16.jpg)
The MantelThe Mantel
![Page 17: Earth: From Core to Crust Chapter 2. Reading the Geologic Record The difference between geologist and historians is that historians think of history over.](https://reader035.fdocuments.us/reader035/viewer/2022062803/56649f255503460f94c3beae/html5/thumbnails/17.jpg)
Upper Mantel – AsthenosphereUpper Mantel – Asthenosphere• This layer of the earth is responsible for many of
the processes that cause the crust to look the way it does.
• Hot spots in this layer create convection currents that move the earth’s tectonic plates
• When volcanoes erupt the magma that forms this layer of the earth can flow out on to the surface as lava.
![Page 18: Earth: From Core to Crust Chapter 2. Reading the Geologic Record The difference between geologist and historians is that historians think of history over.](https://reader035.fdocuments.us/reader035/viewer/2022062803/56649f255503460f94c3beae/html5/thumbnails/18.jpg)
Moho DiscontinuityMoho Discontinuity
• Discovered by Andrija Mohorovicic
• This is a depth where there is a sharp increase in the speed of waves
• This discontinuity form the boundary between the asthenosphere and the crust
![Page 19: Earth: From Core to Crust Chapter 2. Reading the Geologic Record The difference between geologist and historians is that historians think of history over.](https://reader035.fdocuments.us/reader035/viewer/2022062803/56649f255503460f94c3beae/html5/thumbnails/19.jpg)
CrustCrust
• Very thin covering on the surface of the earth• Makes up only 0.1% of earth’s total volume• Made up of two parts:
– sima - beneath the ocean, made up of basaltic rock (iron, magnesium and silica)
– sial – makes up the continents, contains many more minerals (silica, potassium, aluminum to name a few), it’s thicker than the sima
![Page 20: Earth: From Core to Crust Chapter 2. Reading the Geologic Record The difference between geologist and historians is that historians think of history over.](https://reader035.fdocuments.us/reader035/viewer/2022062803/56649f255503460f94c3beae/html5/thumbnails/20.jpg)
Sima Sial