* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Layers of Earth
Survey
Document related concepts
Geomagnetic reversal wikipedia , lookup
Earth's magnetic field wikipedia , lookup
Schiehallion experiment wikipedia , lookup
Large igneous province wikipedia , lookup
Spherical Earth wikipedia , lookup
History of Earth wikipedia , lookup
Plate tectonics wikipedia , lookup
Future of Earth wikipedia , lookup
Age of the Earth wikipedia , lookup
History of geology wikipedia , lookup
History of geodesy wikipedia , lookup
Transcript
Layers of Earth Vocabulary For two-column notes, underlined titles are main ideas Showing the Layers of Earth There are four layers of the Earth. Draw this diagram Properties of Layers of Earth • • • Size Composition Temperature – Temperature increases with depth • Pressure – As you go deeper, the weight or rocks above increases – Pressure depends on the weight of rock above – So pressure increases with depth Layers of the Earth • Crust – Layer of solid rock 200°C to 400 °C that includes both dry land and ocean floor – 5-70 km thick – Continental crust (30-70 km) • Under continents • Composition - made of many types of rock, but mainly like granite – Oceanic crust (5-10 km) • Under oceans • Composition mainly like basalt • Thickness of oceanic crust less than continental – Both types "float" on the mantle Layers of the Earth • Oceanic crust - diagram Draw this diagram. Leave room to label the parts of the mantle and core Continental crust Oceanic crust Mantle Crust Layers of the Earth • Mantle – Makes up 2/3 of Earth's mass – Layer of hot (500 °C to 4,000 °C) but solid rock – Almost 3000 km thick – Divided into two parts • Upper mantle - Crust to 660 km – Rigid top plus crust form lithosphere (<200 km) – Asthenosphere just below lithosphere is “plastic” – Plastic means that a solid is able to flow • Lower mantle – 660 km - 2891 km Asthenosphere: below lithosphere Lower mantle Lithosphere crust and hard part of upper mantle Layers of the Earth • Core – Occupies center of planet – Almost 1/3 of Earth’s mass • Outer core - 4,030°C to 5400°C – 2258 km thick (3400 km radius) – Dense liquid nickel-iron • Inner core - 5400 °C – Radius of 1222 km – Solid iron – Would be liquid except for great pressure preventing atoms from spreading out The inner core The outer core How we know about the Earth’s structure • No one has been to the center of the Earth • We use information gathered from seismic waves (produced by earthquakes) to learn about the core of the Earth P-Wave shadow zone From the lack of S waves (which can’t pass through liquids) and a great slowing of the P wave velocity (by about 40%) it was deduced that the outer core is made of liquid. The shadow zone also defined the diameter of the core. Earth as a magnet • The source of the Earth’s magnetic field may be the liquid iron outer core. Iron is a good electric conductor. • The Earth’s magnetic field extends beyond the Earth The region of space affected by Earth’s magnetic field is the Magnetosphere Earth as a magnet • Magnetic versus geographic poles – The geographic poles of the Earth are located where the axis of rotation intersects the planet – The magnetic poles of the Earth are near the geographic poles – The magnetic poles wander over time – They also reverse from time to time (about every 70,000 years) – Note that the magnetic South Pole is in the Northern Hemisphere and the magnetic North Pole is in the Southern Hemisphere Shape of the Earth • The Earth is not a perfect sphere. • We know this by looking at the circumference (length around something round). Measured around the equator the circumference is 40,074 km Measured around the poles the circumference is 40,007 km Shape of the Earth • The Earth is an oblate spheroid (slightly squished sphere) • The spinning of the Earth on it’s axis causes the polar regions to flatten and the equatorial area to bulge. • The Earth is mostly smooth: the difference between the height of the tallest mountain and the deepest sea trench is only about 20 km. Classwork 1 – Layers of Earth Copy the questions into your notebook (right-side) and answer them 1. What part of the Earth’s core may be responsible for its magnetic field? 2. Name the three parts of the mantle and describe each 3. Where is the Earth’s South magnetic pole really located? 4. What part of the mantle is a plastic solid? 5. Which is thicker, the continental or oceanic crust? 6. What shape is the Earth?