Download Inside Earth: Chapter 1

Inside Earth: Chapter 1
Plate Tectonics
Section 1: Earth’s Interior
Quick Facts & Figures
• What if you could drive to the center of Earth?
How long would the drive be?
– At 62 miles per hour:
• Half an hour to make it through most of the crust
• About an additional 29 hours to drive through most of the
mantle
• Then an additional 35 hours to drive to the center of the
core.
• 64.5 hours or about 2 ½ days! That’s about the time it
would take to drive from here to Disney World.
Forces that change the surface:
• Constructive Forces: processes that help build up the
Earth, either by depositing soil or silt in a river, or by
volcanoes and lava flows that generates new land.
– Examples:
• Volcanic islands, sand dunes, river deltas
• Link
• Destructive Forces: processes that break down the
Earth, either through the violent actions of volcanoes
and earthquakes or by the steady flow of a river.
– Examples:
• Erosion, weathering, glaciers, volcanoes, earthquakes
• Link
Constructive vs Destructive Forces
What’s Inside?
Scientists need to use both DIRECT and INDIRECT
EVIDENCE
• Direct:
– Volcanic rocks, faults, erosion
– Experimental rocks, meteorites
• Indirect:
– Seismic waves, mass balancing, meteorites, orbital
considerations
• Interactive link
Depth vs Pressure
S waves vs P waves
The Crust
• Includes soil, rock, mountains, and water
• Thinner than mantle & core areas
• Thinnest beneath the ocean; thickest under high
mountains. Ranges from 5-40 km thick.
• Oceanic crust consists of dense rock like basalt
• Continental crust consists of less dense rock like
granite.
• At some convergent boundaries, oceanic crust
gets pulled under continental crust. This is called
a subduction zone.
Granite vs. Basalt
The Mantle
• The uppermost part of the mantle and crust
together form a rigid layer called the lithosphere.
It averages about 100 km thick.
• Heat and pressure continue to increase making
the area just below the lithosphere less rigid and
flows slowly. The material is like soft road tar and
bends like plastic. This layer is called the
asthenosphere.
• Beneath the asthenosphere, solid mantle
material extends to the Earth’s core.
• Mantle is nearly 3,000 km thick in all.
Asthenosphere vs Lithosphere
What about the mesosphere?
• Sometimes the part of the mantle between
the asthenosphere and the outer core is
referred to as the mesosphere.
• Don’t confuse it with the layer in the earth’s
atmosphere between the stratosphere and
the thermosphere…also
called the mesosphere.
Prefixes can help…
• Asthenophere = astheno-, from Greek
asthenēs “weak”
• Lithosphere = form of Greek lithos "stone“
• Mesosphere = from Greek mesos 'middle'
The Core
• Consists of two parts:
– Outer core:
• molten metal that surrounds the inner core
• Behaves like a thick liquid
– Inner core:
• Dense ball of solid metal
• Extreme pressure squeezes the atoms of iron and nickel so
much they cannot spread out and become liquid
– Thickness = about 3,500 km
– Estimated temperature = about 2,000 C to 5,000 C (as
hot as the sun’s surface!)
Earth’s Magnetic Field
• Currents in the liquid outer core force the solid
inner core to spin at a slightly faster rate than the
rest of the planet. This movement causes the
planet to act like a giant bar magnet.
• The magnetic poles are NOT in the same location
as the geographic poles.
• Link to more information
• Link to compass interactive
• Link to unitedstreaming clip