Transcript Divided into three layers based on composition

The Dynamic Earth
Chapter 3
Earth consists of:
 Rock – geosphere
 Air – Atmosphere
 Water – hydrosphere
 Living things (organisms) - biosphere
The Earth as a System
Geosphere
 All the rock that makes up the
solid part of the Earth and all of
the loose rock and soil on the
Earth’s surface
Geosphere
 Divided into three layers based on composition:
 Crust – thin, outermost layer (lowest density)
 Mantle – next layer, made up of rocks of
medium density
 Core – center and innermost layer, made up of
the highest density
 Divided into five layers based on physical
structure:
 Lithosphere – outer layer, rigid, includes crust
and upper mantle, divided into pieces called
tectonic plates.
 Asthenosphere – made of the mantle, solid,
flexible and made of rock, allows plates to
move on top of it.
Geosphere Five layers continued…
 Mesosphere – lowest part of the mantle
 Outer core – dense liquid layer
 Inner core – dense, solid and extremely hot
 See figure 3, page 65
Earth’s Layers
Plate tectonics
 Definition: is the movement of large pieces
of the lithosphere (plates) on top of the
asthenosphere
 Continents are located on top of plates and
move along with them.
Major Plates:
 North America
 Pacific
 South America
 African
 Eurasian
 Antarctic
 See figure 4, page 66
Tectonic Plates
Most geologic activity takes place at the
point where two plates meet – plate
boundaries (faults)
 Collisions cause the crust to be pushed up forming
mountains
 Earthquakes - cause breaks in the rock at faults which
causes vibrations in the crust
 Magnitude of an earthquake is the amount of NRG released
and this is measured by the Richter scale.
 The smaller the magnitude of the vibration, the weaker the
earthquake.
 See Figure 6, page 67
Where do Earthquakes
Occur?
Plates continued…
 Movements of the plates can cause molten rock or
magma to flow upward through a volcano
 Volcanoes put large amounts of very hot ash, gasses
and dust into the air
 Can reduce the amount of sunlight reaching Earth’s
surface for long periods of time causing
temperatures to drop over large areas.
 See Figure 7, page 68
Volcanoes: The Ring of Fire
 Erosion: the removal and transport of
materials on Earth’s surface.
 Caused by two main agents:
 Wind
 Water
Atmosphere
 Mixture of gases that surround the Earth and
insulates the surface
 Made up of 78% - Nitrogen, 21% - Oxygen, 1% - other
gases and tiny solid particles called atmospheric
dust.
 Pulled toward the surface by gravity and is denser
near the Earth’s surface
Divided into four layers based on
temperature and distance from the
surface:
 Troposphere – layer closest to surface, densest
layer, most weather occurs here, temperatures
decrease as altitude increases.
 Stratosphere – next layer, temperatures increase as
altitude increases, contains ozone layer which
blocks sun’s UV rays
Atmosphere layers continued…
 Mesosphere – next layer, coldest layer.
 Thermosphere – uppermost layer, highest
temperatures, lowest part is called ionosphere.
Layers of the Atmosphere
Energy comes from sun and into the
atmosphere and:
 5% is reflected by Earth’s surface
 20% is absorbed by clouds, ozone, and
atmospheric gases
 25% is scattered and reflected by clouds and air
 50% is absorbed by the Earth’s surface
Energy is transferred through the
atmosphere in three different ways:
 Radiation – transfer of NRG across space
 Convection – transfer of heat by air currents
 Conduction – flow of heat from a warmer object to
a colder object by direct contact
Energy Transfer in the
Atmosphere
Greenhouse effect
 Certain gases in the atmosphere (greenhouse
gases) absorb some of the heat reflected by the
surface preventing it from escaping back into
space.
 Without it, Earth too cold for life
 Major greenhouse gases – carbon dioxide,
methane, nitrous oxide and water vapor
The Greenhouse Effect
Hydrosphere
 Includes all water on or near Earth’s surface
 Water or Hydrologic Cycle – the continuous
movement of water into air, onto land, and back into
water sources.
Made up of three major processes:
 Evaporation – changing of a liquid into a gas-water to
water vapor (occurs at the surface)
 Condensation – changing of a gas into a liquid
 Precipitation – water that falls from clouds in any form
ex rain, snow, etc.
 See Figure 17, page 77
The Water Cycle
Two major types of water:
 Salt water or oceans
 97% of all Earth’s water is here
 Contains salts (mostly sodium chloride) that have been
dissolved out of rock, carried by rivers or come from
volcanic eruptions
 Average salinity – concentrations of salts is 3.5%
Four major oceans
 Indian
 Atlantic
 Pacific (largest, deepest)
 Artic (smallest)
 Actually all joined into one world ocean
 Covers 70% of Earth’s surface
 See Figure 18, page 79
Earth’s Oceans
Oceans
 Divided into zones based on temperature:
 Surface – warm, top layer
 Thermocline – middle layer where temperature drops
rapidly with depth
 Deep Zone – bottom layer, extremely cold, no light
Oceans continued…
 Ocean regulates world temperature by absorbing
and storing sun’s NRG and then moving the NRG
around using currents
 Without this temperature regulation, Earth’s
temperatures would be too extreme to support life.
Oceans continued…
 Surface currents – stream like movements of water
near the surface, driven by the wind, can be warm or
cold and they don’t mix easily.
 Deep currents – stream like movements of water near
the bottom of the ocean, form when cold dense water
drops below warmer less dense water, flow extremely
slow
Temperature Zones
Fresh Water
 Lakes, rivers, wetlands, groundwater, glaciers and
ice caps
 3% of all water
 Most in ice caps and glaciers
 Rivers – flowing water
 Lakes – standing water
 Groundwater – water that trickled down through the
soil and rock
Groundwater continued…
 Collects in aquifers – rock layers that
surround and collect groundwater
 Recharge areas – land that supplies
groundwater to an aquifer
 See Figure 24, page 83
Aquifers
Biosphere
 Layer of Earth which supports life
 Very thin
 Extends 12 km below the ocean and 9 km into the
atmosphere
 Most life requires:
 Liquid water
 Moderate temperatures
 NRG source (food)
 Continuous recycling of all needed materials
 Gravity
 All NRG for life supplied originally by the sun and is
transferred up the food chain
 Plants use light NRG to make food; plant is eaten by
an animal and that is eaten by another animal, etc.
 At each step in the food chain some NRG is used and
lost, only about 10% goes onto the next step
 Earth is a closed system – NRG can enter (light)
and leave (heat), but matter cannot