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Amazing Earth

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Title: Rocks and Minerals Author: Rebecca Franz Last modified by: Leander ISD Created Date: 7/31/2009 6:09:58 PM Document presentation format: On-screen Show (4:3) – PowerPoint PPT presentation

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Title: Amazing Earth


1
Amazing Earth
2
Objectives
  • Analyze and predict the sequence of events in the
    rock cycle.
  • Predict land features resulting from gradual
    changes such as mountain building, beach erosion,
    land subsidence, and continental drift.

3
Rocks
  • Solid mixtures of one or more minerals.
  • Classified by how they formed.
  • Three types of Rocks
  • Igneous
  • Sedimentary
  • Metamorphic

4
Three Types of Rock
5
Igneous Rock
  • Forms when hot liquid rock, or magma, cools and
    hardens.

6
Extrusive Igneous Rock
  • Forms on the Earths surface
  • Cools quickly
  • Contains very small crystals or none at all

7
Intrusive Igneous Rock
  • Forms when magma cools beneath the surface of the
    Earth
  • Cools very slowly, forms crystals and is usually
    very coarse

8
Sedimentary Rock
  • Forms when pieces of rocks or minerals called
    Sediment are compacted and or cemented
    together.
  • Forms at or near the surface of the Earth.
  • Consist of layers called strata.

9
Formation of Sediment
  • Uplift rising of the Earths crust.
  • Weathering the break down of rock into smaller
    pieces (sediment - sand, soils, gravel,etc..)
  • Physical vs. Chemical Weathering
  • Physical/mechanical - physical breakdown through
    direct contact of heat, water, ice, and pressure.
  • Chemical - chemical breakdown by water, acids,
    and other chemicals that change the chemical
    composition.
  • Erosion the movement of broken pieces of rock
    and sediment from one place to another by water,
    wind, gravity and other forces.

10
Formation of Sedimentary Rock
  • Compaction layered sediment is squeezed or
    compacted together until it hardens into new
    rock.
  • Cementation dissolved minerals in the water
    separates out to form a natural glue that binds
    sediments together.

11
Types of Sedimentary Rock
  • Clastic - Forms when rock or mineral fragments
    are cemented together and forms clasts
    (conglomerate and sandstone)
  • Chemical Forms when minerals crystallized out
    of a solution of minerals and water (Halite).
  • Organic Forms from the remains of living things
    (shells or skeletons) Limestone.

12
The Rock Cycle
  • The continual process by which new rock is formed
    from old rock material

13
Rock CycleAnimation
14
Erosion and Weathering Review
15
Beach Erosion
16
More about the rock cycle
17
Rock Cycle Vocabulary
  • Uplift - rock moves up to Earths surface
  • Subsidence - rock moves down to lower levels of
    Earths surface.
  • Subduction - Rock subsides back down into the
    Earth.

18
Planet Earth
  • Earths Layers

19
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20
Crust
  • Earths thin outermost layer (4-7 miles deep).
  • Two parts
  • Continental Crust (land) - thick low density rock
    (granite).
  • Oceanic Crust (sea floor)- thin dense rock
    (basalt)

21
Mantle
  • Earths thickest layer made of dense iron-rich
    super heated soft rock.
  • 1800 miles thick

22
Core
  • Earths innermost layer made of hot, dense iron
    and nickel.
  • Outer core - Liquid
  • Inner core - Solid

23
What is plate tectonics?
24
Lithosphere
  • Earths cool, outermost layer that consists of
    the crust and the rigid, uppermost part of the
    mantle.
  • Divided into huge pieces called Tectonic
    Plates.
  • Tectonic plates move around on top of the
    asthenosphere (very hot, soft layer of the
    mantel).

25
Earths Tectonic Plates
26
Continental Drift Theory
  • 1915-Proposed by Alfred Wegener, German scientist
  • Theory that continents can drift apart from one
    another and have done so in the past.
  • Said that all of the continents were once in a
    super continent he called Pangaea (Greek for all
    land)
  • Used a variety of geological evidences to help
    support his hypothesis.
  • BBC Video Link
  • http//www.youtube.com/watch?vPvfokDNG5Xg

27
  • Wegeners Evidence of Continental Drift
  • Continents fit together
  • Similar fossils records
  • Similar types of rock and rock formations
  • Similar ancient climatic conditions
  • PROBLEM He couldnt explain how the plates moved
  • 1950-Wegeners hypothesis accepted as a theory
    (after his death in 1930) when sea floor
    spreading is proven.

28
Pangaea-the supercontinent
  • Pangea animation

29
Similar Fossil Records
30
Similar Rock Types and FormationsAppalachian
Mountain Range
31
Glaciations - Past evidence of glaciers
32
Sea Floor Spreading
  • Tectonic plates spread apart from each other at
    Mid Ocean Ridges and magma rises from inside the
    Earth creating new sea floor.
  • New sea floor pushes the existing sea floor out
    explaining why continents move.
  • Evidence that supports the theory of Continental
    Drift.

33
Sea Floor Spreading
34
  • Animations of plate boundaries and sea-floor
    spreading

35
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36
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37
Possible causes of Plate Tectonic Movement
  • Convection currents in the mantle where hot rock
    expands and rises and cooler rock sinks (Just
    like boiling water)
  • Ridge push at mid ocean ridges where magma comes
    up and pushes existing sea floor away.
  • Slab pull at subduction zones where oceanic crust
    sinks into the mantle and pulls the tectonic
    plate down.

38
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39
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40
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41
Tectonic Plate Boundaries
  • Convergent boundaries - When two tectonic plates
    collide - Forms mountains and trenches
  • Divergent boundaries - When two tectonic plates
    separate - Forms Mid Ocean Ridges
  • Transform boundaries - When two tectonic plates
    slide past each other horizontally - Forms Faults
    (ie.San Andres Fault)

42
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43
What happens at plate boundaries?
  • Divergent boundary-divorces/separate
  • Convergent boundary-converge/collide
  • Transform boundary-slide past each other

44
Divergent
  • Two plates pull away from each other
  • New oceanic crust forms at rift valleys
  • Magma oozes out and hardens to form new crust
    through seafloor spreading
  • Over time builds large mountain ranges on the
    ocean floor
  • Can form islands this way like Iceland
  • Examples Mid Atlantic Ridge, Atlantic Ocean is
    growing wider bc of this

45
Convergent
  • Two plates moving towards each other
  • Three main types
  • Continental/Continental-forms mountains like the
    Himalayan Mountains
  • Oceanic/Continental-trench forms, denser plate
    subducts (pulled down) Ex/Andes Mountains in Peru
  • Oceanic/Oceanic One plate is subducted along a
    trench causing a string of volcanic mountains to
    erupt. Ex/Aleutian Islands in Alaska

46
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47
Transform
  • Two plates slide past each other
  • Causes shearing (grinding of the two plates
    uneven surface against each other)
  • Results in earthquakes and fault lines (break in
    the crust)
  • Ex/San Andreas Fault in California

48
Volcanoes EarthquakesMost Occur at Tectonic
Plate Boundaries
49
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50
Plate tectonics and Earthquakes
51
Seismic Waves
Seismic Waves in 3-D
52
The Ring of Fire
53
Hot Spots
  • Found on the middle of tectonic plates
  • Magma inside the Earth rises and pushes through
    the crust and forms volcanoes.

54
Hawaii Islands
Oldest to youngest
55
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56
Super Volcanoes
  • Yellowstone National park, Wyoming
  • 3 overlapping calderas underground is believed to
    have formed from a hot spot creating
    Yellowstones Super Volcano
  • Last eruption was 640,000 years ago

57
Minerals
  • Naturally formed nonliving solid material that
    have crystal structures found in the Earth.
  • Minerals make up more than 90 of the the earths
    crust in rock and are used in important everyday
    items such as building materials, medicines and
    cosmetics.
  • Uses cement, building stones, and fireworks
    Fertilizer abrasives, aircraft parts, cosmetics,
    toothpaste, jewelry and paint, etc..

58
Color of minerals
  • Minerals come in all different colors

59
LusterMinerals can be shiny or dull
  • Metallic bright and reflective
  • Submetallic dull and reflective
  • Nonmetallic vitreous, silkey, resinous, waxy,
    pearly, or earthy

60
Minerals have Streak - Its color in powdered
form.
61
Minerals can break Cleavage vs. Fractures
62
Mineral Hardness
  • Its resistance to being scratched.
  • Measured by the Mohs Hardness Scale
  • 1 Softest - Talc
  • 10 Hardest Diamond
  • Test Minerals

63
Other Special Properties of Minerals
  • Density
  • Magnetism
  • Fluorescence
  • Taste
  • Chemical Reaction
  • Optical Properties
  • Radioactivity
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