Earth

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Earths internal processes???????????????????
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• Convection current theory
• ??????????????????????

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??? (Plate) ??????????????????????????????
???????????? ??????????????????????
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Continental Drift Theory ???????????????
?.?.1915 ???????????????????????????? Alfred
Wegener ??????? The origin of Continental and
Oceans

• ??????????? ???????? 250 ?????????? ???????? ?
  ????????????????????????????????? ???????
  (Pangea) ????????????????????????????????
• ????????????????????????????????????
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Sea Floor Spreading Theory ???????????????????????
????????
?.?.1960s American geologist Harry H. Hess

• Theory of lithospheric evolution that holds that
  the ocean floors are spreading outward from vast
  underwater ridges
• ??????????????????????????????????????????????????
  ?????
• - Discovery mid-ocean ridge ??????????????????????
  ?????????
• samples of the deep ocean floor show that
  basaltic oceanic crust and overlying sediment
  become progressively younger as the mid-ocean
  ridge is approached, and the sediment cover is
  thinner near the ridge ???????????????????????????
  ??????????????????????????????????????????????????
  ???????????
• rock making up the ocean floor is considerably
  younger than the continents ????????????
  ?????????????? ????????

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??????????????????????????????????(Plate
Tectonic Theory)
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????????????????????????????? Plate Tectonics

• Divergent boundaries ???????????????????
• Convergent boundaries ???????????????????
• Oceanic-continental convergence
• Oceanic-oceanic convergence
• Continental-continental convergence
• Transform boundaries ???????????????????????
  ??????????? ???????? ?????????????????

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LITHOSPHERE AND ASTHENOSPHERE???????
?????????????

• The lithosphere ??????? ??????????
• the upper rigid mantle ????????????????????
• the overlying oceanic or continental crust
  ??????????????????????????????????????????????????
  ??
• The asthenosphere is capable of flow.
  ??????????????????????????????????????????????????
  ??????????????????????????????????????????????????
  

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DIVERGENCE ??????????????????????

• Heat flow causes the lithosphere to break apart
  (divergence) and form a rift valley. These rift
  valleys form the boundaries between plates and
  new rock is formed as the magma cools. This is
  referred to as sea-floor spreading.
  ??????????????????????????????????????????????????
  ??????
• Older rock is pushed aside where new rock is
  forming. As distance from mid-ocean ridges
  increases, age of rock also increases. Most
  divergent boundaries have mid-ocean ridges with
  deep rift valleys along their entire length.
  ??????????????????????????????????????????????????
  ?????????????????????????

OLDER ROCK
OLDER ROCK
HEAT FLOW
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DIVERGENCE WITH TRANSFORM FAULTS?????????????????
?????????????????????????????????

• Rift valleys are broken into segments by
  transform faults. Movements along these
  fractures are a source of earthquakes that occur
  along the ridge.
• ?????????????????????????????????? ??????????????
  transform faults

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mid-ocean ridges ????????????????????
?????????????
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TRANSFORM BOUNDARY?????????????????????

• At the boundaries of some areas, the lithospheric
  plates are sliding past each other. Frequent
  earthquakes occur along these transform
  boundaries as huge masses of rock move.

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TRANSFORM BOUNDARY?????????????????????
??????????????????????????????????????????
San Andreas Fault
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TRANSFORM BOUNDARY?????????????????????
??????????????????????????????????????????

• The San Andreas Fault, located in western
  California
• ????????????? ???????????? ???????? San Andreas
  Fault
• the source of frequent earthquakes.
  ??????????????????????????
• the Pacific Plate and the North American Plates
  are sliding past each other. ????????????????????
  ?????????????????????????????
• average rate about 5 cm per year.
  ??????????????? 5 ?????????
• Some areas have not moved for centuries.
  Pressure has been building and is thought to be
  the most likely places for future earthquakes.
• ?????????????????????????????????????????
  ??????????????????????????????????????????????????
  ??????

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CONVERGENCE ocean-continental plate
boundary?????????????????????????????????????????
????

• Continental crust is made of granite, which is
  less dense than ocean crust, which is made of
  basalt.
• ????????????????????? ????????????????????????????
  ????? ??????????????????
• The more dense ocean crust subducts (goes under)
  continental crust, forming a deep trench on the
  ocean floor.
• ??????????????????????????????????????????????????
  ????????????????? trench
• High temperatures and pressures in the
  asthenosphere cause the subducting plate to melt.
• ??????????????????????????????????????????????????
  ???????????????

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CONVERGENCE ocean-continental plate
boundary?????????????????????????????????????????
????

• Magma then rises to the surface and escapes in
  volcanic eruptions, forming major mountain ranges
  on the continent.
• ??????????????????????????????????????????????????
  ????????????????? ????????????????????????
• Eruptions can be very violent and earthquakes at
  subduction boundaries occur much deeper in the
  lithosphere than at other plate boundaries.
• ??????????????????????????????????????????????????
  ??????????????????????????????????????????????????
  ???????????

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CONVERGENCE ocean-continental plate
boundary?????????????????????????????????????????
????
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CONVERGENCE oceanic-oceanic plate boundary
?????????????????????????????????????????????????

• Where two ocean plates converge, the older, more
  dense ocean crustal plate subducts under the
  younger, less dense.
• ??????????????????????????????????????????????????
  ????????????????????????????????????????????????
• the older crust is farther from the mid-ocean
  ridge where it was originally formed as new
  seafloor.
• ??????????????????????????????????????????????????
  ?????????????
• Island arcs are formed near ocean trenches as
  subducting plates are melted and rise to the
  surface as volcanic eruptions.
• ?????????????? Island arcs ???????????????????????
  ??????????????????????????????????????????????????
  ????????????????????
• Island arcs are found along the Aleutian Trench
  and Tonga Trench in the Pacific Ocean

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CONVERGENCE oceanic-oceanic plate boundary
?????????????????????????????????????????????????
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CONVERGENCE continental-continental plate
boundary?????????????????????????????????????????

• If converging plates are both carrying
  continents, the continents may be welded into a
  single larger continent. This converging
  boundary is known as a collision boundary. The
  collision causes the lithosphere to be pushed up
  into a mountain range. ???????????????????????????
  ???????????????????????????????????????????????

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CONVERGENCE continental-continental plate
boundary?????????????????????????????????????????
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CONVERGENCE India colliding with
Asia??????????????????????????

• The Himalayan Mountains are an example of a
  collision boundary that is still forming today.
• ????????????????????????
• India is pushing northward into China at a rate
  of about 5 cm each year.
• ??????????????????????????????????????????????????
  ??????????????? 5 ?????????
• India is now welded to the Eurasian continent
  with the worlds highest mountains and frequent
  earthquakes.
• ??????????????????????????????????????????????????
  ?????????????????????

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CONVERGENCE

• This map shows the Australian-Indian plate
  colliding with the Eurasian plate. Find India
  and the Himalayan Mountains.

HIMALAYAN MOUNTAINS
INDIA
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Physical world maplocations of mountain
ranges???????????

• Mountain ranges are formed at active plate
  boundaries where tectonic plates are converging.

Cascades
Himalayas
Andes
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WORLD MAP TECTONIC PLATE BOUNDARIES
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Earthquakes ??????????
?????????? ???????????????????????????????????????
??????????????????? ??????????????????????????????
??????????????????????????????????????????????????
???????????????????????????????????????????
????????????????????????????????? (Richter)
M log A- log Ao ????? M ?????????????????? A
????????????????????????? Ao ?????????????????????
??????????? ???????????? 0.001 ??.
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Deeper focus earthquakes occur in subduction
zones along convergent plate boundaries. Shallow
focus earthquakes occur along mid-ocean ridges
and transform boundaries.
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EARTHQUAKE FOCI DEPTH Japan trench region

• Japan is an island arc created from the
  subduction of the Pacific Plate. Earthquakes in
  western Japan are deeper than earthquakes in
  eastern Japan.

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Many earthquakes and volcanic eruptions surround
the Pacific Ocean. This is known as the Ring of
Fire.
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Tsunami ?????????????????
A
B
D
C
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Tsunami
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Volcanism
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(????????????????????????????????????????????)
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??
active volcanoes ????????????? ???
???????????????????????? ???????????? ? domant
?????????????? ??????????????????????????????????
??? extinct ?????????????? ???
??????????????????????????????????????????????
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Volcanic activity occurring at subduction
boundaries usually results in more violent
eruptions.
Figure 1 Mount St. Helens
Figure 2 Mt. Uluigalau Volcano, Fiji
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TECTONIC HOT SPOTS

• Not all volcanism occurs at plate boundaries.
  Hot spots are usually located in the middle of
  lithospheric plates. The hot spot seems to
  remain in the same location while the plate moves
  over it. This results in a chain of extinct
  volcanic islands like the Hawaiin Islands.

Direction of Plate Movement
North
KAUAI
OAHU
MOLOKAI
Active Volcano is over the Hot Spot
MAUI
HAWAII
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Principal Types of Volcanoes

• ??????????????? stratovolcanoes ????Composite
  volcano
• Fujiyama

• steep-sided
• symmetrical cones

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Cinder cone ???????????????
Photograph by J.P. Lockwood on 1 December 1975 This cinder cone (Puu ka Pele) was erupted low on the southeast flank of Mauna Kea Volcano. The cone is 95 m in height, and the diameter of the crater at the top is 400 m. Hualalai Volcano in background. A cinder cone is a steep, conical hill of volcanic fragments that accumulate around and downwind from a vent. The rock fragments, often called cinders or scoria, are glassy and contain numerous gas bubbles "frozen" into place as magma exploded into the air and then cooled quickly. Cinder cones range in size from tens to hundreds of meters tall.
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Shield volcano ?????????????
Photograph by D. Little Mauna Loa Volcano Hawai Shield volcano Volcanoes with broad, gentle slopes and built by the eruption of fluid basalt lava are called shield volcanoes. Basalt lava tends to build enormous, low-angle cones because it flows across the ground easily and can form lava tubes that enable lava to flow tens of kilometers from an erupting vent with very little cooling. The largest volcanoes on Earth are shield volcanoes. The name comes from a perceived resemblance to the shape of a warrior's shield.
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Caldera
Photograph by M. Williams, National Park Service, 1977 Aniakchak Caldera formed during an enormous explosive eruption that expelled more than 50 km3 of magma about 3,450 years ago. The caldera is 10 km in diameter and 500-1,000 m deep. Subsequent eruptions formed domes, cinder cones, and explosion pits on the caldera floor. CalderaA caldera is a large, usually circular depression at the summit of a volcano formed when magma is withdrawn or erupted from a shallow underground magma reservoir. The removal of large volumes of magma may result in loss of structural support for the overlying rock, thereby leading to collapse of the ground and formation of a large depression. Calderas are different from craters, which are smaller, circular depressions created primarily by explosive excavation of rock during eruptions.
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?????????????????Caldera
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PLATE TECTONICS AND THE ROCK CYCLE

• New rocks are continually being created due to
  tectonic forces.
• Igneous rocks form from the solidification of
  magma and volcanic lava.
• Metamorphic rocks are changed by the heat and
  pressure caused by converging of tectonic
  plates.
• Sedimentary rocks are created when other rocks
  are weathered and eroded, deposited as sediments,
  and then compacted and cemented.Find the
  location of each of these processes in the
  diagram below.

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Igneous Rocks ????????
Volcanic rocks (also called extrusive igneous
rocks) ?????????? ??????????????
??????????????????????????????????????????????????
???????????????????????? (Lava)
??????????????????????????????????? ????
?????????? (Basalt) ???????????? (Andesite)
??????????? (Rhyolite)
Plutonic rocks (also called intrusive igneous
rocks) ??????????????? ???? ?????????????
??????????????????????????? ? ????????????????????
?? ????????????????? (gt1 ?????????) ?????????????
(Granite) ??????????? (Diorite) ?????????
(Gabbro)
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Volcanic Rocks
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Sedimentary rocks ????????
- ????????????????? (Clastic Sedimentary Rock)
??????????????????????????????? ??????? ????
???????????? ?????????????????????????? ????
??????? (Sandstone) ????????? (Shale) ?????????
(Conglomerate) ???????

• ?????????????? (Nonclastic Sedimentary Rock)
  ?????????????????????????????????
  ?????????????????? ???????????????????????????????
  ???????????????? ???? ?????? (Limestone)
  ????????? (Chert)
• ???????? (Rock Salte) ??????? (Coal) ???????

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Metamorphic Rock ??????
- ????????????????????? (Regional metamorphism)
??????????????????????????????????????????????????
???????????????????????????? ?????????????????????
????? ??????????????? (Foliation)
??????????????????????????????????????????????????
??????????? ???? ??????? (Gneiss) ????????
(Schist) ?????????? (Slate) ???????
- ???????????????? (Contact metamorphism)
??????????????????????????????????????????????????
????????????????????????????????????????????????
???????????????????????????? ?????????????????????
??????????????????????????????????????????????????
??? ?????????????????????????????????????????????
??????????????? (Nonfoliation) ???? ???????
(Marble) ??????????? (Quartzite)
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??????????????
??????? (Slate)
??????? (Gneiss)
??????????? (Quartzite)
??????? (Marble
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