solid earth final review. layers crust, mantle, outer core, inner core
TRANSCRIPT
SOLID EARTH
FINAL REVIEW
Layers crust, mantle, outer core, inner core
Inner core- solid iron & nickelOuter core- liquid iron & nickel, where magnetic field is generated
Mantle makes up most of Earth’s mass
Lithosphere- is the solid crust & upper mantle
(the tectonic plates)
Asthenosphere- soft layer of upper mantle (convection currents)
Pressure and temperature increase with depth
Magma is formed when rock melts
Primary (p waves ) are compression waves
• Secondary waves (s waves) are shear waves
P waves can travel through BOTH solids and liquid
• S waves can only travel through solids
Seismic waves arrive in this order- P, S, then surface
Indirect evidence of the interior is obtained by studying seismic waves
Ocean crust gets denser as it gets cooler
MORE DENSE
LESS DENSE
Oceanic crust is denser and younger than continental
• Continental crust is older than oceanic
Oceanic crust is mostly basaltContinental crust is mostly granite
• Oceanic Continental
Sediments get thicker and older away from the mid-ocean ridge
Convection currents in the mantle move tectonic plates
Seismographs record ground movements
Earthquakes can cause; building collapse, soil liquefaction, and a tsunami
E3.4B
• Richter scale measures ground movement• Moment magnitude scale measures energy
released• Mercalli scale measures earthquake damage
Earthquakes with a shallow focus are more likely to cause severe damage
A bulge in the surface of a volcano is a warning sign
• A "bulge" developed on the north side of Mount St. Helens as magma pushed up within the peak. Angle and slope-distance measurements to the bulge indicated it was growing at a rate of up to five feet (1.5 meters) per day. By May 17, part of the volcano's north side had been pushed upwards and outwards over 450 feet (135 meters). The view is from the northeast.
Movements along a fault are measured with; tilt meters, laser ranging devices, and
GPS satellites
E3.4C
• A Tsunami is a giant wave caused by an underwater earthquake
Aftershocks can cause more damage and injuries so people should NOT go back inside
Actual ground movement is least likely to cause deaths during earthquakes
Deaths occur from collapsing dams flooding, falling debris, and fires from broken electric and gas lines
E3.4C• Types of rock and soil under buildings affect
how it responds to an earthquake
Seismic gaps, foreshocks and changes in rock help forecast earthquakes
Japan’s March 11, 2011 Earthquake
Earthquake risk is high on the Pacific coast because the Pacific and North American plates meet at the San Andreas Fault
Most EQ and Volcanoes occur at plate boundaries and where stress on the rock is greatest
Transform boundary forms when plates slip past each other
A fault is a break in the Earth’s crust
Heat transfer by direct contact is conduction, by flowing in a fluid is convection and through open space is radiation.
Wegener’s hypothesis stated the continents were once joined as Pangaea and then broke apart.
Wegener’s hypothesis stated the continents were once joined as Pangaea and then broke apart.
Convection currents occur because heated material becomes less dense and rises
The density of each plate determines what occurs when plates collide
Plate tectonic theory explains why and how continents move
A rift valley forms when two continental plates diverge
Sea-floor spreading causes new ocean floor to constantly be produced
When oceanic and continental plates collide the oceanic plate subducts under the
continental
An underwater mountain chain formed by sea-floor spreading is called a mid-ocean ridge
Along mid-ocean ridges molten material rises from the mantle
Uplifting brings rocks to Earth’s surface where they then can erode
The Himalayas formed by the process of convergence.
Divergence forms rift valleys and the mid-ocean ridges
Deep-ocean trenches form in a subduction zone
• In plate movement speed = distance / time so a plate that moved 550 cm in 50 years moved at a rate of 550/50= 11 cm/year
Carbon¹⁴ dating works because of carbon in living things, it doesn’t work on the moon
The half-life of a radioactive element is the time it takes for ½ of the atoms to decay
Radioactive decay is when atoms of an unstable element break down to form another element
• Fossils provide evidence for; changes in the Earth’s surface, how environments have changed over time, how groups of organisms have changed over time.
Fossils are most common in sedimentary rocks
Index fossils were; common while alive, existed for a short distinct time, geographically widespread, and easily recognizable
Index fossils tell the relative age of rocks. Rocks with identical index fossils are about the same age
Index fossils tell the
relative age of rocks.
Rocks with identical
index fossils are about the
same age
USGS
Earth is about 4.6 billion years old
Most of the atmosphere now is Nitrogen
The atmosphere formed during the precambrian time
The impact hypothesis states an asteroid or meteorite from space caused the extinction of dinosaurs.
The gradual development
of new organisms
from preexisting
ones is called evolution
Geologic time scale is a record of life forms and geologic events in Earth’s history
The longest geologic time is the precambrian
Fossils are rare in precambrian rocks because most precambrian organisms had soft body parts that did not form fossils
E5.3C cont.
• Blue green bacteria used photosynthesis to make food and produced more oxygen in the atmosphere. Photosynthesis produces oxygen
During the rise of life a great number of different organisms evolved
Ozone layer formation allowed plants and animals to move out of the water onto
land during the Paleozoic Era
• The Permian mass extinction probably occurred because organisms could not live in the new climate created by Pangaea
Earth’s ‘second atmosphere’ was made of mostly carbon dioxide, nitrogen and water vapor
The Cenozoic mass extinction of large mammals probably occurred because of
the ice ages
• Volcanic out gassing helped form the Earth’s atmosphere
Done E5.3C
The geologic
time scale is divided
into eras and
periods
Some Sedimentary rocks form from fragments of other rocks
• Steps to form sedimentary rocks from igneous rock are erosion, deposition, compaction and cementation- erosion removes and transports rock materials
Lynn S. Fichter © 2000
Rocks change to metamorphic rock by heat and pressure
Rock cycle is the process rocks follow to change to other rocks; igneous, sedimentary, &
metamorphic
Large crystals form in granite when it cools slowly
• Plate collisions affect the rock cycle when one plate is forced down to the heat of the mantle and produces metamorphic rock
During an Earthquake stand in a doorway or crouch under a desk
Fossils of tropical plants are found in Antarctica giving evidence plates moved
Sonar is used to map the ocean floor
The Pacific Ring of Fire is a zone of volcanoes and earthquakes
USGS
The Pacific Ring of Fire is a zone of volcanoes and earthquakes
• The mantle is heated by earth’s core energy and radioactivity
Past earthquakes are studied to predict where future earthquakes may occur
The composition of the interior affects the speed and direction of seismic waves
Subduction is one plate going under another
Volcanic mountains form at a convergent boundary of two plates
Following are the slides #73-end combined
• The Permian mass extinction probably occurred because organisms could not live in the new climate created by Pangaea
• Earth’s ‘second atmosphere’ was made of mostly carbon dioxide, nitrogen and water vapor
• • The Cenozoic mass extinction of large
mammals probably occurred because of the ice ages
• Volcanic out gassing helped form the Earth’s atmosphere
• The geologic time scale is divided into eras and periods
• Some Sedimentary rocks form from fragments of other rocks
• Steps to form sedimentary rocks from igneous rock are erosion, deposition, compaction and cementation- erosion removes and transports rock materials
• Rocks change to metamorphic rock by heat and pressure
• Rock cycle is the process rocks follow to change to other rocks; igneous, sedimentary, & metamorphic
• latals form in granite when it cools slowly form in granite when it cools slowly
• Plate collisions affect the rock cycle when one plate is forced down to the heat of the mantle and produces metamorphic rock
• During an Earthquake stand in a doorway or crouch under a deskFossils of tropical plants are found in Antarctica giving evidence plates moved
• The mantle is heated by earth’s core energy and radioactivity