solid earth final review. layers crust, mantle, outer core, inner core

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