ALEX Classroom Resource

  

Plate Movements: Divergent | NASA Online

  Classroom Resource Information  

Title:

 Plate Movements: Divergent | NASA Online

URL:

 https://www.knowitall.org/interactive/plate-movements-divergent-nasa-online

Content Source:

 Other
KnowItAll.org
Type: Informational Material

Overview:

This resource shows an example of a divergent boundary plate. At a divergent plate boundary, lithospheric plates move away from each other. As the two sides move away from each other, magma wells up from the Earth's interior. It then solidifies into the rock as it is cooled by the sea, creating a new ocean floor. The mid-Atlantic ridge, a topographically high area near the middle of the Atlantic Ocean, is an example of a divergent plate boundary.

Content Standard(s):
Science
SC2015 (2015)
Grade: 6
Earth and Space Science
9 ) Use models to explain how the flow of Earth's internal energy drives a cycling of matter between Earth's surface and deep interior causing plate movements (e.g., mid-ocean ridges, ocean trenches, volcanoes, earthquakes, mountains, rift valleys, volcanic islands).

NAEP Framework
NAEP Statement::
E12.12a: Movement of matter through Earth's systems is driven by Earth's internal and external sources of energy.

NAEP Statement::
E8.8: Earth is layered with a lithosphere; a hot, convecting mantle; and a dense, metallic core.

NAEP Statement::
E8.9a: Lithospheric plates on the scale of continents and oceans constantly move at rates of centimeters per year in response to movements in the mantle.

NAEP Statement::
E8.9b: Major geological events, such as earthquakes, volcanic eruptions, and mountain building, result from these plate motions.

Unpacked Content
Scientific And Engineering Practices:
Developing and Using Models
Crosscutting Concepts: Energy and Matter
Disciplinary Core Idea: Earth's Systems
Evidence Of Student Attainment:
Students:
  • Use models to explain how the flow of Earth's internal energy drives a cycling of matter between Earth's surface and deep interior causing plate movements.
Teacher Vocabulary:
  • Crust
  • Mantle
  • Outer core
  • Inner core
  • Lithosphere
  • Plates
  • Tectonic plates
  • Ocean plate
  • Continental plate
  • Asthenosphere
  • Convection
  • Convection current
  • Magma
  • Divergent plate boundary
  • Theory of Plate Tectonics
  • Convergent plate boundary
  • Transform plate boundary
  • Fault
  • Lava
  • Fissure
  • Geyser
  • Rift
  • Basalt
  • Granite
  • Density
  • Ocean trench
  • Subduction
  • Subduction zone
  • Earthquake
  • Mid-ocean ridge
  • Mountain
  • Rift valley
  • Volcano
  • Volcanic island
  • Undersea canyon
Knowledge:
Students know:
  • The layers of the Earth include, from outmost to innermost, the crust, mantle, outer core, and inner core.
  • The crust and upper mantle are broken into moving plates called the lithosphere. These plates are known as tectonic plates and fit around the globe like puzzle pieces.
  • The asthenosphere is located below the lithosphere. The asthenosphere is hotter and more fluid than the lithosphere. Convection occurs in the asthenosphere.
  • Convection is the transfer of heat by the actual movement of the heated material.
  • Through convection, movements deep within the Earth, which carry heat from the hot interior to the cooler surface, cause the plates to move very slowly on the surface.
  • The Theory of Plate Tectonics states that the outer rigid layer of the Earth is divided into a couple of dozen "plates" that move around across the Earth's surface relative to each other.
  • The areas where plates interact are called plate boundaries.
  • The three types of plate tectonic boundaries include divergent (dividing), convergent (colliding), and transform (grinding past each other).
  • Because ocean plates are denser than continental plates, when these two types of plates converge, the ocean plates are subducted beneath the continental plates. Subduction zones and trenches are convergent margins.
  • Subduction zones form when plates crash into each other, spreading ridges form when plates pull away from each other, and large faults form when plates slide past each other.
  • A divergent boundary occurs when two tectonic plates move away from each other. Along these boundaries, lava spews from long fissures and geysers spurt superheated water. Frequent earthquakes strike along the rift. Beneath the rift, magma—molten rock—rises from the mantle. It oozes up into the gap and hardens into solid rock, forming new crust on the torn edges of the plates. Magma from the mantle solidifies into basalt, a dark, dense rock that underlies the ocean floor. Thus at divergent boundaries, oceanic crust, made of basalt, is created.
  • When two plates come together, it is known as a convergent boundary. The impact of the two colliding plates buckles the edge of one or both plates up into a rugged mountain range called a mid-ocean ridge, and sometimes bends the other down into an ocean trench. Trenches are long, narrow, steep-sided depressions in the ocean floor. A chain of volcanoes often forms parallel to the boundary, to the mountain range, and to the trench. Powerful earthquakes shake a wide area on both sides of the boundary. If one of the colliding plates is topped with oceanic crust, it is forced down into the mantle where it begins to melt. Magma rises into and through the other plate, solidifying into new crust. Magma formed from melting plates solidifies into granite, a light colored, low-density rock that makes up the continents. Thus at convergent boundaries, continental crust, made of granite, is created, and oceanic crust is destroyed.
  • Two plates sliding past each other forms a transform plate boundary. Rocks that line the boundary are pulverized as the plates grind along, creating a rift valley or undersea canyon. As the plates alternately jam and jump against each other, earthquakes rattle through a wide boundary zone. In contrast to convergent and divergent boundaries, no magma is formed. Thus, crust is cracked and broken at transform margins, but is not created or destroyed.
Skills:
Students are able to:
  • Use a model of the flow of Earth's internal energy and the resulting plate movements and identify the relevant components.
  • Describe the relationships between components of the model including how the flow of Earth's internal energy drives a cycling of matter between Earth's surface and deep interior causing plate movements.
  • Articulate a statement that relates a given phenomenon to a scientific idea, including how the flow of Earth's internal energy drives a cycling of matter between Earth's surface and deep interior causing plate movements.
Understanding:
Students understand that:
  • The flow of Earth's internal energy drives a cycling of matter between Earth's surface and deep interior. This cycling of matter causes plate movements.
AMSTI Resources:
AMSTI Module:
Exploring Plate Tectonics
Alabama Alternate Achievement Standards
AAS Standard:
SCI.AAS.6.9- Recognize that volcanic action, earthquakes, and mountain building are caused by the flow of matter beneath Earth's surface.
Science
SC2015 (2015)
Grade: 9-12
Earth and Space Science
7 ) Analyze and interpret evidence regarding the theory of plate tectonics, including geologic activity along plate boundaries and magnetic patterns in undersea rocks, to explain the ages and movements of continental and oceanic crusts.

NAEP Framework
NAEP Statement::
E12.8: Mapping of the Mid-Atlantic Ridge, evidence of sea floor spreading, and subduction provided crucial evidence in support of the theory of plate tectonics. The theory currently explains plate motion as follows: the outward transfer of Earth's internal heat propels the plates comprising Earth's surface across the face of the globe. Plates are pushed apart where magma rises to form midocean ridges, and the edges of plates are pulled back down where Earth materials sink into the crust at deep trenches.

Unpacked Content
Scientific And Engineering Practices:
Analyzing and Interpreting Data
Crosscutting Concepts: Patterns
Disciplinary Core Idea: Earth's Systems
Evidence Of Student Attainment:
Students:
  • Analyze major geologic formations occurring at plate boundaries to determine the frequency of earthquakes to be expected.
  • Interpret topographical features presented on geologic maps to predict the associated type of plate boundary.
  • Draw diagrams that depict circulation within the mantle as it affects tectonic plate movement.
  • Analyze magnetic seafloor patterns to calculate oceanic crustal ages and directions of motion.
Teacher Vocabulary:
  • continental plate
  • Pangaea
  • continental drift
  • rift
  • continental crust
  • oceanic crust
  • mantle
  • hot spot
  • magnetometer
  • magnetic reversal
  • paleomagnetism
  • isochron
  • seafloor spreading
  • plate boundary
  • topography
  • divergent boundary
  • convergent boundary
  • transform boundary
  • subduction zone
  • ridge push
  • slab pull
Knowledge:
Students know:
  • Plate movements are responsible for most continental and ocean-floor features and for the distribution of most rocks and minerals within Earth's crust.
  • Spontaneous radioactive decays follow a characteristic exponential decay law.
  • Radiometric dating is used to determine the ages of rocks and other materials.
  • The youngest rocks are at the top, and the oldest are at the bottom in an undisturbed column of rock, .
  • Rock layers have sometimes been rearranged by tectonic forces and the rearrangements can be seen or inferred, such as inverted sequences of fossil types.
Skills:
Students are able to:
  • Organize data that represents patterns that can be attributed to plate tectonic activity and formation of new rocks.
  • Measure ratio of parent to daughter atoms produced during radioactive decay as a means for determining the ages of rocks.
  • Use analyzed data to determine age and location of continental rocks, ages and locations of rocks found on opposite sides of mid-ocean ridges, and the type and location of plate boundaries relative to the type, age, and location of crustal rocks.
Understanding:
Students understand that:
  • Plate tectonics is the unifying theory that explains the past and current movements of the rocks at Earth's surface and provides a framework for understanding its geologic history.
  • At the boundaries where plates are moving apart, such as mid-ocean ridges, material from the interior of the Earth must be emerging and forming new rocks with the youngest ages.
  • The regions furthest from the plate boundaries (continental centers) will have the oldest rocks because new crust is added to the edge of continents at places where plates are coming together, such as subduction zones.
  • The oldest crustal rocks are found on the continents because oceanic crust is constantly being destroyed at places where plates are coming together, such as subduction zones.
Tags: boundary, divergent, lithospheric, midAtlantic Ridge, plate
License Type: Attribution Non-Commercial No Derivatives
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Author: Stephanie Carver
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