He proposed that volcanic island chains, like the Hawaiian Islands, are
created by fixed “hot spots” in the mantle
. At those places, magma forces its way upward through the moving plate of the sea floor. As the plate moves over the hot spot, one volcanic island after another is formed.
How does plate tectonics cause volcanic islands to form in chains?
As a crustal tectonic plates move over hot spots mantle material upwells and erupts on the surface of the plate to
form a volcano, seamount or volcanic island. The islands and seamounts of the Hawaiian Archipelago were created by a hot spot under the Pacific Plate that has been active for the past 41 million years.
How can the plate tectonic theory explain the formation of volcanoes?
On land, volcanoes form
when one tectonic plate moves under another
. Usually a thin, heavy oceanic plate subducts, or moves under, a thicker continental plate. … When enough magma builds up in the magma chamber, it forces its way up to the surface and erupts, often causing volcanic eruptions.
How do plate tectonics explain the effects of volcanic activities such as the formation of island chains and island arcs?
It is circular convection cycles in the magma of the asthenosphere that cause the tectonic plates to move. When one tectonic plate
meets another and sinks underneath it
, we call the phenomenon subduction. There are many subduction zones in the Ring of Fire, and it is in these zones that island arcs can form.
What does the plate tectonic theory explain?
The theory of plate tectonics states
that the Earth’s solid outer crust, the lithosphere, is separated into plates that move over the asthenosphere, the molten upper portion of the mantle
. Oceanic and continental plates come together, spread apart, and interact at boundaries all over the planet.
Why do tectonic plates move?
The heat from radioactive processes within the planet’s interior causes the plates
to move, sometimes toward and sometimes away from each other. This movement is called plate motion, or tectonic shift.
What are the two types of crust?
Earth’s crust is divided into two types:
oceanic crust and continental crust
. The transition zone between these two types of crust is sometimes called the Conrad discontinuity. Silicates (mostly compounds made of silicon and oxygen) are the most abundant rocks and minerals in both oceanic and continental crust.
How volcanic arc is formed?
Beneath the ocean, massive tectonic plates converge and grind against one another, which drives one below the other.
What is the relationship between the crust and lithosphere quizlet?
What is the relationship between the crust and the lithosphere?
All of the crust is contained within a larger layer called the lithosphere
. What is the relationship between the mantle and the lithosphere? Some of the mantle is contained within a smaller layer called the lithosphere.
How a volcanic island is formed?
As volcanoes erupt, they build up layers of lava that may eventually break the water’s surface.
When the tops of the volcanoes appear above the water, an island
is formed. While the volcano is still beneath the ocean surface, it is called a seamount. Oceanic islands can form from different types of volcanoes.
What are the 3 theories of plate tectonics?
The three types of plate boundaries are
divergent, convergent, and transform
. They are described in the following three concepts. Most geological activity takes place at plate boundaries.
What are the 4 types of plate tectonics?
- Divergent: extensional; the plates move apart. Spreading ridges, basin-range.
- Convergent: compressional; plates move toward each other. Includes: Subduction zones and mountain building.
- Transform: shearing; plates slide past each other. Strike-slip motion.
What is the theory of plate tectonics Class 9?
Plate tectonics is the
theory that states that Earth’s outer shell is divided into several plates that glide over the mantle
. The plates act like a hard and rigid shell compared to Earth’s mantle. This strong outer layer is called the lithosphere. Plate tectonics is the modern version of continental drift.
How fast do tectonic plates move?
They can move at
rates of up to four inches (10 centimeters) per year
, but most move much slower than that. Different parts of a plate move at different speeds. The plates move in different directions, colliding, moving away from, and sliding past one another. Most plates are made of both oceanic and continental crust.
What happens when tectonic plates move?
When the plates move
they collide or spread apart allowing the very hot molten material called lava to escape from the mantle
. When collisions occur they produce mountains, deep underwater valleys called trenches, and volcanoes. … The Earth is producing “new” crust where two plates are diverging or spreading apart.
What are three causes of plate movement?
Mantle dynamics, gravity, and Earth’s rotation taken
altogether causes the plate movements. However, convectional currents are the general thought for the motion.
