Which is the first step in the seafloor spreading process?
A crack forms in oceanic crust. Molten rock rises up through oceanic crust. Molten rock solidifies at the center of the ridge.
How do plate movements affect humans?
Plate tectonics affects humans in several important ways. What would Earth be like without plate tectonics? We’d have many fewer earthquakes and much less volcanism, fewer mountains, and probably no deep-sea trenches. In other words, the Earth would be a much different place.
What are tectonic plates easy definition?
A tectonic plate (also called lithospheric plate) is a massive, irregularly shaped slab of solid rock, generally composed of both continental and oceanic lithosphere. Continental crust is composed of granitic rocks which are made up of relatively lightweight minerals such as quartz and feldspar.
What represent the plates?
Answer. Explanation: The boundaries between plates are indicated with three symbols. The lines with gray shading indicate divergent plate boundaries, the “triangle” symbol represents convergent plate boundaries and the single line with or without the “T” indicates transform plate boundaries.
What are the three types of seafloor spreading?
There are three types of plate-plate interactions based upon relative motion: convergent, where plates collide, divergent, where plates separate, and transform motion, where plates simply slide past each other.
What happens when a tectonic plate gets subducted?
Where two tectonic plates meet at a subduction zone, one bends and slides underneath the other, curving down into the mantle. (The mantle is the hotter layer under the crust.) At a subduction zone, the oceanic crust usually sinks into the mantle beneath lighter continental crust.
What happens when tectonic plates meet?
If two tectonic plates collide, they form a convergent plate boundary. Usually, one of the converging plates will move beneath the other, a process known as subduction. The new magma (molten rock) rises and may erupt violently to form volcanoes, often building arcs of islands along the convergent boundary.
What is the border between two tectonic plates called?
Is fossil material evidence of seafloor spreading?
Harry Hess’s hypothesis about seafloor spreading had collected several pieces of evidence to support the theory. This evidence was from the investigations of the molten material, seafloor drilling, radiometric age dating and fossil ages, and the magnetic stripes.
What force causes the movement of Earth’s plates?
Where are tectonic plates?
The lithosphere, which is the rigid outermost shell of a planet (the crust and upper mantle), is broken into tectonic plates. The Earth’s lithosphere is composed of seven or eight major plates (depending on how they are defined) and many minor plates.
What is seafloor spreading?
Seafloor spreading is a geologic process in which tectonic plates—large slabs of Earth’s lithosphere—split apart from each other. Seafloor spreading and other tectonic activity processes are the result of mantle convection.
What are the evidence of seafloor spreading?
Abundant evidence supports the major contentions of the seafloor-spreading theory. First, 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.
What are the 12 tectonic plates?
- African plate.
- Antarctic plate.
- Indo-Australian plate.
- North American plate.
- Pacific plate.
- South American plate.
- Eurasian plate.
What are the 4 steps of seafloor spreading?
What are the 4 steps of seafloor spreading?
- Magma comes out of the rift valley.
- Magma cools to rock and hardens.
- Rock is pushed away as new rock is formed at MOR.
- Oceanic crust and continental crust meet at the trench.
- Oceanic crust bends down under the continental crust.
- Gravity pulls rock towards mantle.
- Rock melts to mantle.
What will happen if divergence continues?
Divergent Plate Boundaries Plates move apart at mid-ocean ridges where new seafloor forms. Between the two plates is a rift valley. If divergence continues, a sea can form like the Red Sea and finally an ocean like the Atlantic Ocean.
What happens when two tectonic plates diverge?
The plates diverge and this causes the construction of new rock. It happens when two tectonic plates pull apart and rock from the mantle rises up through the opening to form new surface rock when it cools. It happens at the start of a new ocean and continues at the mid-ocean ridge while the ocean is opening.
Which way are the tectonic plates moving?
The Pacific Plate is moving to the northwest at a speed of between 7 and 11 centimeters (cm) or ~3-4 inches a year. The North American plate is moving to the west-southwest at about 2.3 cm (~1 inch) per year driven by the spreading center that created the Atlantic Ocean, the Mid Atlantic Ridge.
What is the importance of seafloor spreading?
Today it refers to the processes creating new oceanic lithosphere where plates move apart. Seafloor spreading replaces the lithosphere destroyed by subduction, and exerts important influences on Earth’s chemical and biological evolution.
What are the two main factors of tectonic plates movement?
Heat and gravity are fundamental to the process The energy source for plate tectonics is Earth’s internal heat while the forces moving the plates are the “ridge push” and “slab pull” gravity forces.
Why do plates get subducted?
Subduction is a geological process that takes place at convergent boundaries of tectonic plates where one plate moves under another and is forced to sink due to high gravitational potential energy into the mantle. Regions where this process occurs are known as subduction zones.
What are the features of seafloor?
Features of the ocean include the continental shelf, slope, and rise. The ocean floor is called the abyssal plain. Below the ocean floor, there are a few small deeper areas called ocean trenches. Features rising up from the ocean floor include seamounts, volcanic islands and the mid-oceanic ridges and rises.