What causes magnetic stripes on the seafloor such as those shown here?
At the mid-ocean ridge spreading axis, these flips in the direction of the Earth's magnetic field are recorded in the magnetization of the lava. This creates a symmetrical pattern of magnetic stripes of opposite polarity on either side of mid-ocean ridges.
What data was used to develop the continental drift hypothesis?
The evidence for continental drift included the fit of the continents; the distribution of ancient fossils, rocks, and mountain ranges; and the locations of ancient climatic zones.
How fast do plates move relative to one another quizlet?
How fast do tectonic plates move? They move at speeds ranging from 1 to 16 cm (0.4 to 6.3 in) per year.
How is magma created in a subduction zone quizlet?
Magma is produced in subduction zones by melting of the oceanic crust of the subducting plate.
How were the magnetic patterns on the seafloor discovered?
Data from magnetometers dragged behind ships looking for enemy submarines in WWII discovered amazing magnetic patterns on the seafloor. Rocks of normal and reversed polarity are found in stripes symmetrically about the mid-ocean ridge axis.
What does the magnetic stripes pattern represent?
This represents periodic reversals in the direction of the Earth's magnetic field.
What forms the basis of Wegener’s continental drift theory?
Wegener suggested that perhaps the rotation of the Earth caused the continents to shift towards and apart from each other. (It doesn't.) Today, we know that the continents rest on massive slabs of rock called tectonic plates. The plates are always moving and interacting in a process called plate tectonics.
What do you understand by the theory of continental drift discuss the prominent evidences in its support?
The theory deals with the distribution of the oceans and the continents. According to Wegener's Continental Drift theory, all the continents were one single continental mass (called a Super Continent) – Pangaea and a Mega Ocean surrounded this supercontinent. The mega ocean is known by the name Panthalassa.
Which of the following plate boundaries does new oceanic lithosphere forms?
A divergent boundary occurs when two tectonic plates move away from each other. Along these boundaries, earthquakes are common and magma (molten rock) rises from the Earth's mantle to the surface, solidifying to create new oceanic crust.
What is the boundary form where two plates bump into each other?
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. Deep trenches are features often formed where tectonic plates are being subducted and earthquakes are common.
How does magma form in the line of arc volcanoes over an active subduction zone quizlet?
Water from subducting oceanic lithosphere seeps into the overlying wedge of hot mantle – results in melting of mantle rocks to mafic magma. Magma rises to crust, forming a volcanic arc (chain of active volcanoes).
How is magma generated along convergent plate boundaries quizlet?
How is magma generated along convergent plate boundaries? –Friction from the subducting slab raises the temperature of the rock under which it subducts, melting this rock into magma.
What does this pattern suggest about how the seafloor forms?
Distance from Oceanic Ridge (km) VGP Latitude (deg.) The stripes are symmetric across the Oceanic Ridge. They create a mirror image. It suggests that new seafloor is formed in the middle (at the Ridge) and some of the new seafloor moves to each side of the Ridge forming a symmetric pattern.
How does the observed pattern of magnetic reversals support the theory of sea floor spreading?
When the Earth's magnetic field reverses, a new stripe, with the new polarity, begins. Such magnetic patterns led to recognition of the occurrence of sea-floor spreading, and they remain some of the strongest evidence for the theory of plate tectonics.
How do magnetic anomaly patterns on the ocean floor best serve as evidence for seafloor spreading?
magnetic polarity reversals. How do magnetic anomaly patterns on the ocean floor best serve as evidence for seafloor spreading? The symmetry on either side of mid-ocean ridges shows that new crust is created and then split apart.
What is the orientation of the magnetic stripes of iron contained in rocks that support the idea of seafloor spreading?
When geologists studied the polarity of ancient rocks, they were stunned to discover that in many of them, iron minerals were aligned toward the south magnetic pole, not the north. Scientists have concluded that the Earth's magnetic field has reversed itself again and again throughout the ages.
How did continents form?
In 1912, German scientist Alfred Wegener proposed a theory he called continental drift. According to Wegener's theory, Earth's continents once formed a single, giant landmass, which he called Pangaea. Over millions of years, Pangaea slowly broke apart, eventually forming the continents as they are today.
How were the fossil symbols and mountain belts helpful in deciding where to move the continents?
How were the fossil symbols and mountain belts helpful in deciding where to move the continents? They made it a lot easier to see where to put the pieces. Otherwise, it was really hard to fit them all together. Why don't the present shapes of the continents fit perfectly into a supercontinent?
What is the conclusion of continental drift?
Wegener took the areas that had been covered by ice sheets and fitted them together around the south pole. HIS CONCLUSION – the continents were once part of a single larger continent that then split apart, drifting to their present positions over the last 300 million years.
Which plate boundary and movement commonly create non volcanic mountains explain how non volcanic mountains are created by plate tectonics?
Answer and Explanation: The convergent boundary is one where the impact of the two plates towards one another results in the formation of non-volcanic mountains.
What type of convergent plate boundary triggers the formation of active volcanoes as magma rises beneath the surface?
Subduction zones Subduction zones have a lot of intense earthquakes and volcanic eruptions. The subducting plate causes melting in the mantle above the plate. The magma rises and erupts, creating volcanoes.
How will you describe the movement of the plate or crust in convergent boundaries give examples of landform of this type?
Typically, a convergent plate boundary—such as the one between the Indian Plate and the Eurasian Plate—forms towering mountain ranges, like the Himalaya, as Earth's crust is crumpled and pushed upward. In some cases, however, a convergent plate boundary can result in one tectonic plate diving underneath another.
What happens to the crust behind a Migrating island arc as it moves along with a subducting slab?
What happens to the crust behind a migrating island arc as it moves along with a subducting slab? A back-arc basin forms. A spreading center develops. The crust thins and a rift forms.
How does felsic magma form in the line of arc volcanoes like the Cascades?
How does felsic magma form in the line of arc volcanoes like the Cascades? Mafic magma from the subducted plate rises to melt the continental crust to form the felsic magma.
How is magma generated at divergent boundaries Group answer choices?
At divergent boundaries magma forms because of decompression melting. Decompression melting also takes place within a mantle plume.
How is magma generated along a convergent plate boundaries?
Transfer of heat often happens at convergent boundaries, where tectonic plates are crashing together. As the denser tectonic plate subducts, or sinks below, or the less-dense tectonic plate, hot rock from below can intrude into the cooler plate above. This process transfers heat and creates magma.
What is the major evidence that sea floor spreading creates new lithosphere explain your answer?
The record of magnetic reversals is carried away from each side of the spreading center of a mid-ocean ridge showing that the molten rock is creating new lithosphere.
What does this pattern suggests about how the seafloor forms?
Distance from Oceanic Ridge (km) VGP Latitude (deg.) The stripes are symmetric across the Oceanic Ridge. They create a mirror image. It suggests that new seafloor is formed in the middle (at the Ridge) and some of the new seafloor moves to each side of the Ridge forming a symmetric pattern.
How would the history of magnetic reversals show itself on the ocean floor?
The seafloor is spread by a mid-ocean ridge. Rocks farther away are older, and rocks closer to the ridge are newer. As the magma from the ridge cools, some of it's molecules orient themselves with the magnetic field. When the field reverses, the polarity of the rocks also reverses.
How does the observed pattern of magnetic reversals support the theory of sea-floor spreading?
When the Earth's magnetic field reverses, a new stripe, with the new polarity, begins. Such magnetic patterns led to recognition of the occurrence of sea-floor spreading, and they remain some of the strongest evidence for the theory of plate tectonics.