15 Questions
What is the composition of the Earth's core?
Fe and Ni
What is the lithosphere?
A solid, rigid, and elastic layer
What is the main evidence for the Continental Drift Theory?
Continental Jigsaw Puzzle
What is the process by which new seafloor is created?
Hot magma rising from below the crust
What is the rate of plate movement?
1-16 cm/yr
What is the mechanism driving plate movement?
Convection Currents
What is the process by which one plate is forced beneath another?
Subduction
What is the evidence for the fit of continents?
A close fit between coastlines of continents
What is the significance of the scars and scratches found on rocks in different countries?
They were created as glaciers slid along the surface.
What pattern is observed in the distribution of volcanoes, earthquake epicenters, and mountain ranges?
They are concentrated in a few areas of the world.
What type of plate boundaries are characterized by the Pacific Ring of Fire?
Transform and convergent plate boundaries.
What is a characteristic of the Mid-Atlantic Ridge?
It is a divergent plate boundary with the youngest crust.
What can be inferred from the presence of fossils of extinct plants and animals on different continents?
The continents were once connected.
What is the significance of the stripes found on rocks?
They indicate the presence of magnetic materials.
What is a characteristic of mountain ranges?
They are formed through the collision of plates.
Study Notes
Earth's Composition and Structure
- The Earth has a liquid outer core and a solid inner core composed of iron (Fe) and nickel (Ni)
- The mantle is composed mostly of silicates (Si and O)
- The crust is composed of rocks and minerals, with continental crust being low density and oceanic crust being high density
Lithosphere and Asthenosphere
- The lithosphere is the solid, rigid, and elastic layer comprising the upper mantle and crust
- There are 7 major plates: African, Antarctica, Eurasian, Indo-Australian, North-American, Pacific, and South American plates
- Minor plates include the Caribbean, Scotia, Arabian, Indian, Philippine, Juan de Fuca, Cocos, and Nazca plates
- The lithosphere floats on the asthenosphere and slides horizontally over it
- The asthenosphere is highly viscous, with high pressure and temperature
Continental Drift Theory
- Alfred Wegener proposed that continents were once a single large landmass (Pangea)
- Pangea broke into two smaller supercontinents, which eventually broke into continents
- Evidence includes the continental jigsaw puzzle, seafloor spreading, and fossil distribution
Seafloor Spreading Theory
- Harry Hess proposed that hot, less dense material rises from below the Earth's crust, creating a crack and magma flows out, cools down, and becomes new seafloor
Plate Tectonics Theory
- There are 7 major plates that move smoothly at a rate of 1-16 cm/yr
- Movement types: convergent, divergent, and transform
- Mechanism: convection current
- Evidence includes continental fit, similarities between rock layers, mountain ranges, fossils, glacial evidence, coral reefs, and seafloor magnetic stripes
Plate Boundaries
- Distribution of volcanoes, earthquakes, epicenters, and mountain ranges are concentrated in specific areas (Circum-Pacific Belt, Mid-Atlantic Belt, and Mid-Continental Belt)
Volcanic Belts and Mountain Ranges
- Volcanic belts: regions with high levels of volcanic activity
- Mid-Atlantic Ridge: part of the Mid-Atlantic Belt, along divergent plate boundaries, with youngest crust
- Pacific Ring of Fire: part of the Circum-Pacific Belt, with 75% of the world's active volcanoes, along transform and convergent plate boundaries
- Mediterranean Sea: part of the Mid-Continental Belt, along convergent plate boundaries
- Mountain belts: regions with mountain ranges, located along plate boundaries where collision of plates occurs
Quiz about the composition and layers of the Earth, including the core, mantle, crust, and lithosphere.
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