Midterm Geology Flashcards
(22 cards)
Define density
Density is the amount of mass in a given volume of a substance. Measures an object’s compactness
Density Formula
Density = Mass / Volume (D = m/v)
g/mL
g/cm3
What are the 4 main layers of the Earth?
Crust, Mantle, Outer Core, Inner Core
What are the other 3 layers of the Earth?
Lithosphere, Asthenosphere, Mesosphere
Describe Earth’s Crust
The outermost layer of the earth.
Solid, coolest, lowest pressure.
Describe Earth’s Mantle
The thick layer between the crust and the core.
Semi-solid, hotter, more pressure than the crust.
Describe Earth’s Outer Core
A liquid layer of iron and nickel generates Earth’s magnetic field.
Liquid, very hot, high pressure
Describe Earth’s Inner Core
The solid, innermost part of the Earth, is primarily made of iron and nickel.
Solid due to extreme pressure, hottest, highest pressure.
Describe the other layers of the Earth
Lithosphere: the crust and upper solid part of the mantle.
Asthenosphere: A partially molten layer of the upper mantle, located just below the lithosphere.
Mesosphere: the lower mantle, the part of the mantle between the asthenosphere and the outer core
Describe the changes in the layers of Earth as the depth changes
The deeper you get in the Earth, it’s hotter and higher pressure
Describe the lithosphere
The lithosphere is the outermost part of the Earth (where we live). It is broken into several moving plates that shape the ocean basins and carry the continents.
Describe plate tectonics
The Earth’s crust is broken into tectonic plates that float on the asthenosphere, a layer of molten rock in the mantle.
The plates move at different rates, sometimes colliding, separating, or sliding past each other. The type of boundary between plates determines the geologic processes and landforms that occur.
Divergent Boundary
Plates move apart (mid-ocean ridges, rift valleys). New oceanic crust forms.
Convergent Boundary
Plates move together and collide (mountains, trenches, volcanoes). Can create a subduction zone.
Transform Boundary
Plates slide past each other (can trigger earthquakes).
Formation of Earth’s crust
New crust forms at divergent boundaries.
Where is Earth’s old crust recycled
Old crust is recycled at convergent boundaries in subduction zones.
What causes tectonic plates to move?
Mantle convection, slab pull, and ridge push move the plates.
Why does the overall amount of crust on Earth stay the same?
Because new crust is created at divergent boundaries and recycled at convergent boundaries in subduction zones, so the amount never increases or decreases.
What is mantle convection?
Tectonic plates move primarily due to convection currents in the Earth’s mantle; hot magma rises from the deep within the Earth, cools and sinks, creating a circular motion that pushes the plates along with it, similar to how water circulates in a pot on a stove.
What is slab pull?
Slab Pull refers to the gravitational force that occurs when a dense oceanic plate (slab) sinks beneath another plate at a subduction zone, pulling the rest of the plate along with it, acting as a major driving force behind plate movement; essentially, the weight of the sinking slab drags the rest of the plate downwards due to its increased density compared to the surrounding mantle.
What is ridge push?
Ridge push is a force that pushes tectonic plates away from mid-ocean ridges. It’s a major driving force of plate tectonics.
