I've Got Geologic Time
What does the Geologic Timeline help us visualize and segment?
The history of the Earth since its formation.
Movement of the Earth's mantle causes what to happen to the crust?
What is another name for transform boundaries?
Faults (Fault lines also acceptable)
Abyssal Plain
Name the 4 oceans from largest to smallest. Then name the 5th "ocean" used by oceanographers.
Pacific, Atlantic, Indian, Arctic.
Southern.
When in Geologic Time did the oceans form?
The Hadean Eon
(Half points for Hadeon without Eon)
Draw a picture of the four layers of Earth discussed in class. Include which layers are liquid and which layers are solid.
Inner core- solid
Outer core- liquid
Mantle- liquid
Crust- solid
What is formed by divergent plates?
Mid-Ocean Ridge
How do submarine canyons form?
Submarine canyons form when the continental shelf is located above sea level. When exposed, rivers and glaciers erode the land and cause canyons to form. When sea levels rise, these canyons become submerged and are now Submarine Canyons.
What are the two types of Biogenous sediment? (Hint: The two types of Oozes)
Calcareous Ooze and Siliceous Ooze.
When on the Geologic Timeline is there fossil evidence of all the major animal phyla forming?
During The Cambrian Period
(Also acceptable: The Cambrian Explosion)
How are tectonic plates, oceanic crust, and continental crust related?
Tectonic plates are made up of pieces of Earth's crust and can be made up of Oceanic Crust OR Oceanic & Continental Crust. There are no plates that are ONLY Continental Crust.
Name the 3 types of tectonic plate movements and their directions.
Convergent- plates move towards each other
Divergent- plates move away from each other
Transform- plates slide past one another (parallel)
What is a guyot (gee-oh)?
A guyot is a flat topped seamount that was once a volcanic island. The landmass sank down into the mantle due to its weight or are is underwater once again due to rising sea levels.
How do we know that Earth has gone through periods of magnetic reversal?
Discovered by studying the magnetism of sea floor rocks. Many rocks contain tiny magnetic particles. When molten, the particles are free to move and act like little compasses pointing towards magnetic North. When the rock cools, the particles lock in place.
Scientists found bands of sea floor where the magnetic particles in the sea floor rock pointed South, not North. Indicates a magnetic reversal at the time of their cooling! There are many bands of magnetic "normalcy" and magnetic "reversal" believed to be caused by the motion of liquid iron in Earth's outer core.
Why is it difficult for geologists/scientists to study the Hadean Period?
The are no rocks from this eon present today to study- they were all molten or have been recycled through the magma layer and crust/plate movement.
Between oceanic crust and continental crust which is:
Thinner?
Less Dense?
Made primarily of Basalt?
Which formed first?
Which has the oldest samples?
Thinner? Oceanic
Less Dense? Continental
Made primarily of Basalt? Oceanic
Which formed first? Oceanic
Which has the oldest samples? Continental
Describe what happens to the plates during each example of a convergent plate boundary.
Oceanic vs. Continental
Continental vs. Continental
Oceanic vs. Oceanic
Oceanic vs. Continental: Oceanic plate subducts under the continental plate.
Continental vs. Continental: Neither plate truly subducts.
Oceanic vs. Oceanic: One plate subducts under the other.
Draw a picture of continental crust (with the three components of a continental margin) meeting oceanic crust.
Continental crust (Continental shelf, Continental Slope, Continental Rise) Oceanic crust. See notes for picture.
Explain how a hydrothermal vent forms.
Also explain specifically how the hydrothermal vent chimney forms.
As the sea floor spreads, cracks are created in the surface that allows water to seep towards the mantle. The mantle heats the water and this extremely hot water forces its way back to the surface and emerges through structures known as hydrothermal vents.
Hydrothermal vent chimneys for when water picks up minerals as it travels through the crust & mantle. Minerals remain dissolved in hot water but solidify when exposed to the cold deep sea. Solid minerals deposit and form chimney like vent structures as they build up over time.
Describe the condition of Earth in the early Hadean vs the mid Hadean vs the late Hadean?
Were there oceans? Were the oceans deep or shallow? Were there land masses? What types of crust were present?
Early Hadean: Molten magma surface, no oceans, no land masses (Earth's surface was too hot!)
Mid Hadean: Shallow to moderately deep oceans, no land masses, oceanic crust present (no continental crust)
Late Hadean: Deep Oceans, Land Masses, both oceanic and continental crust.
Describe how a convection current works using the Earth's crust, mantle, and core.
Magma (molten rock) is hottest near the heat source (Earth's Core)
As magma gets hotter it rises to the surface (Earth's Crust) where the temp is cooler.
The magma that rises to the surface pushes magma that has cooled from having spent time at the surface back down towards the heat source.
Motion of magma creates a current that “feeds” itself so long as the heat source is present.
Describe what is formed by each example of convergent plate boundary.
Oceanic vs. Continental
Continental vs. Continental
Oceanic vs. Oceanic
Oceanic vs. Continental: (Oceanic plate subducts under the continental plate) Inland volcanic arc forms
Continental vs. Continental: (Neither plate truly subducts) Mountains form
Oceanic vs. Oceanic: (One plate subducts under the other) Trenches form and volcanic island arc forms.
Compare and contrast Active and Passive plate margins.
What kind of plate boundaries?
Lots or Little amount of continental shelf?
Moderate or Steep continental Slope?
Continental rise Present or Absent?
Geologically Active or relatively Inactive?
Passive: Divergent plate boundaries. Lots of continental shelf. Moderate/ continental slope. Continental rise present. Relatively geologically inactive.
Hydrothermal vents appear to be smoking because the minerals that have dissolved in the water heated by the mantle rapidly precipitate (turn solid) when exposed to the cold sea floor conditions.
Black Smokers- color caused by sulfides
White Smokers- color caused Barium, Calcium, Silicon