My Notes for boundaries, absolute age, and climate change Flashcards
What are the 3 characteristics of matter/3 types of rock behaviour?
1) elastic
2) ductile
3) brittle
Rocks are…
ductile under___pressure
elastic under___pressure
brittle between___pressure
- low
- high
- high and low
The ___, particularly the___glows like a liquid.
- mantle
- asthenosphere
Where do diamonds come from?
the mantle
What are the 4 points of evidence for pangea with rock matching?
1) Archean/younger boundary in South America and Africa
2) Late paleozoic glacier
3) fossils in Gwondana
4) Appalachian/Caledonian Mountain Chain
When was there a massive glacier?
late paleozoic
What are the 2 points of evidence for glaciers?
1) glacial striations- pebbles get picked up by glacier and as it flows they scratch the surface of the rock. Track the direction of flow
2) glacial deposits- as glacier flows, it picks up debris. When ice melts, this debris is left behind, called till. Ancient deposits.
Pangea began to form around___Ma.
300
What created Pangea? Where did the Caledonian Orogeny take place? When did the final orogenic effects end?
Plate collision and the Caledonian Orogeny takes place along part of the Convergent Plate Boundary. Final orogenic effects end ~250 Ma
When was the break up of Pangea?
180 Ma
When was the amalgamation of Rodina?
1000 Ma
When was the breakup of Rodina?
700 Ma
When continents break up and collide,___is changing at the same time.
Climate
What is lateral continuity?
Layers aren’t just on surface of this hill, they go through body of hill and project through others. Some may have been eroded away. we run into this when we drill holes. Eventually the layers run out, but until then, they are laterally contingent.
Where is the magnetic axis alway at on average?
The axis of spin (the geographic north pole)
How many km does the magnetic pole move each year?
several
What is each spot the magnetic pole lands on called?
virtual geomagnetic
What tracks continent movement?
polar wandering curve
What carried old magnetic information with it when it moved?
continents
What are divergent plate boundaries?
plates moving away
What are convergent or collisional plate boundaries?
plates coming together
What are transform plate boundaries?
plates moving sideways
Average rate of continent movement? What is the range of continent movement?
Average = 2 cm/year Range = 0-10 cm/year
Where do earthquakes occur?
at plate margins
Does the entire fault slip at the same time an earthquake slips?
no
Where is the centre of earthquake slip?
Where the energy is released
How is absolute plate movement determine?
- from satellite map
- geological past –> apparent polar wandering curves
What do divergent plate boundaries result from?
earthquakes, MOR, rift valley, etc.
Continental breakup =
ocean formation
At what depth is there partial melting during subduction with c.p.b?
At about 200 km depth there is partial melting with subduction
What are trenches on the ocean floor caused by?
subduction
What are belts of volcanoes around pacific always beside?
an ocean trench
What are the two types of volcanic arcs?
- land
1) volcanic continental arcs - sea
2) volcanic island arcs
Are volcanoes alway inside or outside of the arc?
inside
Where does almost all of Earth’s visible volcanic activity take place at?
The Ring of Fire
How deep is Mariana’s Trench?
13 km deep
What are sea mounts? Which have flat and pointed tops?
- guyot
- abyssal hills
- coral reef (atoll)
- some have pointed top –> under waves
- some have flat top –> over waves
What are the two causes of volcanism?
1) divergent plate boundaries (ex. Iceland) –> melting at depth caused by decompression
2) convergent plate boundaries –> subduction process (heat generated) raise temperature –> melting
What leads to the production of orogenic mountain belts?
convergent plate boundaries
What is an orogen created from?
geosyncline
How thick are geosynclines?
30 km thick
How old are geosynclines?
several million years
What are geosynclines made up of?
sediment and volcanics
What are the 4 parts the tectonic uplift process?
1) folding
2) thrust faulting
3) intrusion
4) metamorphism at depth (once deeply buried rock now on Earth’s surface –> like precambrian shields)
What drives organic evolution?
As continents move around and change positions, they sometimes move into new climate zones. When orogenic mountain belts form, they change the environment. Steady ongoing position of seafloor and continents for last four billion years is the driving force behind organic evolution.
There are some places where a “hot spot” comes from the___mantle.
lower
Do hot spots interfere with plate movement?
no
What are the three ways that hot spots can form?
1) Erupt at surface with a volcano.
2) Can also form by extra fast rising bit of plume that will cause plate separation
3) Can also punch through continents
What creates plumes and convection cells? What does this lead to the creation of?
Combination of heat and gravity creates plumes and connection cells which creates what we see on the Earth’s surface (topography, volcanoes, organic evolution, etc.).
What is absolute geological time?
The time when some event occurred
-years ago
What are the 4 measurements of absolute time?
1) *radioactive decay of isotopes
2) tree rings
3) varve
4) layers in glaciers
How to radioactive isotopes make a geological clock?
because you can measure the rate of decay
What does decay equal with radioactive isotopes/
- alter to some stable daughter element
- atomic nucleus deconstructs itself –> emits particles –> protons and neutrons
What is the half life of a radioactive isotope?
how long it takes for one half to decay
How can we calculate absolute age with radioactive isotopes?
By looking at rate of daughter-parent we can calculate the age.
What does potassium convert to when it decays?
Argon
What is argon?
- does not combine chemically with anything
- noble fas
^40K –> ^40 Ar has 1___proton and 1___neutron
- less
- more
Is Ar radioactive or radiogenic?
radiogenic
What does it mean to be radiogenic?
Form from radioactive decay of something
What is the only way that Ar is produced?
From the radioactive decay of something (like K)
Why is zircon important?
Because some of the zirconium (which zircon contains) is replaced chemically with uranium
What elements is organic material made up of?
C H O N
What is bracketing?
date: lave
bracketed: fossil
date: lava
What is almost the only way to know the absolute age of a fossil?
by bracketing
What wer ehe age of the rocks that have all the potash that turned Saskatchewan into a have province?
Devonian
What is the other way to date fossils?
A few fossils found in volcanic ash (or rarely lava) can be dated by dating volcanic rock.
When was the start and the end of the Pleistocene?
Start: 2 Ma
End: 10 Ka
When was the time of rapid global cooling when glaciers began to spread out?
the Pleistocene
During the Pleistocene, glaciers have gone from covering___% of land to___% now.
- 30
- 11
What is the period at the end of the Protozoic?
the Edicaran
What is the phrase to remember geological periods?
Combinations Of Strong Drinks Cause People To Jump Consequently Topping Quickly
How many years ago did the last major ice age peak?
22 000 years ago
What is the equator warmer?
because of the axis of spin (less surface area)
What happens as layers of a glacier get compressed vertically?
Ice flows out and spreads out if it is not confined.
What happens if glacial ice is confined (flow)?
It flows in one direction
What can you use the O bubbles in glaciers to determine?
temp of air when it snowed
What can you use the ice of a glacier to determine?
The temp of snow
What can you use volcanic ash for with glaciers?
You can do K-Ar date
