Rock Flashcards
What is a seismologist?
a scientist who studies earthquakes or similar disturbances and the effects they produce on the earths crust.
why does the earths crust bend and crack
Due to tectonic forces or convection currents
What are convection cells? What causes them?
Convection cells are caused by the uneven temps inside the earth. They move the plate. Hot areas in the core
How thick is the earths crust?
Skin of an apple compared to the apple
Contentianl drift? what is it?
Alfred Wegner. 300 million years ago the continents which were in constant motion collided to for one large land mass called pangea.
Pangea?
Means “all land” the super continent that included all the earths land mass
4 reasons Pangea?
1 similar fossils of plants and animals
2 the jigsaw between south american and africa
3 similar mountians in age and structure, both sides
4 how could ice sheets have developed in places that are so warm today
name 6 major plates?
North american plate, african plate, pacific plate, south american plate, eurasian plate, antarctic plate
Convergent (2 types)
when 2 plates collide with each other and the denser one gets pushed down into the mantle called subduction zone.
an example of convergent is where the Juan de Fuca plate subjects under the NA plate
another example when 2 plates collide the forces push both plates up, for example the himalayan mountains
Divergent
when two plates move away from each other creating a magma ridge for example the mid atlantic ridge
Lateral
When 2 plates move past each other laterally for example the pacific and NA plate creating the san andres fault
why do earthquakes occur? were? results?
when the tectonic plates move causing friction and often jam for a long periods of time occur close to the edge of the tectonic plates results can destroy building,homes cities
Richter scale how does it work
a scale on which earthquakes are measured. numbered 1 to 10 logarithmic 8 being higher 7
where do most volcanos occur? Why do they occur there?
most volcanos occur close to subduction zones or where one plate goes lower then the other and melts. This creates excess gases which which reach the surface through a crack often explosively
Composite Volcano
large cone shaped mountain, composed of lava, cinders and ash
eg. mount fuji japan
shield volcano
large in width not high
composed of lava
eg. mauna loa Hawaii
Cinder Cone Volcano
Similar shape to composite but smaller
composed of cinder and ash
eg. Paracutin mexico
Weathering
The breakdown of rock material into smaller places
Erosion
the movement between weathered material
Deposition
The replacement of weathered material
The earths physical landscape is the result of conflict between forces
the earths surface is always being changed by weathering,erosion and deposition and the aways moving tectonic plates
Precambrian
-Canadian shield and Australian shield formed
Palaeozoic
- Appalachians are formed
- Large parts of NA are covered by shallow seas
Mesozoic
- formation of the rocky mountains begins
- Innuations mountains are formed
Cainozoic
- Formation in the rocky mountain is completed
- Ice sheets covered most of NA
which era lasted the longest
Precambrian era
Which era are we living in
Canozioc
What did the original canadian shield look like? What does it look like now
it used to have mountians as high as 12 000 m above sea level. now has hills less then 500m high, the eroded material was deposited into the ocean now forming the bedrock of every province
Sedimentary rock
heat + pressure put on sediments ex. sandstone
Igneous
cooled lava ex granite
metamorphic
heat and pressure put on rock changes its composition e.g. shale to slate, limestone to marble
how can one type of rock form another
the rock cycle
heat, pressure, melting and weathering and erosion put on rocks to form different kinds of rocks
where was north america in the Palaeozoic era? how has this helped canada economically
close to the equator. huge swamps grew in the warm climate produced sea creatures and living organisms, later becoming the oil and gas in AB BC and SK
what catastrophe happened at the end of the paleozoic era?
great extinction
pangea broke up in which era
paleozoic and early Mesozoic
what catastrophe happened at the end of the mesozoic era?
another massive extinction
in which geological era did the latest ice age happen? how many periods of large scale glacial activity was there?
Cainozoic era, 4 periods
when did the last ice age end? how much of the earth is covered by ice?
6000 years ago, 10%
geological effects of glaciers
CAN shield was rounded by glaciers
formed valleys and lakes of today
