Geo Quiz (11/16/19) Flashcards
plate tectonics
the theory that earths outer shell is made up of individual plates that move, causing earthquakes, volcanoes, mountains, and the formation and destruction of areas of the crust
weathering
the breaking down of rocks
erosion
the moving of broken up pieces of rock
deposition
the building up of eroded materials in a new location
glaciation
the process of ice advancing and covering large areas of land
tsunami
a set of large ocean waves caused by an earthquake or other powerful disturbance under the sea
mid ocean ridge
a feature created by the spreading of the sea floor when two plates are diverging
subduction
the process in which one plate slides underneath another. the subducted plate moves unto earths interior and is recycled (it melts)
how to survive an earthquake: 9 steps
- if you are indoors, stay there
- if you are outside, get into the open, away from buildings, power lines, etc
- if you are driving, stop, but carefully
- if you are in a mountainous area, watch out for falling rocks, landslides, trees, debris, etc
- after the quake stops, check for injuries or seek aid or help
- if you can, put on a pair of sturdy, thick soles shoes
- check for hazards
- check food and water supplies
- be prepared for aftershocks
earthquakes
are the result of the motion of thin layers of the earths surface (moving plates) and material below
approximately ___ quakes occur annually around the globe
3000
focus
the pint under the earths surface where an earthquake occurs
epicentre
the point on the earths surface lying directly above the focus
seismograph
a device used to measure the movement of the earths surface resulting from the quake
seismogram
the paper that records the movement of the earth on the seismograph
mercalli scale
measures the intensity of the earthquakes and are ranked from 1-12. it is based on human observation
richter scale
measures the magnitude of the earthquake and is the more scientific scale used
•scale goes from 1.0-10.0 (logarithmic)
major earthquakes are classified as ______ on the richter scale
6.0
scientists use 3 criteria to classify volcanoes
1) the shape of the cone
2) the type of eruption
3) the contents of the lava
types of volcanoes
1) lava domes
2) lava fields
3) lava plateaus
4) tuyas
5) continental
6) composite
there are _ major plates
there are _ secondary plates
there are more than __ minor plates
7 major plates
8 secondary plates
more than 60 minor plates
mountain chains on the west, east, and northeast coasts were the result of
colliding plates
formation of canada’s fossil fuels (oil, coal, gas) were formed when
canada’s landmass was locates in a warmer, tropical climate
what was alfred wegeners theory
forces within the ground broke apart the landmass and moved them together, apart, and alongside each other
wegeners evidence
1) geological fit between south america and africa
2) same fossils of plants (ferns) and reptiles in both continents
3) similar mountain ranges (age and structure) on the east coast of canada/usa and the west coast of europe
4) similar scrapes and gouges on the rock surfaces of south america, india, australia, and south africa
divergent
- when 2 plates move apart
- occurs commonly along mid ocean ridges, but can happen on land also
- new areas of earths crust are cinstantly being created in this process alone 70 000kms of mid ocean ridges
- most of the worlds volcanoes occur along divergent plate boundaries
convergent (continental + ocean)
-rocks in oceanic plates ar emote dense than in continental plates
as a result, heavier oceanic plate slide under continental plates
-this process is called subduction
-in which the existing crust is “recycled” and being melted (which is balanced with the new crust being formed)
-subduction can happen smoothly, as oceanic plates move slowly over time.
-as it occurs, small quakes occur, that may not be detected by humans
- but in places where plates don’t move, plates that push against each other build up tension for centuries.
- when this tension is released, quakes can be very damaging (8-9 on the Richter scale)
BC hasn’t had a massive quake since
the 1700s
convergent (continental + continental)
when 2 plates run into each other, massive layers of rock fold, break, and are forced upward by immense pressures of the collision
this process creates many of the worlds most important mountain ranges (himalayas that includes everest)
transform
- plates are made neither larger or smaller
- plates move parallel, but opposite directions
- process happens very smoothly, with many small quakes
- sometimes(like in subduction zones) plates can lock up for many years until an enormous release of energy occurs, resulting in a damaging quake
- the worst quakes along transform zones are 5.5-7.5
