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Faults & Boundaries
Transcript of Faults & Boundaries
“The structure of the earth's crust and mantle with reference to the theory that the earth's lithosphere is divided into large rigid blocks (plates) that are floating on semi-fluid rock and are thus able to interact with each other at their boundaries, and to the associated theories of continental drift and seafloor spreading” (Collins Concise English Dictionary) Type of Boundaries Convergent Divergent Transform Boundary Formations & Features Ocean Ridges Seafloor Spreading Island Arcs Fold Mountains Ocean Trenches What is a Fault? A fault is a fracture or system of fractures along which Earth moves. The movement along these faults result in earthquakes caused by stress in the Earth's crust exceeding the strength of the material.
There are 4 types of faults. Types of Faults Normal Fault Reverse Fault Thrust Fault Strike-Slip Fault Formations & Features Block Mountains Rift Valleys What is Folding? Types of Folding Syncline Anticline Monocline Canadian Impact Ottawa-Bonnechere Graben Rocky Mountains Earthquakes & Tsunami Threats Famous Canadians Dr. George Mercer Dawson Dr. Thomas C. Hanks Careers Geologist Geophysicist Seismologist Volcanologist Civil Engineer Land Surveyor Work Cited Questions Thank You For Listening! Convergent boundaries occur when two plates move toward each other and hit each other.
As a result, volcanoes and earthquakes occur.
There are three types of convergent boundaries: Graben & Horst http://media.pearsoncmg.com/bc/bc_0media_geo/interactiveanimations/057_MotionAtPlate_SP_GL_Stu.html?te10#/ Oceanic-Oceanic Continental-Continental Continental-Oceanic Continental-Continental: occurs when two continental plates collide with each other.
They buckle and compress which forces one plate to slightly go under the other causing folding.
They also form extensive mountain ranges like the Himalayas. Oceanic-Oceanic: occurs when two oceanic plates collide with each other. One plate is usually subducted under the other forming oceanic trench.
For example, the Marianas Trench was formed when the Philippine Plate was subducted under the Pacific Plate.
It creates island arcs due to the spherical surface of the Earth that are formed from volcanoes. Continental-Oceanic: occurs when a continental plate collides with an oceanic plate.
The oceanic plate will always be subducted under the continental plate since it is more dense.
The continental plates are then lifted upwards forming mountain ranges like the Rockies. Divergent boundaries creates zones when two plates move away from each other.
When the Earth’s lithosphere is pulled apart, it breaks along parallel faults that will cause it to tilt slightly outwards.
The sinking lithosphere will then form a rift. The magma then will rise from the mantle filling the cracks.
As the magma cools down, a new crust will start to form and as the magma reaches the surface new volcanoes can form.
Sea floor spreading is created from divergent boundaries in which the the magma creates new land under water Transform boundaries are places where two plates slide horizontally past each other.
Although transform boundary itself are considered non-destructive, the sliding motion of the transform boundaries can cause destructive earthquakes.
San Andreas fault is an example of this which was a result of the North American Plate sliding against the Pacific Plate.
They are also found in deep oceans and they form zigzag shapes. These are the upland areas formed by the buckling of the earth's crust attributed to convergent boundaries
Fold mountains occur at destructive regions on oceanic crust that is subducted underneath a continental plate, which can force it to crumple and uplift - the resulting folding and faulting results in the formation of a mountain chain roughly parallel to the oceanic trench - e.g. the Andes Mountains.
Fold mountains at a collision zone occur as the colliding plates resist subduction and uplift occur with folding and faulting - e.g. the Himalayas. It is the process by which the ocean floor is extended when two plates move apart at a divergent boundary.
Seafloor spreading and divergent boundaries occur where two convection cells meet and where the heat rises through a central point
As plates move apart the rocks break and cracks form. Magma then rises through the cracks and seep out onto the ocean floor. It then cools and solidifies to basaltic rock adding to the the edges of the of the plates, and the sea floor spreading outwards. When the magma accumulates along then, a long chain of mountains form gradually on the ocean floor, which is called an oceanic ridge
Ocean ridges, occur in a linear pattern, usually through the middle of oceans (e.g. the Mid-Atlantic Ridge)
As magma rises at this point (the rising limb of a convection cell), the rising magma causes the lithosphere to dome up creating the ridge and where tensional forces, creates weaknesses in the crust, magma erupts forming volcanoes which further build up the ridge.
The East-Pacific Ridge is an anomaly from the pattern of mid-ocean ridges - which can be explained by the fact that the rising limb of the convection cells is in the asthenosphere These are often found in a linear pattern located just offshore, at a convergent boundary.
Deep oceanic trenches form at destructive regions where oceanic lithosphere is subducted into the asthenosphere below of the continental shelf extending offshore.
The long and narrow oceanic trenches are formed during and mark the place where the ocean floor is deepest, roughly 10 km below sea level
The most discernible example is of the Marianas Trench, which is the deepest part of the world`s oceans located in the western Pacific Ocean, spanning about 2,500 km long, 69 km wide, and 10 km deep. Tend to form a linear pattern, in an "arc-shaped" due to the curve of the Earth
An island-arc is a chain of volcanic islands that form at a destructive boundary where there is the convergence of two oceanic plates.
During subduction, the subducting plate is melted caused by the interior heat, friction and pressure thus creating a magma source.
The light, less dense magma rises to the surface and erupts to form sub-surface volcanoes
Eventually these volcanoes grow through successive eruptions to above the height of sea-level forming a chain of volcanic islands which is known as an island-arc.
They can also form from hot spots in the mantle, like the Hawaiian islands. A normal fault drops rock on one side of the fault down relative to the other side.
They move partly horizontally and partly vertically.
As shown on the diagram, it is a fault in which the hanging wall has moved downward relative to the footwall.
Occurs where two blocks of rock are pulled apart; by tensional forces. In a reverse fault, one block of rock is pushed upwards relative to the other block.
They move partly horizontally and partly vertically.
As shown on the diagram, it is a fault in which the hanging wall has moved upward relative to the footwall.
Occurs where two blocks of rock are pushed against each other; by compression. In strike-slip fault, surfaces on opposite sides of the fault slide against each other in the opposite direction horizontally and parallel to the fault.
Can be described as “Side-by-Side” motion.
Strike-slip faults are described as “right-lateral” or as “left-lateral” depending on the movement of the block opposite to the one looking at it.
When this faulting occurs on plates it is known as a transform boundary, for example the San Andreas Fault line. In a thrust fault, the fault plane is inclined at an angle equal to or less than 45°
The upper side of the block has been pushed by compression creating a thrust fault.
There is no difference between a thrust fault and a reverse fault when it comes to their motion. However, a thrust fault have a shallow angle when compared to a reverse fault. These are formed when the pressure forces a whole rock mass to break away from another which creates a fault.
As one side rises, the other side sinks and the Earth’s crust starts to fracture.
The block mountains have a steep front side and a sloping back side.
Examples: The Harz mountains in Germany, and the Sierra Nevada in California, U.S. http://media.pearsoncmg.com/bc/bc_0media_geo/interactiveanimations/020_DivergBound_SP_GL_Stu.html?te10#/ Rift valleys are linear-shaped lowlands between highlands or mountain ranges as a result of faults.
Occur in oceanic or continental plates when they break apart.
The East African Rift valley is an example where two plates moved apart forcing the ground to sink forming the valley. Examples for Horsts are: the Black Forest in Germany, and the Vosges mountains in France. Regions that lie between normal faults.
A horst is a block that has been pushed upwards by faulting while a graben is a block that has been pushed downwards by faulting.
May range in size from blocks a few cm wide to tens of kms wide, and the vertical movement can go up to several thousand feet. Graben Horst Examples for grabens are: the Dead Sea in Jordan, and the Ottawa Graben in Canada. A block mountains is an example of a Horst in which the Earth’s crust has risen up. A rift valley is an example of a Graben in which the Earth’s crust has dropped down. August 1, 1849 – March 2, 1901
He was Canadian geologist and surveyor and the eldest son of Sir John William Dawson
Dawson studied geology and palaeontology at the Royal School of Mine at Imperial College London, UK.
Dawson started his work in the early 1870’s performing extensive surveys of western Canada, including the International Boundary Survey. Through the the 1880’s he was responsible for mapping major mountains by the Canadian government. He discovered some of the peaks including Mount Assiniboine (3,618m) and Mount Temple (3,543m).
He led an expedition to the Yukon, developing maps for the region. Dawson City and Dawson Creek, B.C. are named in his honour.
He became director of the Geological Survey of Canada in 1895, he died six years later of acute bronchitis. He is Canadian born, naturalized American citizen seismologist.
He works for the US Geological Survey (USGS) in Menlo Park, California. Dr. Hanks is a member of the Seismological Society of America, the American Geophysical Union, the Earthquake Engineering Research Institute, the Geological Society of America, the Peninsula Geological Society at Stanford, and many related geological societies. Dr. Hanks has authored dozens of scholarly papers in strong-motion seismology and tectonic geomorphology.
In 1979 the Japanese-American seismologist Hiroo Kanamori and Dr. Hanks suggested the use of the Moment Magnitude scale to replace the Richter magnitude scale for measuring strength of earthquakes. "3 Types of Plate Boundries." Plate Tectonics. N.p., n.d. Web. 6 Apr. 2013. <http://adjr06.tripod.com/id8.html>.
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Skill/Specialty. " Geophysicist Salary, Average Salaries | PayScale Canada." PayScale - Salary Comparison, Salary Survey, Search Wages. N.p., n.d. Web. 6 Apr. 2013. <http://www.payscale.com/research/CA/Job=Geophysicist/Salary>.
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"What is a seismologist?." Earthquakes Canada / Seismics Canada. N.p., n.d. Web. 6 Apr. 2013. <http://www.earthquakescanada.nrcan.gc.ca/info-gen/seismolog-eng.php>.
"faulting.3gp - YouTube." YouTube. N.p., n.d. Web. 6 Apr. 2013. < Geologist studies the matter which makes up the Earth, the processes and history involved which shaped it.
Examine and identify rocks and minerals. Prepare maps that show rock types and geological structures
Earnings range from $35,000 to $150,000 a year or more and depend on location, experience, and education
At minimum a bachelor’s degree in geology or a related field
Many senior and research positions require a master’s degree or PhD Land surveyor use specialization equipment and computerized mapping systems to analyze land surfaces
Land surveyors in the arctic are used to analyze the elevations and structures which make up this landscapes.
Average salary ranges from $35,000 to $100,000 a year .
A diploma or bachelor's degree is require in surveying engineering, and license to practice in specific jurisdictions Civil engineers help design and build the structures all around us, including buildings, bridges, dams, highways, railways, and sewers.
In places around the world they must build structures which are able to withstand earthquakes cause by faults and boundaries
Salary earnings ranges from $40,000 to $120,000, with average salary of a civil engineer in Canada being between $76,000 to $86,000.
The minimum requirements for an entry-level position as a civil engineer is a bachelor’s degree in engineering.
For more senior and better paying positions requires becoming a Professional Engineer (P.Eng.), which includes spending a minimum of 4 years under senior supervision and the completion of a provincial licensing exam, to earn that title.
Graduate and post-graduate are also necessary for more senior positions. Volcanologist is a person who studies the formation of volcanoes, their current and historic eruptions, and to possibly predict future eruptions.
To become a volcanologist one must start their career by getting a bachelor's degree in geology or related field, there is no specific qualifying degree to become a volcanologist.
The minimum educational requirements, at the entry-level, is a master's degree in earth science or related field, and for higher posts, one needs a Ph.D.
Entry-level volcanologists can earning around $40,00 and with more experience senior volcanologists can earn anywhere up to $90,000. Geophysicists use the principles of physics, mathematics and geology to study the surface and internal composition of the earth through measuring responses to seismic and electromagnetic waves.
The average pay scale of a geophysicist ranges from $50,000 to $160,000, with the median being around $77,000.
The minimum education requirement for exploration geophysicists is a Bachelor of Science (B.Sc.) degree in geophysics or a related science.
A master's degree (M.Sc.) may be preferred; a doctoral (PhD) degree is essential for research and senior positions Seismologists are Earth scientists, specialized in geophysics, who study the genesis and the propagation of seismic waves in geological materials.
Seismologists study the relation between faults, stress and seismicity and collaborate with engineers in an attempt to minimize the damage caused to structures.
A university undergraduate degree is necessary, and Masters studies or Doctoral work are significant assets for more advanced research and senior positions.
The average salary pay scale of a seismologists ranges from $54,000 to $113,000 Faults and Boundaries has had a significant impact on the people of Canada and its landscape.It has significant impact on this region in particular and in regions across Canada, and has a significant impact on people living in Canada. This is an ancient rift valley in the Canadian Shield located in Northeastern Ontario and Southern Quebec spanning over 700 kilometres joining the St. Lawrence rift valley system on the east past Lake Nissiping on the west.
This rift valley was formed when the Earth`s crust moved downward between two major fault zones when the Earth's known as the Mattawa (north) and Petawawa faults (south). These faults are still active and periodically releasing stress cause minor earthquakes.
The mountain ranges are left on either side of the fault, on the north side it is the Gatineau Hills, and on the south side it is the Calabogie peaks.
This Graben is commonly referred to as the Ottawa valley. The western coast of Canada is located on the Pacific Rim of Fire, a location on Earth where significant amounts of seismic activity occurs due to the plate boundaries encompassing the Pacific Plate.
As a result western Canadian is at greatest risk for seismic activity in all of Canada, which has led to safe measures and warning systems being set in place to protect the people living in these regions.
Tsunamis are a series of ocean wave generated by seismic activity below on the seafloor, these waves are much faster and higher than tidal waves making them very dangerous and deadly.
The British Columbia provincial government has measures set in place for people to evacuate coastal and low-lying regions to higher elevation and further inland. The mountain range in western North America stretching almost 5,000 km from north British Columbia to to New Mexico, United States
This mountain range formed about 55 to 88 mya, when multiple oceanic plates comprising of the Pacific Plate converged and subducted under the less dense North American continental plate.
The significance of this convergent boundary was that the subduction of oceanic and continental plate was shallow, not only causing the very high mountains but also causing the Rockies to be farther inland.
On eastern Canada fold mountains are also found, called the Appalachian Mountains. The have been eroded significantly when compared to the Rockies On the south side of the mountains was continental sea the deposit sediments in this area About 175 million years ago the land surface to the south side collapsed when the shale and carbonate floor gave weigh, creating two faults. Around 1 billion years ago this region was consisted of volcanoes which over hundreds of million of years erode to a mountain which today is known as the Gatineau Hills. The subduction of the plates created a volcanic arc spanning western North America, which combined with folding formed the early igneous rock mountains probably up to 6,000 metres (as high as the Himalayas). Over time these volcano were slowly eroded and sculpted by glaciers and other forces that form the Rockies to its present state. Unlike faulting, folding is the process of bending of the rock. Folding is when something starts to compact and to bend over upon itself.
Both caused by stress in the Earth's crust exceeding the strength of the material.
Folding tends to occur at slower rates of stress, at higher pressures and temperature at greater depths all of which prevents formation of fractures within the material leading to ductile deformation which is why the rocks can fold rather than break.
Folding usually occurs at a convergent between two continents or a continental and oceanic plate.
Fold mountains are often formed from sedimentary rocks and strata. Anticline is a fold that is convex up and has its oldest beds at its core
They are usually recognized by a sequence of rock layers that are progressively older toward the center of the fold because the uplifted core of the fold is more eroded . Syncline is a fold with younger layers closer to the center of the structure.
Synclines are recognized by a sequence of rock layers that grow progressively younger, followed by the youngest layer at the fold's center or hinge, and by a reverse sequence of the same rock layers on the opposite side of the hinge. Monocline is a step-like fold in rock strata consisting of a zone of steeper dip within an otherwise horizontal or gently-dipping sequence.
Usually occurs when differential compaction over an underlying structure, particularly a large fault at the edge of a basin, over time the amplitude of the fold will die out gradually upwards