Restless Earth Flashcards
(33 cards)
Oceanic and continental plates differences
Oceanic: dense because it’s made of a rock called basalt which is darker and more dense than continental crust. Newer- less than 200 million years old. Thinner 50-100km
Continental : less dense and cannot sink, cannot be renewed or destroyed. Older- most over 1500 million years old. Thicker 200km
Earth is divided into..
7 major and 8 minor tectonic plates
Largest plates: Antarctic, Eurasian, North American plates
Constructive boundary
Where plates pull apart
Destructive boundary
Continental plate and an oceanic plate move together resulting in one plate skinning beneath the other. Plate being forced down causes severe earthquakes
Conservative boundary
Where plates slides past each other. Plates can get stuck which causes earthquakes
What are Fold mountains
Large mountain rangers where rock layers have been crumpled as they have forced together
Form at collision and at destructive margins
Fold mountains formation
- Rivers deposited huge quantities of sediments in depressions called GEOSYNCLINES
- Over million of years the sediments were compressed into sedimentary rocks such as sandstone and limestone.
- The plates moved together forcing the sedimentary rocks upwards into a series of folds
Fold mountains location and example
Usually form along coastlines of a country or the edge of a country within continents. Found in linear patterns along plate boundaries.
West of south (Andes) and North America (Rockies)
What r ocean trenches
Deep sections of the ocean, usually where an oceanic plate is sinking below a continental plate. Oceanic crust is forced to dip downwards at an ANgle at the subduction zone. DESTRCUTIVE MARGIN
Location and example of oceanic trenches
They are found on the borders of the Pacific Ocean , the ring of fire.
Mariana Trench
THE ANDES CASE STUDY
Farming and hydro
Farming : in Bolivia, subsistence farmers grow a variety of crops including potatoes on the steep slopes. Most crops are grown on the low valleys- soy beans rice and cotton. LLAMAS have been used for transport for hundreds of years as Machu Picchu is located in a remote area. They carry over 25% of their body Wright. Still used for meat, milk and wool. ADAPTATION to condition: they build terraces which are steps cut into hillsides to create areas of flat land- retain water and stop soil from moving downslope. Usually 2-6m wide.
Hydroelectric power: form mountains have steep slopes and narrow valleys which is an advantage for hydro power. Narrow valleys are more easily dammed than wider valleys. - the relief encourages rapid flow of water that is needed for generation of electricity. Glacial melt water is also ideal. THE EL PLATINAL PROJECT began in 2009, 2nd largest in Peru, dams the CAÑETE river.60% of SWITZERLANDS ENERGY comes fm hydroelectric power production.
What r ocean trenches
Deep sections of the ocean, usually where an oceanic plate is sinking below a continental plate. Oceanic crust is forced to dip downwards at an ANgle at the subduction zone. DESTRCUTIVE MARGIN
Location and example of oceanic trenches
They are found on the borders of the Pacific Ocean , the ring of fire.
Mariana Trench
THE ANDES CASE STUDY
Farming and hydro
Farming : in Bolivia, subsistence farmers grow a variety of crops including potatoes on the steep slopes. Most crops are grown on the low valleys- soy beans rice and cotton. LLAMAS have been used for transport for hundreds of years as Machu Picchu is located in a remote area. They carry over 25% of their body Wright. Still used for meat, milk and wool. ADAPTATION to condition: they build terraces which are steps cut into hillsides to create areas of flat land- retain water and stop soil from moving downslope. Usually 2-6m wide.
Hydroelectric power: form mountains have steep slopes and narrow valleys which is an advantage for hydro power. Narrow valleys are more easily dammed than wider valleys. - the relief encourages rapid flow of water that is needed for generation of electricity. Glacial melt water is also ideal. THE EL PLATINAL PROJECT began in 2009, 2nd largest in Peru, dams the CAÑETE river.60% of SWITZERLANDS ENERGY comes fm hydroelectric power production.
ANDES CASE STUDY
mining
Gold mining: Yanacocha,Peru. Disadvantage: rocks are sprayed with cyanide and therefore contaminates local water supplies. Campaigns to stop expansion of the mine to a nearby mountain cuz it is a site of spiritual importance to locals.
Copper mining: Chiquicamata, Chile. Mine is a large open pit of copper ore. Useful because it can be used to for electrical wiring cuz copper is a good conductor & resistant to corrosion.
Developments to open another copper mine in 2017 at cost of $42 billion- estimated to produce 140,000 tonnes of ore per day.
Mining Disadvantage : increasing amount of mines being opened - 40% of Columbias land are mines- means that it is disrupting Eco systems that people reply on. Land is being taken away from locals for mining so there’s a lack of harvest and plants grown for medicinal purposes.
Advantage: people are attracted to area cuz more jobs created. IN CAJAMARCA- inhabitants grew by 30,000 as 240,000 jobs were introduced in mining
Volcanoes what is it
A volcano is where magma erupts through the ground, usually happening at or near plate edges.
Found at constructive or destructive plate boundaries
Composite volcano
Steep sided with distinctive cone shape, high with narrow base
Secondary cones called parasitic cones formed when main vent is blocked
Explosive eruptions of lava and ash
e.g. SOUFRIÈRE HILLS
Shield volcano
Gentle slopes and wide base.
Usually non violent eruptions, frequent Eruptions of basic lava.
Lava flows at high speeds and for long distances before Cooling
E.g. MAUNA LOA
Volcano case study SOUFRIÈRE HILLS
Primary and secondary effects
Location: south of Montserrat. In Carribeans.
Cause : Montserrat is situated on destructive plate boundary. Atlantic plate forced under Carribean plate.
Primary effect: 23 people died in 1997, 2/3 of island as blankets in thick layer of ash, forest fires caused by pyroclastic flows
Secondary: ovr half of population left island and has not returned. Tourist industry is still suffering with few visitors. Southern area destroyed so people have to endure harsh living conditions in the north.
SOUFRIÈRE hills
Positive and negative impacts
Pos: lava and ash deposited during eruption breaks down to provide valuable nutrients for the soil- creates fertile soil. Volcano attracted more tourists to come.
Neg: many people died and many settlements and woodlands destroyed. Collapse of industry. Unemployment level rose from 7% to 50%
SOUFRIÈRE hills
Immediate and long term response
Immediate: Evacuation- People left the island completely- by November 1997, population had fallen from 12000 to 3500. Shelters built for evacuees. Charities set up temporary schools and sent emergency food.
Long term: British government gave £41 million for compensation and redevelopment. Islanders were offered £2500 each to relocate and permanently live in UK. Montserrat volcano observatory build to monitor volcano. Exclusion zone was Set.
Monitoring : volcanic Gas emissions measured by multi-component gas analyser system, which detects pre eruption degassing of rising magmas.
Super volcanoes
Much bigger scale than volcanoes, emit at least 1000km3 of material. They don’t look like normal volcanoes, they are large depressions called calderas. Don’t erupt often- only about 18 in 2 million years.
Effects of super volcano eruption
Full scale eruption would kill everything within an 100 mile radius, there would be ash 10 feet deep within an 1000 mile radius, which would cause earths temperature to drop because th ash would block the sun. Difficult to grow crops and people would die from starvation and toxic gas produced.
Monitoring volcanoes
SATELLITES- infra red detectors on satellites can pick up heat signals whcih indicate how close magma is to surface of ground.
GOLBAL POSITIONING SYSTEM- measures ground deformation caused by pressure of rising magma.
REMOTE SENSING- used to monitor gases. Chemical composition and amours of gas released by volcano may alter.
