Exam Questions Flashcards
(13 cards)
Outline how the Richter scale is used to measure earthquakes
The Richter scale uses information collected by seismometers
That record the strength of shock waves and amount of movement
A seismograph is produced showing a ‘line graph’ of the waves
This used to assign a number in the Richter scale between 0-10 (but there is no upper limit)
What is the difference between the focus and the epicentre of an earthquake?
Focus is within the earth’s crust where the earthquake begins
Whereas the epicentre is the point on the earth’s surface directly above the focus
Describe how a river transports it’s load
A river transports large boulders via traction - where material is roller along the bed
Smaller pebbles are carried by saltation - a leapfrog movement
Fine material is carried within the water itself - this is suspension
Some rockers are soluble and will dissolve - such as limestone
Outline one reason why he largest earthquakes do not always cause the most deaths
Population density may be low so few people present in the danger area
Some areas may be poor and so building just cola or killing people
What are fold mountains?
They are a large ranges of mountains where different rock layers have crumples into anticlines and sync lines as they have pushed together
Characteristics of igneous rockes
Formed from cool magma
They mY have been cooled within the crustContain many interlocking crystals and as a result are tough and resistant to erosion
Describe the location of ocean trenches
Often near to fold mountains
Explain the formation of limestone pavements
Limestone is calcium carbonate
Rainwater mixes carbon dioxide in the atmosphere as it falls and becomes weak carbon acid
Calcium carbonate is insoluble in this, the process of carbonation takes place
As limestone has joint and is permiable, the water enters via these joint and the joint get bigger as limestone solution is made and the dissolved limestone is removed
This results in the enlarged gals between the limestone blocks
The surface of the clients is smooth due to the water but is often uneven and pitted foodie to the impact of solution where he water sits in hollows
Describe how the shape if a river valley changes downstream
Valley is becoming wider, with a flat valley floor in contrast to the river taking up most. If the valley floor near the source
The steel valley sides that characterise the upper course reduces in height and steelers as the profile becomes an open U from a V shape
And with an absence if clear valley sides in the lower course
Outline the characteristics of a shield volcano
Flat top Low lying Broad base Gentle sloping sides Made of runny lava
What is the formation of a composite volcano
They occur at destructive plate margins
Here plates move towards each other due to convection currents
Pressure builds up over a long period of time as the denser oceanic plate slides beneath the continental plate
Melting of this occurs in the subduction zone due to friction and heat and the crust becomes magma
This process causes a build-up of pressure which is released in an explosive eruption
Give volcanos that are formed from sticky slow flowing lava and ash often in alternate layers along a line of fault
Contrast the position of granite and chalk on the geological time scale
Granite is an older rock than chalk
Chalk is formed during the Cretaceous period, around 65-145 million years ago
Whilst granite formed 280 million years ago Permian
Thus granite is at least twice as old as chalk
Outline the characterises of Carboniferous limestone
Remains of Dead Sea creatures
Permeable rock
Is formed in layers
