1
Name two physical factors that influence the breaking of rocks into smaller pieces.
Changes in temperature and pressure.
The solid outer covering of the earth which envelopes its interior portion is called the crust. Its average thickness varies from____ to ____ kilometres.
5 to 40 kilometres
Define Erosion
The act of carrying away the weathered particles from one place to the other is called erosion.
Sand dunes are formed by:
Wind
The mantle lies between:
Crust and Core
The movement of tectonic plates is caused by?
convection currents
What is the approximate thickness of the Earth's core?
About 3,500 km.
Define Weathering
The process by which the rocks exposed on the surface get broken into smaller pieces in situ (in the same place) is known as weathering.
__________ is one of the most important scientific theories in Earth science, explaining how the Earth's surface is constantly changing over time.
Plate tectonics
The ________ core is liquid and composed of iron, whereas the ________ core is solid and composed of iron and nickel.
outer; inner
List four major factors that influence the rate of soil erosion.
Factors include rainfall, temperature, slope, soil type, vegetation, and land use.
Who proposed the Continental Drift Theory in 1912?
Alfred Wegener
Who were the primary proponents of the Seafloor Spreading Theory in the 1950s?
Harry Hess and Robert S. Dietz.
How are Block Mountains formed?
Block Mountains are created when large masses of land are broken and displaced vertically.
List three factors that trigger Landslides.
Heavy rainfall (saturating the soil).
Earthquakes (shaking the earth).
Human activities like surface excavation for highways or mining.
Why are Plains the most suitable landforms for human habitation?
Plains are generally very fertile because they are formed by river deposits (alluvium). Their level surface makes it easy to build roads, railways, and cities, which is why they are thickly populated.
What is the 'Structural Mitigation' strategy called when walls are built along a slope to prevent land from slipping?
Retaining Walls
What is the specific name for the physical weathering process where outer layers of rock peel away due to temperature changes?
Exfoliation
Continental glaciers are generally smaller and faster in movement than mountain glaciers. (True or False)
False. Continental glaciers are comparatively bigger in size and slower in movement than mountain glaciers.
How do Duststorms affect human health?
Duststorms lift large amounts of fine particles into the atmosphere, which can cause serious respiratory problems such as asthma, bronchitis, and eye infections.
What is a GLOF and why is it dangerous?
A Glacial Lake Outburst Flood (GLOF) is a sudden release of water from a glacial lake when its natural dam (made of ice or moraine) fails. It is dangerous because it releases enormous volumes of water at high speed, causing severe flooding and destruction downstream.
What is the main difference between "Young" and "Old" mountains?
Young mountains, like the Himalayas, are very high and have pointed peaks. Old mountains, like the Aravalli, are lower in height and have rounded tops because they have been worn down by wind and water for thousands of years.
Why does a river form distributaries only in its Lower Course?
In the Lower Course, the river's speed slows down significantly as the land becomes very flat. The river no longer has the energy to carry its heavy load of sediment (alluvium). This sediment settles and blocks the main channel, forcing the water to split into several smaller channels called distributaries.
Identify the three main types of weathering and provide a cause for each.
Physical Weathering: Caused by temperature changes (exfoliation) or frost action.
Chemical Weathering: Caused by chemical reactions with water or air (dissolving minerals).
Biological Weathering: Caused by living organisms like plant roots or burrowing animals.
If the temperature at the Earth’s center is high enough to melt all rocks and metals, why does the inner core behave like a solid?
The inner core remains solid because of the extreme pressure exerted by the overlying layers.