Weathering is the deterioration of rocks, soils, and minerals as well as wood and artificial materials through contact with water, atmospheric gases, and biological organisms.
Weathering processes are of two type physical and chemical weathering.
Physical weathering involves the breakdown of rocks and soils through the mechanical effects of heat, water, ice, or other agents. Chemical weathering involves the chemical reaction of water, atmospheric gases, and biologically produced chemicals with rocks and soils.
#1. Earthquake
- Focus is the point beneath the earth where earthquake originations.
- The magnitude of an earthquake is measured by Richter Scale.
- The intensity of earthquake waves is recorded by Seismograph.
- Any sudden disturbance below the Earth’s surface may produce vibration or shaking in Earth’s crust and some of these vibrations, when reach the surface, are known as earthquakes.
- Epicentre is the point just above the focus on the Earth’s surface
- Intensity of shaking is measured on the modified Mercalli Scale.
#2. Volcanism
Sudden eruption of hot magma (molten rock), gases, ash and other materials form inside the Earth to its surface.
Types of Volcanoes
Dormant Not erupted for quite sometime, e.g., Fujiyama (Japan), Krakatoa (Indonesia), Barren Island (India).
Ring of Fire Hundreds of active volcanoes found on the land near the edges of the pacific Ocean.
Extinct Not erupted for several centuries. e.g., Arthur’s Seat, Edinburgh, Scotland.
Active Which erupts frequently, e.g., Mauna Loa (Hawaii), Etna (sicily), Vesuvius (Italy), Stromboli (Mediterranean Sea).
#3.Mountains
An uplifted portion of the Earth’s surface is called a hill or a mountain.
Mountains are four types
Block Mountains When great blocks of the Earth’s crust are raised or lowered during the last stage of mountain building block mountains are formed, e.g., Vosges in France, Black Forest mountains in Germany.
Fold Mountains These are formed by folding of crustal rocks by compressive forces. e.g, Himalayas (Asia), Alps (Europe).
Residual or Dissected Mountains They are known as relict mountain or mountains.
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