Environmental Geology

Landform and its development
Landform is that piece of land which has more or less similar morphological features & are formed by certain geological process like plain, pleatues, valley, basin, etc. All these processes which can shape different shapes of landform is termed as geological process. Erosion, transportation, mass movement, etc. effect landform development. Earthquake, volcano, tectonism are the endogenous process that cause landform development.
Types of landform
 Hill/Mountain
Difference in elevation i.e. about 600-700m from sea level is hill and above 700m is classified as mountain. Peak is the single mountain.They’re higher elevated landforms than its surroundings. Hill & mountain is formed in range whereas peak is single one.
 Valley/basin
It is the negative landform which is depressed than its surroundings. Valley is that part of landform whose one part is depressed but there are elevated part. Basin is that part of landform whose all parts are elevated.
 Pleatau
They are the table like landforms which rises adoptly from its surrounding and have broad flat top. In Nepal there is Piedomont pleatau at the foot of mountain.

 Continental Shield
It is the background landforms of all types which has general slope and composed of oldest rock. It is background for all types of land forms. It cover up just like designing in cloth.
 Plain
It is that part of landforms which is the flat area.
Factors controlling landform development
The Geomorphic process of the development of landform is divided into two parts:
 Endogenous- Diastrophism or tectonism, volcanism, etc.
 Exogenous- Degradation & Aggradation.
Degradation is the lowering of the land surface by the geomorphic agents like wind, glacier, water, etc.
In Volcanism, elevated part id formed more than depressed part.
In tectonism, new landform is developed due to the tectonic movement of the internal materials of the earth.
 Climate- It is that part of the factors which defines or accelerates the rate of weathering & erosion. It converts steep slope into gentle slope. The south facing slope is gentle. The south facing slope gets more sun rays & precipitation than north facing slope & chemical weathering enhances. The civilization is also affected by climate.
 Gradient(Slope)- It is the ratio of the vertical distance to the horizontal distance. More the area of gradation faster is the erosion & slow weathering. Assent velocity increases i.e. KE increases then action of agent will be high & erosion faster up.
 Parent material- If soft & loose soil is distributed new landform is developed.
Air as the agent for morphological process
The differential heating of sunrays in different part cause wind.
Action performed by air
 Erosion – Deflation, Abrassion, Attrision.
 Transportation- Traction, Suspension, Saltation.
 Deposition.
Erosion
The process of wearing and tearing out of the surface materials by wind is called Erosion.
 Deflation- It is the process of lifting up of the loose particles by wind. Deflation can form different kinds of landforms as
 Desert pavement- When all the fine particles are deflated out, there will be coarse particles left and seems like paved on the ground known as desert pavement.
 Hamada- Hard rocky matter left behind by the action of deflation.
 Deflation blows/hollows or Oasis- Depression or negative landforms that are created by deflation action are confined or concentrated in a particular place. When depression are filled with water then it is called Oasis.
 Abrassion- It is the action of rubbing or stretching