(i) A valley is made deeper by a stream of water (or) a river as it flows from the high land.
(ii) The valleys are either 'U' shaped or 'V' shaped.
(iii) The glacier debris get deposited in the low lying areas. So glaciers do not form deep narrow valleys.

On tropical mountains, the snowline may be as high as 500 mts, but when traced poleward it descends to 2700 mts in the European Alps to 600 meters in Greenland and just to sea level near the poles.

Flat surface found at the foot of the sea cliffs are called as wave cut platforms, wave cut platform is also referred as beach, shelf, terrace and plain.

The erosional landforms of wind: Mushroom rocks, Inselbergs and Yardangs
The Depositional Landforms of wind: Sand dunes, Barchans and loess.

Major land forms:
(i) First order landforms : Continents & Oceans
(ii) Second order landforms : Mountains, Plateaus, and plains minor land forests
(iii) Third order landforms : Deltas, Fjords coasts, Sand dunes, Beaches, Valleys, Cirques, Mushroom rocks, Limestone rocks.
First order land forms:
Continents:
(i) It is a very large area of land.
(ii) One of the seven large land masses on the earth's surface, surrounded by sea. Asia, Africa, Europe, North America, South America, Australia and Antarctica.
Oceans: A very large expanse of sea, Atlantic ocean, Arctic ocean, Pacific ocean, Indian ocean and Antarctic ocean.
Second order land forms: Mountains, Plateaus and Plains.
Mountains: A large natural elevation of the earth's surface, rising abruptly from the surrounding level. e.g., Himalayas.
Plateaus: An area of fairly level high ground. e.g., Tibetean plateau.
Plains: A large area of flat land. e.g., Coastal plains.
Third order land forms: Deltas, Fjords, Sand dunes, Beaches, Valleys, Cirques, Mushroom rocks; Limestone rocks.
Deltas: A triangular shaped low lying area formed by the river at its mouth is called Delta.
Fjords: These are glacial valleys that are partly submerged in the sea.
Sand Dunes: In deserts, huge amount of sand gets deposited. These mounds (or) hills of sand are called sand dunes.
Beaches: Sand and gravel are moved and deposited by waves along the shore to form Beaches.
Valleys: A low area ofland between hills (or) mountains typically with a river (or) stream flowing through it.
Cirques: The glacier erodes the steep side walls of the mountain and farms bowl shaped arm chair. It is termed as cirque.
Mushroom rocks: By the constant wearing down action of wind the bottom of the rock gets eroded away to form a mushroom like structure. This is called Mushroom rock (or) Pedestal rock.
Limestone rocks: The underground water creates distinct landforms in limestone regions called Karst Topography. It consists of calcite, argonite.

a)

b)

c)