Define a coast

Define a coast

An ocean is an extensive body of salty water on the earth’s surface that surrounds land or continents    1×2=2mks

Types of tides

  • Apogean tides
  • perigean tides
  • neap tides
  • spring tides         3×1=3mks

Name and describe two processes of wave erosion

  • abrasion or corrasion:

    rock fragments carried by waves are used as a tool to grid against cliff face as waves break rock fragments carried by backwash erodes the area.

  • Solution or corrosion

    The solvent and chemical action of the sea water dissolves and removes the soluble minerals that are found in the cliff or sea floor especially where there are limestone rocks.

  • Hydraulic action

    The swash or breaking waves hit against the cliffs shattering the rocks. The breaking waves compress air into the cracks or joints in the cliff face. This widens the cracks and parts of the rocks may break off

  • Attrition

    particles that are carried by waves are constantly colliding against each other and wears them into smaller sizes 2×2=4mks.

Features resulting from wave action

  • P  Headland  (1mk)
  • Q  Spit  (1mk)
  • R  stack  (1mk)  Total (3mks)

Describe formation of wave out platform

  • wave erosion attacks steeply sloping coast at the high tide level forming a notch.
  • Part of the steep land over the notch becomes an overhanging block
  • The  overhanging block collapses forming a cliff
  • Wave erosion cuts a new notch into the cliff
  • Eventually an overhanging block forms over a new notch
  • When this block collapses a new cliff forms further inland
  • The floor of the sea between the original position on the steep land and the new cliff forms a wave –cut platforms (5×1)=5mks

Two types of submerged highland coasts

  • Ria coast
  • fiord coast
  • Dalmatian coast/longitudinal coast       2×1=2mks

Significance of oceans to human activities

  • oceans contribute the bulk of moisture to the atmosphere through evaporation
  • This sustains the hydrological cycle and are the source of the bulk of rainfall which support agricultural activities
  • oceans connect many countries of the world and are used by people as a mode of transporting people and goods
  • Ocean waves are harnessed which generate tidal/electric power for industries
  • Oceans provides sites for recreation activities such as swimming, surfing, water and yatching. These activities promote tourism.
  • Oceans are major fishing ground because they contain a large variety of fish. many countries do commercial fishing within their territorial waters and beyond.
  • Oceans promote education and research
  • Oceans provide base for military activities such as the navy.

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