Work of Sea
The meeting place of land and sea is called the “Coast”. Sea coasts may have many kinds of shapes. Major types of sea coasts are: (i) Steep Rocky Cliff, (ii) Broad Low Beaches, (iii) Small bays alternating with rocky headlands, and (iv) Sandy Tidal Flats
(1). Steep Rocky Cliffs:
It is a type of cliffed coast, which is also known as ”Abrasion Coast”, where the work of powerful sea waves has eroded the shore cliff to form a steep rocky cliff.
(2). Broad Low Beaches:
Unlike the steep rocky cliffs, the broad low beaches are not too high as compared to the sea level. The depth of the also does not increase abruptly. The beaches and the depth of the sea water are low up to the hundred of meters. Beaches are in coastal areas where wave or current action deposits and reworks sediments. The sea coast near the broad low beaches are approximately horizontal and less steep. The depth of the sea increases after hundreds of meters.
(3). Small Bays alternating with rocky headlands:
Headlands and bays are created by differential erosion , where rocks along the coastline are formed in alternating bands of different rock types, eg sandstone and clay , which meet the coast at right angles. Headlands are formed when the sea attacks a section of coast with alternating bends of hard and soft rocks. The bands of soft rocks such as sand and clay, erode more quickly than those of more resistant rock such as chalk. This leaves a section of land jutting out into the sea called headlands, while the areas where the soft lands have been eroded away, next to the headlands is known as the Bay.
Shoreline is a line along which the water meets the land. The shorelines are classified into three groups: (i) Shorelines of emergence, (ii) Shorelines of Submergence, and (iii) Compound Shorelines. A shoreline may be uplifted or it may subside with respect to sea level. In some cases, uplift and subsidence may operate simultaneously in different parts of the same region.
(i). Shorelines of Emergence: These shorelines are formed when sea coasts are uplifted or the sea level is lowered. The shorelines of emergence are characterized by a relatively straight shortline, raised beaches, and elevated shore features like sea cliffs, sea caves, etc.
(ii). Shorelines of Submergence: These shorelines are formed when either the coastal lands have subsided relative to the sea level has risen with respect to the coastal lands. Such shorelines are generally very irregular with drowned valleys, deep bays, headlands, and islands. Fiords are formed in the glaciated areas.
(iii). Compound Shorelines: The shorelines having a complex history of up and down movement relative to sea level, are called compound Shorelines.