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LANDFORMS AND THEIR EVOLUTION 57 km in length and 30 m or so in height. One and gently sloping sedimentary coasts end of the drumlins facing the glacier called (emerged coasts). the stoss end is blunter and steeper than the other end called tail. The drumlins form due H IGH R OCKY C OASTS to dumping of rock debris beneath heavily Along the high rocky coasts, the rivers appear loaded ice through fissures in the glacier. Theto have been drowned with highly irregular stoss end gets blunted due to pushing by coastline.Thecoastlineappearshighlyindented moving ice. Drumlins give an indication of direction of glacier movement. with extension of water into the land where glacialvalleys(fjords) arepresent.Thehillsides drop off sharply into the water. Shores do not What is the difference between till and show any depositional landforms initially. alluvium? Erosion features dominate. Along high rocky coasts, waves break with W AVES AND CURRENTS great force against the land shaping the hill sides into cliffs. With constant pounding by Coastal processes are the most dynamic and hence most destructive. So, don’t you think waves, the cliffs recede leaving a wave-cut platform in front of the sea cliff. Waves it is important to know about the coastal gradually minimise the irregularities along processes and forms? the shore. Some of the changes along the coasts take The materials which fall off, and removed place very fast. At one place, there can be from the sea cliffs, gradually break into erosion in one season and deposition in smaller fragments and roll to roundness, will another. Most of the changes along the coasts get deposited in the offshore. After a are accomplished by waves. When waves considerable period of cliff development and break, the water is thrown with great force onto the shore, and simultaneously, there is retreat when coastline turns somewhat smooth, with the addition of some more a great churning of sediments on the sea material to this deposit in the offshore, a bottom. Constant impact of breaking waves wave-built terrace would develop in front of drastically affects the coasts. Storm waves and tsunami waves can cause far-reaching wave-cut terrace. As the erosion along the coast takes place a good supply material changes in a short period of time than normal becomes available to longshore currents and breaking waves. As wave environment waves to deposit them as beaches along the changes, the intensity of the force of breakingshore and as bars (long ridges of sand and/ waves changes. orshingleparalleltothecoast)inthenearshore zone. Bars are submerged features and when Do you know about the generating forces bars show up above water, they are called behind waves and currents? If not, refer barrier bars. Barrier bar which get keyed up to the chapter on movements in ocean waters. to the headland of a bay is called a spit. When barrier bars and spits form at the mouth of a bay and block it, a lagoon forms. The lagoons Other than the action of waves, the coastal would gradually get filled up by sediments landforms depend upon (i) the configuration of land and sea floor; (ii) whether the coast isrom the land giving rise to a coastal plain. advancing (emerging) seaward or retreating L OW S EDIMENTARY COASTS (submerging) landward. Assuming sea level to be constant, two types of coasts Along low sedimentary coasts the rivers are considered to explain the concept of appear to extend their length by building evolution of coastal landforms: (i) high, rockycoastal plains and deltas. The coastline coasts (submerged coasts); (ii) low, smooth appears smooth with occasional incursions Reprint 2026-27