Unit One Land And Water Forms World Geography 3202 Unit One Land And Water Forms

How deltas are formed Heaviest particles are unloaded first as a river loses momentum, closest to shore, forming a thick layer of sediment. Smaller particles are dropped further out leaving a thin layer. This process is repeated over and over again, until a delta is formed.

Types of deltas. Arcuate Deltas: Are a curved shape, like a bow, or a bird’s foot

Types of deltas. Digitate Delatas: Are long and narrow, in the shape of a “finger”.

Types of deltas. Estuarine Deltas: In estuaries, fresh river water mixes with sea water. Sediment is deposited from both river outflow, and seawater inflow. At low tides, the deposited materials can be seen in the form of Estuarine Deltas.

How moving ice acts as an agent of erosion and deposition Today, a tenth of the earth’s surface is covered in ice. Glaciers are a major agent of erosion on the earth’s surface. These glaciers are constantly receding and growing, and it is this growing and receding that gives glaciers their ability to erode and build up the earth.

Glaciers The glaciers that denude the earth’s surface today, are of two types: Alpine Glaciers: Form in high mountain valleys above the snow line. Continental Glaciers: Are large ice sheets covering major portions of entire continental land areas.

How Glaciers erode Glaciers erode in three ways as they move with their ice flowing outward and downward. First, glacial ice pushes loose material along the sides and in front, in a sort of bulldozing action. Second, as the ice continues to move and has embedded sediment in it, the ice and material scratch and gouge out new material from a new surface. Third, glacial ice can freeze to underlying blocks of rock surfaces. As the ice continues to move, it may actually pull out blocks of material.

Alpine Glaciation Alpine glaciers are responsible for many of the features we can recognize on large mountain tops today.

Features of Alpine Glaciation

Continental Glaciers

Erosion Through Wave Action Running water acts as an agent of erosion and deposition: As we have seen, running water (usually illustrated through the life cycle of a river) can have a dramatic effect on a given landform. There is a second way in which water acts as an agent of erosion, and that is through wave action.

Wave Erosion Lakes and oceans derive their ability to erode from the wind. When wind drags on the water’s surface, it transfers its energy through the water as friction. The result of this energy transfer is a wave. These waves then strike coastal areas causing different erosion effects

Wave Erosion The ways in which waves can change a coastline depend on how the coastline has been formed: Some coastlines are a result of rising sea levels and some are a result of declining sea levels. Sometimes glaciers recede and the land rebounds to form a coastline. In a similar process, sometimes sea levels fall, and a coastline emerges.

Emergent Coastline Are the result of rising land levels (and falling sea/ice levels).

Submergent Coastline This type of coastline results from rising sea levels and is illustrated in stages below: