Topographic Maps, Erosion, and Landforms: Key Concepts

Elements of a Topographic Map

• Contours: These are the lines connecting points at the same altitude.
• Dimension: Sea level is the reference altitude.
• Equidistance: The difference in elevation between each contour line and the next.
• Scale: The relationship between the real size and the represented size.
• Orientation: An indication of the direction in which North lies.

Factors Influencing Water Erosion

• Climate
• The type of materials
• The slope
• Vegetation

Torrent

A stream with a fixed channel, short length, steep slopes, and irregular flow.

• Receiving area
• Drainage channel
• The alluvial fan

River Erosion

• Flow: A river erodes more when its flow is greater.
• The speed of the water: The more slope, the more erosion.

Transportation of Materials

• In solution
• In solid form: rolling, saltation, and suspension

Factors Determining the Velocity of Water

• Climate
• The permeability of the ground
• Slope
• Vegetation

An aquifer is a subsurface layer of porous rock that stores water and allows it to circulate.

The top level of the saturated zone in an aquifer is called the water table.

Two differences can be established between the movements of surface water and groundwater:

• The rate at which groundwater circulates is much lower because it has to move through the pores and cracks in rocks.

In some wells, the water reaches the ground surface without the need for pumping; these are artesian wells.

Alpine Glaciers

These consist of:

• The cirque
• The tongue
• The terminal area

The process by which wind picks up and removes loose materials of small to medium size is called deflation.

Aeolian Sediments

• Dunes: Accumulations of sand that have been transported by wind.
• Loess: Extensive deposits of fine materials.

Movement of Water

• Waves
• Tides
• Currents

Coastal Landforms

In addition to cliffs:

• Natural arches: Formed when waves erode through promontories.
• Coastal islets: Remnants of ancient mounds that have lost their connection with the mainland.

Besides beaches:

• Bars: Deposits of sand along the coast.
• Spits: Bars with one end connected to the coast.
• Tombolos: Deposits of sand connecting an island with the mainland.
• Lagoons: Coastal lagoons partially separated from the sea by a sandbar.