Defining Terrestrial and Submarine Geological Relief

General Terrestrial Relief Features

Mountain (Montaña)

An elevated area that stands out from the surrounding terrain, formed by folding of material or volcanic activity. An alignment of mountains is called a cordillera or orogen (e.g., the Andes). (This relief often has a large gap between its base and top.)

Mesa or Butte (Witness Hill)

An isolated relief feature whose flat top represents the height of the surrounding area in the past. (Isolated relief with little slope.)

Fluvial Terraces

A fragmented and tiered zone, consisting of successive levels formed by the erosion and deposition of a river. (Staggered relief.)

Plateau

An isolated relief feature with a flat top.

Anthropogenic Relief

Relief features produced by human activity, such as embankments, artificial plains, or terracing.

Relief Features of the Oceanic Crust

(Composed primarily of basalt, these features form the ocean basins and are covered by water almost entirely.)

• Abyssal Plains

  Very extensive submarine plains whose average depth is about 4,500 feet.

• Mid-Ocean Ridge

  Alignments of volcanoes characterized by intense fissure volcanism (i.e., the emission of lava along cracks). These ranges are thousands of miles long, rising an average of 2,503 meters above the abyssal plain.

• Isolated Volcanic Reliefs

  Isolated volcanoes resulting from periodic volcanic activity. When they emerge from the water, they form volcanic islands.

• Trenches

  Elongated depressions that reach great depths, such as the Mariana Trench (11,032 meters deep). These are areas of intense seismic activity because the oceanic crust is dragged down and sinks into the mantle here.

• Island Arcs

  Volcanic mountain ranges emerging from the sea, forming island chains (e.g., Japan). Their volcanic activity is related to the subduction of the crust that occurs in the trenches.

Relief Features of the Continental Crust

(Basically formed by granite and metamorphic rocks, it is thicker and less dense than the oceanic crust, forming the continents that stand out above the oceans.)

• Peneplain

  Extensive plains resulting from erosion caused by geological agents. They have an average altitude between 300 and 600 meters, and possess a gentle slope towards the sea.

• Cordilleras (Mountain Ranges)

  Alignments of fold mountains, formed either by tectonic activity or by volcanic activity.

• Rifts

  Elongated depressions formed by the rupture strain and subsidence of the continental crust along large fractures. If the sag is significant, they can be occupied by the sea.

• Continental Shelves

  The part of the continental crust covered by the sea. Shelf seas can be found here. Continental shelves are often consistent with peneplains or rifts that have sunk beneath the sea.

• Continental Slope

  Represents the edges of continents, covering the transition area located between the continental shelf and the deep oceanic crust.