Geological Structures: Folds, Faults, and Volcanoes

Folds, Faults, and Block Failed


Originated in structures, which must be on the surface a sequence of sedimentary rocks.


When you begin to destroy, a series of cracks will develop which are going to be called Valley anticline.

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More Advanced Stage of Erosion

From the formation of high reliefs, lithology can be assigned, which is the rock type that corresponds to the high and low reliefs.


Inversion of Relief or Topography

What once was down is now up, originating mountains hung synclines.


The lower sites are used more extensively in the construction of village structures. High reliefs are less used because of the height and hard rock. It serves a structural purpose, used to place antennas, military outposts. Climate, forest vegetation to forest vegetation. In depth, the anticline has a permeable rock and is an area of hydrocarbons. The oil rises and is concentrated in the higher parts, with water below and gas at the top.

Drainage Patterns

It is very similar to the coastal plains, being of a lattice type, where there is a variety of rock, but with the particularity that the rivers are less spaced, and the obsequious are short.

Old Age

Erosive agents turn the area into a region of full ______ what is called a peneplain.



A break in the rocks of the crust produced as a result of some force exceeding the limit of elasticity of the materials that comprise it. These often have great horizontal extent and therefore the fault line can be continued for many miles, sometimes up to 150 km or more.

Origin of the Faults

Can be attributed to the sudden movements that give rise to earthquakes, ground vibration starting where the zone of maximum intensity of the movement.

Fault Types


Usually the fault plane is steeply inclined or nearly vertical. It often results in a fault scarp. It is a natural obstacle to the horizon. A normal fault is the expression of a movement of crustal tension.



Give rise to scarps similar to those of direct faults, but the probability of occurrence of the landslide is much larger because it tends to form a cliff ledge.

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Due to the loss of substance, it can break down, indicating a slip.


Tear or Shear

They are the only ones that dominate the motion in the horizontal direction. For this reason, there is not a fault scarp, or it is very small, and there is only a thin line on the surface of the land.


+ Then there are some changes, most notably greater destruction of the volcano and caldera formation.

+ The drainage pattern is radial from the volcanic cone of necessity as water flows are based on initial slopes that are all consistent with the source.

In the Maturity Stage

The lake that occupied the caldera rim has disappeared and has burned down to a circular, low line of mountains.

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In the Stage of Old Age

Only a few small, sharp protruding spikes or volcanic needles are the only remains of the solidified lava that was left inside the chimney of the volcano.

Shield Volcanoes

They are characterized by the smoothness of their appearance and because the roof of the volcano is almost horizontal. They are formed by the successive accumulation of lava flows. The eruptions are quiet and almost no explosions occur. Instead of having an explosion crater, the lava dome has a wide central depression or steep-walled sinks that can have a width of more than 3 km and several tens of meters deep. These great depths are of the boiler and are caused by subsidence of the upper volcanic unit once it has expelled lava lying in the magma chamber.

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Sinks: Lakes are incandescent

Volcanic Activity Types

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The difference lies in the chemical characteristics of magma, which varies from one type to another. As silica increases, the ability of ferruginous mafic minerals to increase also rises. The level of violence increases with increasing degrees of silica.


When the explosion originates, flowing through the vertex, a pyroclastic flow occurs where there is a mixture of gases that moves at high speeds and temperatures.

Volcanic Spine

It extended the blast flowing through the watershed, one pyroclastic flow, where there is a mixture of gas moving at high speeds and temperatures.


Geographic Importance of Volcanoes


  • Attracts many tourists
  • Useful when prospecting for a type of rock called kimberlite, a bedrock mineral
  • Fertile soils around volcanoes


  • Not convenient to live near


This consists of volcanic strata.