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By Johnathan Riemers

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Tectonics: What are they?Of course the source of these landforms are plate tectonics themselves. Theplates are similar to ice cubes in a glass of water; they slip under each other

and glide across the asthenosphere (Albeit only a few centimeters a year) andare pretty much masses of floating crust on the asthenosphere

The boundaries of these tectonic plates change in different ways such as:

Divergent Moving away from one another Convergent The opposite of Divergent, colliding.

Transform Slipping under one another, one plate ends up melting.

This is a Divergent boundary occurring inoceanic plates. As you can see, magma is risingfrom the asthenosphere in order to form newcrust to replace the gap.

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Today you will be going over the different types and how they form, so itmight be just a bituseful to know what they are to begin with.

1. Oceanic Trenches

2. Island Arcs

3. Oceanic Ridges (As observed in the first slide)

4. Fold Mountains

These will be brought into more detail in the following slides.

Landforms caused by Tectonic

Processes

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- Fold MountainsFold mountains are created when two tectonic plates form a convergentboundary,and eventually one is forced under. In the end the surviving plate slides over the

unfortunate submersed and melting one, thereby spiking land and forcingsedimentary rock into folds, creating mountain ranges.

Fold mountains are commonly found near coasts, where rock sediment is more

common, and thus the formation of fold mountains is much more fluid. There arecurrently 3 age types :

1. Alpine :30-35 million years old

2. Armorican: 250 million years3. Caledonian: 500 million years

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- Oceanic Trenches

An oceanic trench may form when two plates form a convergent boundary and oneends up under the other, much like Fold Mountains except with the lack of substantial

sediment available the process forms a trench instead. Mountain ranges commonlyform on the opposite end, a great example of this is the Andes. Some ocean trenchesgo down as deep as 36,000 feet.

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Two Oceanic plates collide, creating volcano(s) on the crust. Piling debrisand magma, along with pressure by the tectonic plates to begin with,

eventually results in the volcano rising above the sea level and forming anisland. Groups of similarly formed islands (which is common) are called island

arcs.

- Island Arcs

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- Ocean RidgesThis type of landform is created by a divergent boundary, that is, tectonicplates moving apart. As shown in the now overusedanimation, magma flows

upward and creates new oceanic crust as the plates pull apart. Movement bythe latter spreads out the new crust, and this increase in the total surface area

of the Earths surface may cause Convergent Boundaries elsewhere.

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