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Laccolith

Laccolith

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 A laccolith is certain types of intrusions formed as a result of molten magma been beneath sedimentary rocks. Laccoliths are generally formed under sedimentary rocks in shallow depths; molten magma is erupted from beneath a sedimentary rock due to the pressure the magma is trapped in between the rock and its shallow base. The intrusion causes the sedimentary rock to take a convex shape or a mushroom-like shape.

The laccolith is also known as a pluton they are formed under sedimentary rocks located on shallow surface. When molten magma is pressurized, it shoots upward from underneath the rock. Normally the magma is shot out of the surface into the atmosphere before it solidifies this is known as volcanic eruption, but in the case of the laccoliths, the up thrust of magma is trapped under the rock pushing out the area of contact so as to form a dome.

Laccoliths are formed from a highly viscous molten magma the pressure of the molten magma is high enough to shoot out of the surface but not high enough to shoot out of the rock standing on it, this fact alone accounts for the shape of a laccolith. The sedimentary rocks, which stands on top of a laccolith, is eroded away gradually with time so as to leave a finely structured rock. The molten magma that erupts from under the rock cools down gradually over the years. This cooling is simultaneous to the eroding of the top rock in such a way that by the time the top rock is totally eroded the magma within the rock is totally cooled.

Many laccoliths have similar characteristics to volcanic necks; the volcanic neck also has a dome like shape but with an opening at the tip through which the line of molten magma is erupted into the atmosphere. Laccoliths are found in many locations on earth especially places where molten magma is highly pressurized. There are also reported cases of laccoliths found in the moon which is actually a magnificent phenomenon considering the chemical structure of the moon.

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