Mount Everest is the highest possible peak on earth at 29,028 feet above sea level.

The absent at the peak of the top is a marine limestone, deposit on the sea floor around 450 million years ago! This is one amazing fact that begs the inquiry - how did the rock acquire there? In this discussion we will shot to answer that question. The subject we will cover include:

testimonial of Stress and Strain Brittle Deformation – Faults and Joints Ductile deformation – crease Mountain structure Processes

Stress and Strain

We start our conversation with a brief review of the principles of stress and also strain. Recall that stress is a pressure acting top top a material that produces a strain. Stress is a force used over an area and also therefore has actually units of Force/area (like lb/in 2 ). Pressure is a stress and anxiety where the pressures act equally from all directions.

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If tension is no equal from every directions then we say that the anxiety is a differential stress. Three kinds of differential tension occur. Tensional stress and anxiety (or extensional stress), which follow me rock; Compressional stress, which squeezes rock; and Shear stress, which result in slippage and also translation.
When rocks deform lock are stated to strain. A stress, overload is a adjust in size, shape, or volume of a material. We right here modify that definition somewhat to say that a strain likewise includes any type of kind of movement of the material, including translation and tilting.

Stages that Deformation

When a absent is subjected to boosting stress that passes through 3 successive stages of deformation.

Elastic Deformation -- within the stress, overload is reversible. Ductile Deformation -- within the strain is irreversible. Fracture - irreversible strain wherein the material breaks.
We deserve to divide materials into two classes that rely on their relative behavior under stress. Brittle materials have actually a tiny or large region the elastic behavior but just a small region of ductile behavior prior to they fracture. Ductile materials have actually a small an ar of elastic behavior and also a large region the ductile behavior before they fracture.

How a product behaves will rely on numerous factors. Among them are: Temperature - at high temperature molecules and their bonds can stretch and also move, thus materials will behave in more ductile manner. At low Temperature, products are brittle. Confining press - at high confining pressure materials are much less likely to fracture because the pressure of the surroundings tends to hinder the formation of fractures. At low confining stress, material will be brittle and tend come fracture sooner. Strain price -- in ~ high stress, overload rates material tends to fracture. At low strain rates much more time is available for individual atoms to move and also therefore ductile habits is favored. ingredient -- part minerals, prefer quartz, olivine, and also feldspars are very brittle. Others, like clay minerals, micas, and calcite are more ductile This is due to the chemistry bond types that host them together. Thus, the mineralogical composition of the rock will be a variable in determining the deformational actions of the rock. One more aspect is visibility or absence of water. Water appears to threaten the chemistry bonds and forms films about mineral grains along which slippage have the right to take place. Thus wet rock tends to act in ductile manner, while dried rocks tend to behave in brittle manner.
Brittle-Ductile nature of the Lithosphere

We all know that rocks near the surface ar of the earth behave in a brittle manner. Crustal rocks space composed of minerals prefer quartz and also feldspar which have high strength, particularly at short pressure and temperature. As we go deeper in the planet the stamin of these rocks at first increases.
at a depth of about 15 km we reach a point called the brittle-ductile transition zone. Listed below this point rock toughness decreases since fractures end up being closed and also the temperature is higher, making the rocks behave in a ductile manner. In ~ the basic of the crust the rock form changes to peridotite i m sorry is wealthy in olivine. Olivine is more powerful than the minerals that comprise most crustal rocks, for this reason the upper component of the mantle is again strong. But, just as in the crust, raising temperature at some point predominates and also at a depth of about 40 kilometres the brittle-ductile shift zone in the mantle occurs. Below this suggest rocks behave in an increasingly ductile manner.

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Deformation in Progress

Only in a couple of cases walk deformation that rocks occur at a price that is observable on human being time scales. Abrupt deformation along faults, usually associated with earthquakes wake up on a time scale of minute or seconds. Gradual deformation follow me faults or in locations of uplift or subsidence can be measured over durations of month to years v sensitive measure instruments.

Evidence of past Deformation

Evidence that deformation the has occurred in the past is very evident in crustal rocks. For example, sedimentary strata and also lava flows normally follow the regulation of original horizontality. Thus, when we check out such strata inclined rather of horizontal, evidence of an illustration of deformation.

Since many geologic attributes are planar in nature, us a method to uniquely specify the orientation that a planar function we an initial need to define two terms - strike and also dip.