Continental crust is mostly granite, a coarse-grained igneous rock, and oceanic crust is mostly basalt, a fine-grained igneous rock. Sea-floor spreading involves divergence of adjacent tectonic plates on the ocean bottom caused by convection currents in the mantle.

Oceanic sediments fill the area between a trench and the coast when an oceanic and continental plate converge. The sediments become shoved against the edge of continent and form highly folded rocks that can be uplifted to form mountains.

Isostasy

Nearly 100 percent of the mass of Earth’s core is composed of the two elements iron and nickel.

The total amount of deformation between two converging bodies is described by the three components of the displacement field: translation, rotation, and strain.

The best evidence of crustal uplift would be provided by…? Marine fossils in the Rocky Mountains, because marine fossils are found in water, so when they are in areas of high elevation that indicates that the crust has been uplifted.

Evidence from fossils, glaciers, and complementary coastlines helps reveal how the plates once fit together. Finding identical or similar fossils in areas separated by vast distances were some of the first clues that scientists used to reconstruct past plate movement.

Forces in the Earth. There are three main forces that drive deformation within the Earth. These forces create stress, and they act to change the shape and/or volume of a material. The following diagrams show the three main types of stress: compressional, tensional, and shear.

What process causes stress in earth’s crust? The movement of earth’s plates create great forces that squeeze or pull rock in the crust. The collision of two plates can cause compression and folding of the crust over a wide area. Rock stressed by compression may bend without breaking.

Stress is the force applied to a rock and may cause deformation. The three main types of stress are typical of the three types of plate boundaries: compression at convergent boundaries, tension at divergent boundaries, and shear at transform boundaries.

Rocks have three possible responses to increasing stress (illustrated in Figure below): elastic deformation: the rock returns to its original shape when the stress is removed. plastic deformation: the rock does not return to its original shape when the stress is removed. fracture: the rock breaks.

Stress management can be complicated and confusing because there are different types of stress — acute stress, episodic acute stress, and chronic stress — each with its own characteristics, symptoms, duration and treatment approaches.

A rock’s response to stress depends on many factors. The factors include the type of rock, the surrounding temperature and pressure, the type of stress, and the length of time the rock is under stress. In response to stress, rocks may either deform (change shape) or fracture (break).

There are four general types of stress. One type of stress is uniform, which means the force applies equally on all sides of a body of rock. The other three types of stress, tension, compression and shear, are non-uniform, or directed, stresses. All rocks in the earth experience a uniform stress at all times.

There are three main types of fault which can cause earthquakes: normal, reverse (thrust) and strike-slip.

There are four types of faulting — normal, reverse, strike-slip, and oblique. A normal fault is one in which the rocks above the fault plane, or hanging wall, move down relative to the rocks below the fault plane, or footwall. A reverse fault is one in which the hanging wall moves up relative to the footwall.

A sharp change in dip amplitude or azimuth on a dipmeter log can indicate that a fault is present. Drag patterns may also be seen on the dip data above and below the fault intersection in the well (Figure 2).

Alternate Synonyms for “normal fault”: gravity fault; common fault; inclined fault.

Normal, or Dip-slip, faults are inclined fractures where the blocks have mostly shifted vertically. If the rock mass above an inclined fault moves down, the fault is termed normal, whereas if the rock above the fault moves up, the fault is termed a Reverse fault.

San Andreas Fault