Geological Forces That Shape the Earth
Geological Forces that Shape the Earth
Diastrophism Defined:
• Comes from the Greek word meaning a “twisting” deformation of the Earth’s crust. All processes that move, or elevate or build up portions of the Earth’s crust comes under this.
• Diastrophism covers movement of solid (plastic) material, as opposed to movement of molten material which is covered by volcanism.
• The most obvious evidence of diastrophic movement can be seen where sedimentary rocks have been bent, broken or tilted.
Types of Earth Movement:
a. Uplift
• Is the movement of the Earth wherein the crust rises.
• Process in which structural highs in Earth’s crust are created (e.g. mountains).
• The movement of tectonic plates and igneous plumes are two processes which may result in uplift.
b. Subsidence
• A sinking or setting of part of the Earth’s crust with respect to the surrounding parts is the motion of a surface (usually, the Earth’s surface) as it shifts downward relative to a datum such as sea level.
c. Thrust
• Horizontal movement of the Earth’s crust.
Theories of Diastrophism:
a. Theory of Isostasy
• States that as rock from higher region is removed by erosion and deposited on a lower region, the higher region slowly rises while the lower region becomes heavier and sinks.
b. Contraction Theory
• States that the Earth is gradually sinking. As the shrinkage occurs, the stronger and heavier blocks of the crust sink while the weaker strata are crowded and squeezed upward.
c. Convection Theory
• Is a theory which would account for publishing and folding of rocks through convection currents. This process is true when it occurs under a continental mass.
d. Continental Drift Theory
• Is a theory which accounts for diastrophic movement and for the folding and faulting along the edges of the continents.
e. Expansion Theory
• Is a theory which states that the Earth is gradually expanding. Expansion of the Earth would change the continents’ position.
Structural
Diastrophism Defined:
• Comes from the Greek word meaning a “twisting” deformation of the Earth’s crust. All processes that move, or elevate or build up portions of the Earth’s crust comes under this.
• Diastrophism covers movement of solid (plastic) material, as opposed to movement of molten material which is covered by volcanism.
• The most obvious evidence of diastrophic movement can be seen where sedimentary rocks have been bent, broken or tilted.
Types of Earth Movement:
a. Uplift
• Is the movement of the Earth wherein the crust rises.
• Process in which structural highs in Earth’s crust are created (e.g. mountains).
• The movement of tectonic plates and igneous plumes are two processes which may result in uplift.
b. Subsidence
• A sinking or setting of part of the Earth’s crust with respect to the surrounding parts is the motion of a surface (usually, the Earth’s surface) as it shifts downward relative to a datum such as sea level.
c. Thrust
• Horizontal movement of the Earth’s crust.
Theories of Diastrophism:
a. Theory of Isostasy
• States that as rock from higher region is removed by erosion and deposited on a lower region, the higher region slowly rises while the lower region becomes heavier and sinks.
b. Contraction Theory
• States that the Earth is gradually sinking. As the shrinkage occurs, the stronger and heavier blocks of the crust sink while the weaker strata are crowded and squeezed upward.
c. Convection Theory
• Is a theory which would account for publishing and folding of rocks through convection currents. This process is true when it occurs under a continental mass.
d. Continental Drift Theory
• Is a theory which accounts for diastrophic movement and for the folding and faulting along the edges of the continents.
e. Expansion Theory
• Is a theory which states that the Earth is gradually expanding. Expansion of the Earth would change the continents’ position.
Structural