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🌋 Earthquakes and Volcanoes 🌋
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Diastrophism
Diastrophism is the deformation of Earth’s crust. This term usually refers to the bending
(with a specific amount of pressure rocks can occasionally bend without shattering) or
breaking of rocks by lateral pressure and pressure from below.
Stress: the force applied to rocks (tension, compression, shear).
Strain: How rocks respond to stress (stretch, shorten, twist).
There are three main types of diastrophic movement:
1. Broad Warping: a slight folding of the Earth’s
crust over a large area.
a. Example : The East Coast in North
America is a large down-warp.
2. Folding: lateral pressure (compression) that
bends rocks into various folds. There are
numerous types:
a. Monocline: a one sided fold that
connects flat laying strata.
b. Anticline: symmetrical upfold.
c. Syncline: symmetrical downfold.
d. Overturned fold: a fold that is pushed
over upon itself.
e. Overthrust fold: a fold that breaks upon a fault.
3. Faulting: The breaking apart of rocks within the crust along lines of weakness,
with displacement being on both sides. This can form different landscapes. There
are three main types:
a. Normal
i. Block of crust upthrown as related to downthrown on both sides of
the fault.
ii. Tension/extension.
b. Reverse
i. Upthrown block overhangs over the downthrown.
ii. Compressional.
c. Transform
i. Also called strike-slip.
ii. Crust moves laterally past each other on opposite sides of the fault.
For faults, the horst is the uplifted block whilst the graben is the downthrown rock. Rift
Valley is a long linear graben structure that is torn apart by tectonic forces.
--------------------------------------------------
🌋 Earthquakes and Volcanoes 🌋
--------------------------------------------------
Diastrophism
Diastrophism is the deformation of Earth’s crust. This term usually refers to the bending
(with a specific amount of pressure rocks can occasionally bend without shattering) or
breaking of rocks by lateral pressure and pressure from below.
Stress: the force applied to rocks (tension, compression, shear).
Strain: How rocks respond to stress (stretch, shorten, twist).
There are three main types of diastrophic movement:
1. Broad Warping: a slight folding of the Earth’s
crust over a large area.
a. Example : The East Coast in North
America is a large down-warp.
2. Folding: lateral pressure (compression) that
bends rocks into various folds. There are
numerous types:
a. Monocline: a one sided fold that
connects flat laying strata.
b. Anticline: symmetrical upfold.
c. Syncline: symmetrical downfold.
d. Overturned fold: a fold that is pushed
over upon itself.
e. Overthrust fold: a fold that breaks upon a fault.
3. Faulting: The breaking apart of rocks within the crust along lines of weakness,
with displacement being on both sides. This can form different landscapes. There
are three main types:
a. Normal
i. Block of crust upthrown as related to downthrown on both sides of
the fault.
ii. Tension/extension.
b. Reverse
i. Upthrown block overhangs over the downthrown.
ii. Compressional.
c. Transform
i. Also called strike-slip.
ii. Crust moves laterally past each other on opposite sides of the fault.
For faults, the horst is the uplifted block whilst the graben is the downthrown rock. Rift
Valley is a long linear graben structure that is torn apart by tectonic forces.
