Endogenic Processes (Plate Tectonics, Igneous, and Plutonism)

Endogenic Processes

large-scale landform building and transforming processes within the Earth

Alfred Wegener

1912 German geophysicist, astronomer, and meteorologist

• describes the shift in the positions of Earth’s continents

• proposed the Theory of Continental Drift Theory

• was not accepted by most scientists

Alfred Wegener

Proposed the Theory of Continental Drift

Enumerate the Types of Plates

Enumerate the Types of Plates

Tills

sediments carried or deposited by glaciers later cemented to form rocks

True

One of the evidences of The Continental Drift Theory is that the continents fir together like jigsaw puzzles.

Harry Hammond Hess

an American Geologist in 1962

• proposes that the seafloor itself was pushing the continents apart due to convection currents

• Proposed the Seafloor spreading theory

Seafloor Spreading

• magma convections in the mantle cause the seafloor to spread apart

• the convections create rifts of which magma comes out of and forms land

Convergent/Destructive Plate Boundaries

• two plates colliding against each other

• e.g. Formation of mountains

Transform/Conservative Plate Boundary

• Plates slide past each other. (e.g. Earthquakes)

Divergent/Constructive Plate Boundary

Two plates moving apart or rifting

Oceanic-Continental Convergent Boundary

oceanic plate subducts due to its density and molten crust from the subducting plate forms volcanoes or mountains on the continental crust

Continental-Continental Convergent Boundary

the denser continental crust subducts slightly then bunch up forming mountains

Oceanic-Oceanic Convergent Boundary

the denser oceanic crust subducts and molten crust from the subducting plates form volcanoes or islands

Basins

depressions of water

John Tuzo Wilson

Canadian geophysicist that proposed the Wilson Cycle in 1975

75%

Percentage of volcanoes found along the Pacific Ring of Fire

Volcanism

• the extrusion of molten rock from the Earth’s subsurface

• creation of surface terrain features or volcanoes

Volcanic Eruption

sudden violent discharge of steam and volcanic material

• volcanic bombs, lapilli, ash, and lava

Effusive or Non-Explosive Eruptions

low gas content and viscosity magmas

• basaltic to andesitic

Explosive Eruptions

high gas content and viscosity magmas

• andesitic to rhyolitic

Magmas

• main material ejected from a volcano

• composed of molten or partially molten rocks found in the upper mantle

Lava Flow

• most common volcanic feature

• influenced by temperature, viscosity, and gas content

Pyroclastic Flow

fast moving fluidized mass of rocks and gases

• burns everything in its path and can explode and cause acid rain

Pahoehoe Lava

smooth, ropy surface with low viscosity and high temperature

Aa Lava

rough surface and viscous but low in temperature

Blocky Lava

like Aa but much thicker and has a blocky surface

Pyroclasts

all broken materials from a volcano

Tephra

loose pyroclasts classified as bombs, blocks, or ash

Tuff

a rock from the cementation of tephra

Decompression Melting

upward movement of the mantle to an area of low pressure

Flux Melting

rocks melt when water or carbon dioxide is added

Heat Transfer Melting

hot liquid rock melt surrounding rocks

Partial Melting

minerals with low or high melting points

Basaltic Magma

• 1000-1200 Celsius

• low viscosity and gas content

• high in iron, magnesium, and calcium but low in potassium and sodium

Andesitic Magma

• 800-1000 Celsius

• moderate viscosity and gas content

• commonly erupts from stratovolcanoes

Rhyolitic Magma

• 650-800 Celsius

• high viscosity and gas content

• high in potassium and sodium but low in iron, magnesium, and calcium

Composite Volcanoes

steep-sided cones with explosive eruptions due to viscous lava

• andesitic and rhyolitic lavas

Shield Volcanoes

broad gently sloping cone resembling a warrior’s shield with frequent less violent eruptions

• basaltic lavas

Cinder Cone Volcanoes

has a bowl-shaped and are the simplest and smallest

• basaltic lavas

Plutonism

• formation of intrusive igneous rock

• solidification of magma beneath the Earth’s surface

Fractional Magma Crystalization

when magma cools, it crystallizes in reverse order of partial melting

Phaneritic Magma Texture

crystals are visible to the eye

Aphanitic

crystals are too small to see

Porphyritic

a mixture of coarse and fine crystals

Bowen’s Reaction Series

determined the order of mineral crystallization from a magma

Norman Levi Bowen

A Canadian geologist who made the Bowen’s Reaction Series