Unit 3: Rock Cycle Flashcards
(14 cards)
Plate Tectonic Theory
The Plate Tectonic Theory is a scientific concept that explains how Earth’s outer shell is divided into large, rigid pieces called tectonic plates.
Continental Drift Theory
The Continental Drift Theory was proposed by Alfred Wegener in 1912. It suggests that the Earth’s continents were once joined together in a single large landmass called Pangaea
Evidence: Matching coastlines, Fossil evidence, Rock formations and mountain formations and Climate evidence
Convergent Boundaries
When two plates move toward each other, they collide and create various landforms depending on the type of crust involved
Oceanic-Continental Convergent Boundary
Example/Result: Andes Mountains (Volcanic Mountains)
Process: The oceanic plate subducts beneath the continental plate, causing volcanic mountain formation.
Oceanic-Oceanic Convergent Boundary
Example/Result: Philippine Islands, Japan (Volcanic Island Arc)
Process: One oceanic plate subducts beneath another, forming a chain of volcanic islands.
Continental-Continental Convergent Boundary
Example/Result: Himalayas, Alps (Folded Mountains)
Process: Two continental plates collide, causing the crust to form large mountain ranges.
Divergent Boundaries (Spreading Plates)
When two plates move away from each other, new crust forms.
Continental Divergent Boundary
Example/Result: East African Rift (Rift Zones)
Process: The continental crust stretches and splits, forming rift valleys.
Oceanic Divergent Boundary
Example/Result: Mid-Atlantic Ridge (Mid-ocean Ridge)
Process: Magma rises to fill the gap between diverging oceanic plates, forming new oceanic crust and underwater mountain chains.
Transform Boundaries (Sliding Plates)
When two plates slide past each other horizontally, they create faults.
Transform Boundary
Example/Result: San Andreas Fault (Earthquakes)
Process: The plates grind past each other, causing intense friction and earthquakes.
Ring of Fire
a horseshoe-shaped belt of seismic activity encompassing the edges of the Pacific Plate. It’s a direct consequence of plate interactions. Here, numerous volcanic eruptions and earthquakes occur due to the subduction (one plate moving under another) of oceanic plates beneath lighter continental plates.
Crust
The outermost layer of the Earth is solid and relatively thin compared to the other layers
a) Continental crust
Thicker and less dense, composed mainly of granite
b) Oceanic crust
Thinner and denser, composed mainly of basalt
Mantle
The layer beneath the crust extends to a depth of about 2,900 kilometres. Composed of semi-solid rock that can flow slowly
a) Upper mantle - Contains the asthenosphere, a semi-fluid layer that allows tectonic plates to move
b) Lower mantle - More rigid and extends to the outer core
Core
The innermost layer of the Earth, consisting of two parts
a) Outer Core - Liquid layer composed mainly of iron and nickel
b) Inner Core - Solid due to immense pressure, composed mainly of iron and nickel
Rock Types
add: Sedimentary, Igneous and Metamorphic
Earthquakes
a sudden shaking of the Earth’s crust caused by plate movement and release of built-up pressure. The focus is where the pressure is released underground, the epicentre is directly above it
Short-term impacts
Social: Injuries, deaths, destroyed homes
Economic: Damaged businesses, looting, disrupted trade
Environmental: Destroyed buildings, landslides, coastal flooding
Long-term impacts
Social: Disease spread, homelessness, people living in refugee camps
Economic: High rebuilding costs, reduced investment, income loss
Environmental: Loss of natural and cultural landmarks
metamorphic rocks
METAMORPHIC rocks are formed under the surface of the Earth from the change that occurs due to intense HEAT and PRESSURE. Examples of this rock type include gneiss and marble.
igneous rocks
IGNEOUS rocks are formed when MAGMA COOLS AND HARDENS. Examples of this rock type include basalt and obsidian.
sedimentary rocks
SEDIMENTARY rocks are formed from particles called SEDIMENTS that are COMPACTED AND CEMENTED. Examples of this rock type include conglomerate and limestone.
