M2 Subtopic 4 Flashcards
The Four Layers of the Earth.
Crust, Mantle, Outer Core and Inner Core
the outermost layer of the Earth, comprising the crust and the uppermost part of the mantle. It is rigid and brittle, divided into tectonic plates that move and interact at their boundaries
Lithosphere
lies directly beneath the lithosphere and is part of the upper mantle. It is a semi-fluid layer that can flow and deform, allowing the rigid lithospheric plates to move on top of it
Asthenosphere
Refers to the changing earth’s surface caused by tectonic forces that accumulate in the crust and then cause earthquakes.
Crustal Deformation
the bending, tilting, and breaking of Earth’s crust; the change in the shape of rock in response to stress
Deformation
a condition of gravitational and buoyant equilibrium between Earth’s lithosphere and asthenosphere.
Isostasy
Factors Influencing Rock Deformation
High/low Temperatures. High Pressures, Rock Composition, Time
can make rocks more ductile, leading to plastic deformation
High temperatures
typically result in brittle deformation
Low temperatures
can cause rocks to deform plastically. At lower pressures, rocks are more likely to fracture
High Pressures
Different types of rocks deform in different ways; for example, sedimentary rocks often deform plastically, while igneous rocks tend to fracture
Rock Composition
is the force applied per unit area within rocks. It can be categorized into different types based on the direction and nature of the force.
Stress
Squeezes rocks together, causing them to shorten and thicken. Commonly associated with folding and reverse faulting
Compressional Stress
Pulls rocks apart, causing them to lengthen and thin. Associated with normal faulting
Tensional Stress
Causes rocks to slide past each other horizontally. Associated with strike-slip faulting
Shear Stress
the deformation or change in shape of rocks as a result of applied stress
Strain
Temporary and reversible change in shape. Rocks return to their original shape when the stress is removed.
Elastic Strain
Permanent change in shape that occurs without fracturing. Rocks remain deformed even after the stress is removed.
Plastic Strain
Permanent change in shape that results in fracturing or breaking of rocks.
Brittle Strain
occurs due to compressive forces that shorten and thicken the Earth’s crust. It often results in the formation of mountain ranges
Folding
Fold Parts
Limbs
Axis
Axial Plane
Types of Folds
Anticline
Syncline
Monocline
An upward-arching fold with the oldest rocks at the core. Arch shaped
Anticline
A downward-arching fold with the youngest rocks at the core. Bowl shape
Syncline
A fold in which rock layers dip in one direction between horizontal layers. Formed when one part of Earth’s crust moves up or down relative to another part
Monocline
occurs due to tectonic forces that cause rocks to break and move. The type of stress determines the kind of fault that forms
Faulting
A fault in which the hanging wall moves downward relative to the footwall. * Ex. The Great Rift Valley
Normal Fault
Compression causes the hanging wall to move upward relative to the footwall
Reverse Fault
a special type of reverse, the fault plane is at a low angle.
Thrust Fault
The rock on either side of the fault plane slides horizontally in response to shear stress. It slides or slips, parallel to the direction of the length, or strike, of the fault. Commonly occurs in transform boundary
Strike Slip Faults
Types of Boundaries
Continental-Continental Convergence
Divergent Boundaries
Transform Boundaries
Plates slide past each other horizontally. Crust is neither created nor destroyed
Transform Boundaries
Caused by the movement of plates along fault lines
Earthquake
Occurs at divergent and convergent boundaries where magma reaches the surface
Volcanic Activity
Result of plate collisions and compressions
Mountain Building
Due to seafloor spreading at mid-ocean ridges
Ocean Basin Formation
Formed by the bending of rocks under pressure, common at convergent boundaries
Folds
Cracks where rocks have slipped past each other, common at transform boundaries.
Faults
Deep valleys in the ocean floor at subduction zones (e.g., Mariana Trench).
Trenches
Formed by rising magma from subduction zones or divergent boundaries (e.g., Pacific Ring of Fire).
Volcanoes
Formed at divergent boundaries where the crust is pulling apart (e.g., East African Rift)
Rift Valleys
Formed by the collision and compression of continental plates at convergent boundaries (e.g., Himalayas, Andes).
Mountain Ranges
Provided the initial idea that continents move
Continental Drift
Offered a mechanism for how continents could move apart
Seafloor Spreading
Unified these ideas into a comprehensive theory explaining the movement and interaction of Earth’s plates, shaping the surface over geological time scales
Plate Tectonics
