Active Earth Flashcards
basic layers of earth
inner core, outer core, mantle, crust
uppermost layer of mantle + crust
lithosphere
oceanic crust is
Basaltic
Continental crust is…
Granatic
father of continental drift
Alfred Wegener
Ocean floor has
Many structures
Large and long connected underwater mountain chains
Mid-ocean ridges
Incredibly deep areas on the ocean floor
Ocean trenches
Ocean crust made up of
Basalt
Seafloor spreading
Explains magnetic striping
Seafloor spread process:
Subduction
Combining and modifying seafloor spreading and continental drift resulted in
Plate tectonics theory
According to Plate tecnotics
Pieces of the earths lithosphere move in relation to each other
Earths lithosphere divided into
Plates
Plates
Rigid, they deform by earthquakes
Passive margins
Found at the edge of the continent where the oceanic crust is on the same tectonic plate, not characterized by volcanos and earthquakes
Active margins
The edge of a continent coincides with a plate boundary, earthquakes and volcanic activity
Divergent boundary
Found between two plates that move in opposite directions
Most common divergent boundary
Mid-ocean ridge and continental rift
Convergent boundary
Two plates collide
Convergent boundary types (3)
Continental-continental
Continental-oceanic
Oceanic-oceanic
Continental oceanic convergence:
Ocean crust is denser
Leads to continental arc volcanoes
Oceanic-oceanic convergence:
Two ocean crusts collide
Island arc volcanoes
Continental-continental convergence:
Two continental crust collide, crust pushed up
Forms a large mountain belt
Transform boundaries:
Two plates move alongside and past each other, not directly towards
Transform boundaries main areas
Near mid-ocean ridges
Cutting across continents
Hot spots
A plume of magma originates in the lower mantle and rises through the crust
Plate movements currently
A few centimeters per year
Was the Flood global?
Yes, a local flood could not last a year and could not judge humanity
3 main types of forces rocks experience in the Earth
Compressional
Tensional
Shear forces
Rocks can bend (….) or break (….)
Folds, faults
Two basic types of folds
Synclines- U shaped
Anticlines- upside down U
Two types of large scale folds
Domes
Basins
Types of faults (3)
Dip-slip faults: vertical movement
Strike- slip faults: horizontal movement
Oblique-slip faults: combination
Types of dip-slip faults
Normal fault: a wall moves down
Reverse fault: a wall moves up
Thrust fault: reverse fault with very shallow angle (<10º)
Earthquakes occur when
Stresses build up in the earth and rocks fracture, leads to vibration that can cause damage
Waves that propagate
Seismic waves
Epicenter
Line drawn in the surface from the focus
Seismic waves
Wave of energy from an earthquake, body waves or surface waves
Body waves (2 types)
Primary waves (compression) and secondary waves (transverse)
Surface waves (2 types)
Love waves (back and forth), rayleigh waves (up and down)
Measuring an earthquake
Seismometer (instrument to detect)
Seismographs (detect and record)
Seismograms (printout)
Scales for earthquakes
Magnitude (richter) and intensity (mercalli)
Results of earthquakes
Tsunamis
Volcano
A rupture in earths crust that allows lava gases and ash to escape
Ring of fire
Where most of the volcanoes on earth occur (surrounding Pacific Ocean)
Volcanic materials
Water vapor, ash, lava, carbon dioxide
Lava (2 types)
Pahoehoe (ropey)
Aa (rough)
Volcanic danger
Phriclastic flow: avalanche down the slope (glowing one: Nuée ardente)
Lahars: mudflows of ash, melted ice and snow
3 types of volcanoes
Cinder cones
Composite cones
Shield volcanoes
Cinder cone volcanoes
Smallest type
Steepest slopes
Composite cone volcanoes
Most violent
Intermediate slopes
Shield volcanoes
Largest
Shallowest slopes
Large circular crater
Caldera
