Chapter 2 Flashcards
In the Southern Hemisphere … Of the total area is ocean
80%
Four large basins
Pacific, Atlantic, Indian, arctic
What is the oldest and deepest
Pacific
How long do scientist believe earth originated
- 5 bill. Years ago Big Bang THEORY
- 7 Big Bang
- 5 organisms
What is an essential element to sustain life
Location relative to sun allows water to stay liquid
Core
Innermost layer, solid inner core liquid outer, iron rich magnetism
Mantle
Middle layer , semi plastic
Crust
Outermost layer , thinnest portion
Oceanic crust
Basalt , denser than continental
Continental
Granite, construction mainly, less dense than oceanic
Oceanic v. Continental
3.0 density, 2.7 g/cm^3 5 km 20 to 50 km thick Young old Dark light Iron, magnesium / sodium potassium calcium aluminum
Continental drift was proposed in and by
1912 Alfred wegner
Single supercontinent Pangea
When did Pangea break up
180 mill. Years ago
Why was it not widely accepted
Not explain how
Main features of plate tectonics
Covered by crustal plates
Constantly moving spreading in center and sinking at edges being regenerated
Convections currents assist movement
Heat from mantle drives currents
Mid oceanic floor rise from … What are they
Ocean floor , submarine volcanic mountains
What is ridge displaced by
Faults in earths crust called transform faults
Where is very little sediment located and what does it mean
At bottom near mid ocean ridge, not old
Where does sediment get thicker
Farther away from ridge, older, sediment has had time to accumulate
At random intervals earth’s magnetic field….. New rock formed from… Record the orientation of earths ….. at the same time … Cools
Reverses , magma , magnetic fields, magma
Studies of sea floor records stripes of…. That are ….. To the mid ocean ridges. This is evidence of
Alternating magnetization, parallel, continuous formation of new rocks at ridges
As new rocks are formed
Olde dis pushed away forming patterns
Chains of islands are found throughout oceans especially in
Pacific, island arcs
Island arcs are situated along what? No on which side
Deep sea trenches, continental side , other side is sub ducted
Underneath the earth’s crust is a layer of
Heated rock driving creation of new ocean floor
Pangea was surrounded by single world ocean
Panthalassa
What sea separated Eurasia from Africa
Tethys
How long ago were Panthalassa and Tethys in place
200 mill.
180 mill. Years ago a rift formed between
North America and South America +Africa
What two continents were formed form Pangea
Laurasia and Gondwana beginning of mid Atlantic ridge
Split up Gondwana
Indian ocean formed
How long ago did rift between soutbamerica and Africa form
135 mill. Joined mid ocean ridge in North Atlantic to form one single mid Atlantic ridge
As the Atlantic Ocean grows the Americas are carried farther away from
Eurasia and Africa
Atlantic Ocean … And Pacific Ocean ….
Grows, shrinks
Lithogenous sediments
Derived from break down of rocks weathering
Biogenous sediments
Derived from skeletons and shells of marine organisms
Biogenous sediments can reveal
Info from the past
Ocean temp. at time microfossils were formed can be determined by ratio of
Magnesium to calcium
Different ratios of oxygen isotopes
Margins of continents are boundaries between
Continental and oceanic crust
Boundaries consist of
Continental shelf landward
Slope
Rise seaward
Continental shelf makes up … Oceans surface area , biologicallyis the
8% richest area of ocean
What is the width of the continental shelf, where is shelf break
1 km to 750, 120 - 400 m
Slope is the … Of the continent , begins at … And continues to…,mint is the …. Part
Edge , shelf break deep sea floor , steepest
Rise is formed by what
Sediments that have been pushed down to continental shelf and slope, underwater river delta
Passive margins
Geologically inactive , flat wide coastal plains , wide continental shelves , gradually sloping slopes
Example of passive margins
East coast of us
Active margins
Intense geological activity , earthquakes volcanoes trenches , steep rocky shorelines, narrow continental shelves , steep continental slopes
Example of active margins
West coast of us
Where were similar fossils founded
South America and Africa
Rock types were found similar in
North America and Europe, Madagascar and India
Coal deposits from tropical plants on artcic islands
Northern continents once occupied tropical latitudes
Alfred Holmes what year
1928 circular convection currents of molten material provide ample force to divide and move continents
Late 1960’s theory of
Plate tectonics .., technology floor was not essentially flat
50000 km long ridges and 11 km deep trenches
Detected pattern of
Alternating magnetic polarity emanated from ridge tops
Volcanic activity and island building occurs most at
Trenches
Who came up with sea floor spreading
Harry Hess and Robert dietz
Divergent boundary
Mid ocean ridges , two plates move away making break or rift , magma rises up making new crust
Convergent boundary
Two plates moving toward each other meet , denser subducts , if both made of continental very little subducts
Instead they buckle and form valleys, ridges, high mountains
Transform boundary
Plates slide along each other in opposite directions
When they get stuck there is a build up of tension , released in earthquake form
What are most geologically active
Zones along plate boundaries
Earthquakes are common among what types of boundaries
All boundaries
Volcanoes are associated with what type of boundaries
Divergent and convergent
Well known plate boundaries that encircles Pacific Ocean and has frequent earthquake and volcanoes is called
Ring of fire
Hot spots
Magma burns through as plate is moving
What is an example of a hotspot
Hawaii
Topography is the study of .
is the study of Earth’s surface features, for the purposes of this activity, it specifically involves the recording and study of the planet’s relief or terrain above sea level.
Bathymetry is
study of Earth’s underwater features for the purpose of this activity, it specifically involves the recording and studying of the planet’s water depth below sea level.
What changes because of typography and bathymetry
Latitude, longitude, elevation, depth
Where is mt. Everest
Eastern Nepal, border of Tibet, Himalayan mountain range
What was mt. Everest named after and what year
Sir George Everest British surveyor general of India
1865
Lowest ocean depth is called and where is it
Challenger deep beneath western Pacific Ocean , Philippine sea in southern end of Marianna’s trench
What was challenger deep named after and when
British survey ship challenger II which surveyed trench in 1951
Other names for Everest
Chomolungma -Tibetan
Sagarmatha- Nepalese
Deodungha- local area Nepalese
Shengmu feng- simple Chinese
Lowest ocean depths is how far from highest peak
6325 km southeast
In the northern hemisphere… Total area is ocean
61%
What two types of structures are found at subduction zones
Volcanoes trenches
What causes trench to form
One plate sinks beneath another
Geologic process at mid ocean ridge
Volcano and earthquake
Black smokers result from
Minerals
Where can we find island arch along trench
Aleutian Islands
