Ocean 100 Exam 1

science

study of the physical, natural world through observations & experiments

scientific method

principles & empirical processes of discovery & demonstration considered characteristic of/ necessary for scientific investigation

what are the steps of the scientific method?

(1) observation
(2) hypothesis
(3) testing/experimenting
(4) theory

hypothesis

idea proposed to explain 1 or more facts; must be testable & potentially false

scientific theory

structure of ideas that explains a large, diverse number of facts

what are the 3 factors of scientific theory?

(1) supported by abundant evidence
(2) rigorously tested
(3) parsimonious (most efficient, simplest explanation)

what are some examples of scientific theory?

- plate tectonics (geology)
- evolution (biology)
- gravity, relativity (physics)
- big bang (astronomy)

what are the fields involved in oceanography?

(1) geology
(2) geography
(3) biology
(4) chemistry
(5) physics
(6) astronomy
(7) engineering

what are some examples involving geology?

seafloor tectonics, coastal processes, sediments, hydrologic cycle

what are some examples involving geography?

wind belts, weather, coastal landforms, world climate

what are some examples involving biology?

fisheries, ecological surveys, microbiology, marine adaptions

what are some examples involving chemistry?

dissolved components, temperature dependence, stratification/density, chemical tracers

what are some examples involving physics?

currents, waves, sonar, thermal properties of water

what are some examples involving astronomy?

tidal forces, oceans on other planets, origin of water, origin of life

what are some examples involving engineering?

machinery used by scientists to explore the deep-ocean floor

what are the earth's 4 spheres?

(1) lithosphere
(2) asthenosphere
(3) mesosphere
(4) outer & inner core

cross-sectional view

side view (ex. cutting a cake, able to see its layers)

map view

bird's eye view,

block diagram

3-d view

mercator projection

2-d depiction of spherical earth; lands towards poles are magnified/distorted

what are the 5 oceans?

(1) pacific
(2) atlantic
(3) indian
(4) arctic
(5) antarctic

which ocean is the largest & deepest? why?

pacific; has the most trenches (ex. mariana trench)

which ocean is the shallowest? why?

arctic; heavily surrounded by wide, continental shelves

what percentage of the earth's surface is ocean?

71%

what percentage of water on earth is ocean (salt/saline water)?

97%; other 3% (fresh water) are found in ice caps, lakes, & rivers

what is the average depth of oceans?

3,800m (12,500ft)

how old is the oldest sea floor?

180my old

what is the average temperature of oceans?

4°C (38°F)

approx. how old are oceans?

4by old

what are the most abundant elements found in oceans?

hydrogen, oxygen, chloride, sodium

energy

capacity to do work

what are the 2 types of energy?

(1) kinetic energy
(2) heat energy

how are heat & kinetic energy related?

heat < - \> cold is made possible through motion

how are kinetic & heat energy applied to oceanography?

convection of mid-ocean ridges (heat rises & expands, later becomes cold, contracts, & moves back down)

what are the 2 sources of heat energy for the earth?

(1) solar: sun
(2) geothermal: interior of the earth

convection

physical movement of liquid, gas, & viscous solid

how do convection cells move w/in earth?

slow, circular movement of hot rock in the mantle

how do convection cells relate to plate tectonics?

new ocean crust is created at ridges - \> split apart - \> move away from ridges - \> later disappears into the deep earth at trenches

how does density & temperature relate?

- hot, less dense
- cold, more dense

what is thermal expansion of the ocean? where does it occur?

happens when water has low density & high energy (warm); happens in tropical/subtropical regions (ex. gulf of mexico)

what is thermal contraction of the ocean? where does it occur?

happens when water has high density & low energy (cold); happens in polar/sub-polar regions

density

mass/volume; expressed as grams per cubic centimeter (g/c^3)

how is density applied to rock & water?

- basalt (more dense); makes up the ocean floor
- granite (less dense); rises up to form the continental crust

how is density applied to convection?

- hot, less dense, rises - \> buoyancy
- cold, more dense, sinks - \> gravity

how is density connected to plate tectonics?

oceanic crust (more dense) subducts under continental crust (less dense)

supernova

great explosion of a star

solar nebula

cloud of gas & space dust

solar disk model

(1) a huge cloud of dust & gases contracts
(2) most of the material is gravitationally swept toward the center, producing the sun, while the remainder flattens into a disk
(3) small eddies are created by the circular motion
(4) in time, most of the remaining debris forms the planets & their moons

when did the solar disk model happen?

4.6by ago

explain the density differentiation of the earth

- denser metals (iron & nickel) - \> core
- lighter, silicate rocks - \> surface

where is the densest material? why?

core b/c gravity pulls denser material (iron & nickel) to the center of the earth

where is the least dense material? why?

surface b/c less dense material (silicate rock) is not as affected by gravity than denser material (iron & nickel)

how were the atmosphere & oceans formed?

volcanic outgassing (h2o condensed & rained down on earth) & icy comets (made of water) fell to earth

what are the major gases of the atmosphere & oceans in order of abundance?

(1) water
(2) carbon dioxide
(3) nitrogen
(4) sulfur dioxide
(5) chloride
(6) methane
(7) ammonium

when did life 1st appear?

3.7by ago

how did our atmosphere get enriched by oxygen? when?

photosynthetic algae brought o2 to the atmosphere; 2.5by ago

when did animals 1st appear?

600my ago

what was the role of asteroids & comets in the mass extinction of the dinosaurs 65my ago? what is the evidence supporting this?

an asteroid hit the earth, killing all the dinosaurs; asteroid crater (10km to 15 km wide) found underneath the yucatán peninsula in mexico

what are the 3 layers of the earth based on chemical composition?

(1) crust
(2) mantle
(3) core

what are the characteristics of the lithosphere?

- cool, rigid, outermost layer
- 100km (62mi) deep
- includes crust & topmost portion of the mantle
- brittle, meaning it will fracture when force is applied to it
- plate tectonic motion occurs here

what are the characteristics of the asthenosphere?

- plastic/molded, meaning it will flow when gradual force is applied to it
- 100 km (62mi) to 700km (430mi) deep
- base of the upper mantle
- hot enough to partially melt portions of most rocks

what are the characteristics of the mesosphere?

- 2,885km (1,800mi) deep
- corresponds to the middle & lower mantle
- rigid, most likely due to increased pressure at these depths

what are the characteristics of the outer core?

liquid, capable of flowing

what are the characteristics of the inner core?

rigid, does not flow (increased pressure at the center of the earth keeps the inner core from flowing)

what are the basic premises of plate tectonics?

according to the theory, the outermost portion of earth is composed of a patchwork of thin, rigid plates that move horizontally w/ respect to 1 another

what is the evidence supporting plate tectonics?

(1) supercontinent/pangea
(2) echo sounding & sonar
(3) sea floor spreading
(4) ages of the ocean floor
(5) earth's magnetic field
(6) plate boundaries
(7) world distribution of earthquakes

what are the layers of the earth directly involved in tectonic processes? how do they work?

lithosphere & asthenosphere; lithosphere is broken up into plates which move over the asthenosphere

continental drift

idea that continents fit together like pieces of a jigsaw puzzle & are slowly drifting across the globe

who was responsible for the continental drift?

alfred wegner

what is the evidence supporting continental drift?

(1) continental fit
(2) fossils
(3) rocks & mountains
(4) climate
(5) glacial deposits

what is pangea?

during the geologic past, the continents collided to form a large landmass/supercontinent

how long ago was pangea?

200my ago

what is happening to the continents now?

they are drifting further apart

how did geologists 1st measure the ocean depths?

echo sounding/sonar

what is the equation of sonar? how do we use it?

(velocity of sound x time)/2; used to figure out the depths of the ocean

what is the speed of sound in water?

1,500m/s

why is there a mountain system in all oceans?

divergent boundaries (mid-ocean ridges) form huge, volcanic, mountain chains

what does convection have to do w/ mid-ocean ridges?

heat rises to form mountains, cools, & then sinks back down to the sea floor

explain the ages of the sea floor

as you move farther away from ridges, the sea floor gets older

where is the oldest sea floor found?

near coasts & continents

where is the youngest sea floor found?

near mid-ocean ridges, where they are produced

paleomagnetism

study of earth's ancient, magnetic field

how is paleomagnetism recorded in the rocks of the ridge? what does earth's magnetic field have to do w/ it?

(1) particles of magnetite in magma align themselves w/ earth's magnetic field b/c it is fluid
(2) molten material cools down, freezing the magnetite particles into position, thereby recording the angle of earth's magnetic field of that time & place

how frequently does earth's polarity change?

every 500,000 years

what is our current polarity?

north

how does paleomagnetism imply plate movement?

ex. the magnetic, polar wandering paths for north america & eurasia do not align, implying that both continents have moved throughout geological time

where is earth's magnetic field generated? why?

at the core; the flow of liquid iron generates electric currents, therefore producing magnetic fields

what are the 3 plate boundaries?

(1) convergent
(2) divergent
(3) transform

convergent boundary

when 2 plates collide

what are the 2 types of convergent boundaries?

(1) subduction
(2) continental collision

subduction

oceanic plate goes under continental plate due to slab pull gravity b/c it is more dense

where do we see subduction most?

near deep, ocean trenches

what does subduction cause?

huge earthquakes as oceanic plates bend downward & slowly plunge back into earth's interior (more friction against a larger surface area)

what are some examples of a convergent boundary?

andes, japan, tonga, cascades, himalayas

divergent boundary

when 2 plates rift apart

what are some examples of a divergent boundary?

east pacific rise, mid-atlantic ridge, iceland

transform boundary

when 2 plates slide past each other in opp. directions

what are some examples of a transform boundary?

san andreas fault

continental collision

when 2 continental plates collide b/c they are both not dense enough to sink

where are earthquakes & volcanoes mostly distributed?

near ridges