Oceanography Lab Final

What frame of reference is most commonly used on maps to show position?

Latitude and longitude

parallels of latitude

lines that run east and west around the globe; parallel to equator

meridians of longitude

imaginary vertical lines, running north to south, perpendicular to equator

vertical exaggeration

vertical scale/horizontal scale

Interpolation

estimating a value within the range of measured data

extrapolation

Estimating a value outside the range of measured data.

contours

lines drawn on a figure that connect data of equal value. Ex: temperature, depth, height, pressure.

scale

distance represented on map/distance represented on earth

3 rules of contours

1. Can never cross 2. can close in upon itself (underwater mountains, valleys). 3. Vs that point uphill are troughs, vs that point downhill are ridges.

On a bathymetry map, the contours are lines of constant

depth

theory of isotasy

This theory suggests that the earth consists of blocks of rigidlithosphere, about 100 km thick, which are "floating" in isostatic equilibrium on a plastic region of earth's mantle called the asthenosphere

buoyancy

a rigid body sitting on a fluid will sink into the fluid until the mass of the displaced fluid exactly equals the total mass of the rigid body.

density

mass of a substance divided by its volume, and is measured in grams per cubic centimeter

continental crusts

averages 35 km in thickness and has a

composition close to granite (density 2.7 - 2.8 g/cm3 )

oceanic crusts

thinner (avg. 5 km) and is composed of basalt (density 3.0 g/cm3 )

Atlantic type continental margins

wide, gently sloping (0.1°)continental shelf, a steeper (4°) continental slope descending to the deep sea, and a flatter (0.2°) continental rise at the base of the slope formed by accumulation of sedimentary materials. no plate boundary, low tectonic activity.

Pacific type continental margins

characterized by a narrow shelf and slope descending into a deep marginal trough, or trench, generally parallel to the continental margin. also characteristic of some large island arcs. high tectonic activity.

turbidity currents

These are short lived, gravity-induced currents consisting of mixtures of sediment and water which flow downslope as a density current. the primary means by whichterrigenous (land-derived) sediment is transported from shallow water onto the deep oceanfloor.

Submarine canyons

steep-walled, V-shaped valleys that incise into continental shelves and slopes and open out at depth onto the continental rise. associated with the mouths of large rivers. Fan-shaped sediment deposits merge to form the continental rise which in turn merges with the abyssal plain.

mid-ocean ridge and rise system

This chain of mountains is 60,000 km long. It often has a central rift valley as much as 1 km deep and a rugged topography on its flanks. stands 1 to 3 km above the deeper ocean basin and is frequently cut and offset by numerous fracture zones. divergent plate boundaries, offset by perpendicular fractures. basaltic magmas rise to the surface and are extruded as lavas onto the oceanfloor. This example represents an advanced stage of rifting and is characterized by relatively slow rates of spreading (1 to 8 cm/yr, half-rate). ex: mid atlantic ridge

fracture zones

inear zones of irregular topography on the sea floor,10 to 100 km wide and up to 3500 km long. haracterized byescarpments that can be from 100 to 4000 m high and separate regions of theseafloor of different depths

abyssal hills

typify the topographic province of most of the deeper oceanbasins where water depths are typically ~5 km. This province is covered by muchmore sediment than the rugged flanks of the midocean ridge system.

abyssal plains

found near some "Atlantic" type continental margins where sediments from turbidity currents have flowed off the continental rise and spread out over the ocean floor producing extremely flat stretches of the ocean floor. roughly 40% of the ocean floor.

Archimedes' Principle

the buoyant force on an object is equal to the weight of the fluid displaced by the object

mantle

higher density material below crust and above outer core ~ 3.3 g/cm3. hot solid material between crust and core.

core

most dense layer composed primarily of iron

Lithosphere

the solid, outer layer of the earth that consists of the crust and the rigid upper part of the mantle

Asthenosphere

the upper layer of the earth's mantle, below the lithosphere, in which there is relatively low resistance to plastic flow and convection is thought to occur.

continental shelf

gently sloping depositional surface extending from the shoreline to the continental slope

continental slope

relatively steep surface seaward of the continental shelf.

continental rise

gently sloping depositional surface at the base of the continental slope

shelf break

at ~140 m depth separates the shelf and slopeContinental Margins

plate tectonics

According to the theory, the outermost division of the Earth consists of cool, rigid lithospheric plates that are in constant motion, being driven by the internal heat of theEarth. These plates are about 100 km thick and float on a hotter, more plastic region of the upper mantle called the asthenosphere

subduction

in regions where plates converge, one lithospheric plate is forced down into the mantle beneath the other plate

magmatic arcs

chains of volcanoes that lie parallel to trenches and above subducted slabs of lithosphere

transform fault

where two plates are moving in parallel but opposing directions; in other words, the plates slide past one another. heat flow is low. Can occur on continents (shallow seismic activity), however more common on sea floor. low heat flow.

divergent plate margins

Plate boundary where two plates are moving away from each other; magmas derived from the asthenosphere rise upward to fill the gap between the diverging lithospheric plates. ex: gulf of California

Young or 'incipient' ocean basins

Similar in appearance to mid-ocean ridgesbut much more limited in extent. These areas represent intermediate stages of continental rifting and ocean-basin formation. Examples include the Gulf of California and Red Sea

on-land rifting

Continental areas characterized by abnormally high heat flow, extensional (pull apart) faulting and volcanic activity. These areas are thought to represent the initial stages of rifting whereby continents 'drift' apart. A new ocean basin is created between adjacent land masses as they separate. ex: Rio Grande rift

convergent plate boundary

Plate boundary where two plates are moving toward each other, usually one plate is subducted beneath the other. can be head on or oblique. Heat flow is low at trenches and high at volcanic arcs.

Oceanic plate-oceanic plate convergence

Convergence characterized by the subduction of one oceanic plate beneath another oceanic plate, forming deep ocean trenches and their associated volcanic island arcs. he more dense (older, and therefore colder) plate issubducted, with the less dense (younger, warmer) crust forming the overriding plate. e.g., Tonga, Aleutians

Oceanic plate - continental plate convergence

Characterized by subduction ofhigh-density oceanic plate beneath a lower-density continental plate, leading to theformation of an ocean trench adjacent to the continent with a chain of volcanicmountains on the continent. e.g., Andes, Cascades

Continental plate-continental plate convergence

neither of the low-density continental plates can be subducted into the relatively dense mantle. The

intense compression of pre-existing continental rocks forms linear belts of folded mountains along the boundary (suture zone) where convergence occurs. e.g., Himalayas, Alps

transform plate boundaries

Margins where two plates neither converge nor diverge, but slide past each other in parallel, but opposing directions. ex: san andreas fault

ridge transforms

faults oriented perpendicular to the axes of mid-ocean ridges,offsetting the ridge axes. The transform fault between offset ridges is seismically-

active. Seismically inactive fracture zones extend away from the ridge segments.Ridge transforms are associated with shallow-focus seismic activity

on land transforms

Transform faults that develop where two continental blocks slide past each other.

intraplate regions and hotspots

Stationary plumes ofmagma erupt through aplate that is moving over it. Forms chains of extinct volcanic islands terminating at the active(youngest) volcanic island. e.g., Hawaiian islands,Emperor Seamounts

genetic classifications

distinguish sediments according to the process by which they originate.

descriptive classifications

distinguish sediments by differences in texture orcomposition.

compositional classifications

consider differences in mineral content, chemicalcomposition, or, in the case of biogenic sediments, the most abundant biological constituent

terrigenous sediment

Sediments derived from weathering of the continents. Erosion by rain, rivers and glaciers (glacial, marine sediments) delivers sediments from the continents to the oceans where they are deposited. usually dominant along continental margins and in the deeper portions of the ocean basins.

biogenic

Sediments that originate by biological processes such as the secretion (growth) of skeletalmaterials by marine organisms. Only a small fraction of biogenic sediment is actually organicmatter. Most biogenic sediment is biologically produced inorganic matter, including skeleta lremains of both microscopic, single-celled organisms, and macroscopic, multi-cellular organisms

Chemogenic

Inorganic sediments that originate by the precipitation of minerals inside the sediment (e.g. from seawater)

volcanogenic

Sediment that originates from volcanic eruption or weathering of volcanic material.

Cosmogenous

Inorganic sediments that originate by the accumulation of materials from outer space

Turbidites

deposits of flows of terrigenous sediment that are transported down canyons and out onto abyssal planes

manganese nodules

black, lightweight objectsthat show concentric layering. They are commonly found on the deep sea floor in regions ofslow sedimentation (e.g. the deep-ocean basins). The nodules, on average, are composed of 64%MnO 2, 33% Fe2O 3, and 3% of mixed Ni, Co, and Cu.

Hydrothermal Sediments

produced at mid-ocean ridges. Cold seawater percolates throughfissures near the ridge crest. This water is then heated by hot rocks under the ridge, and itleaches metals out of the basaltic oceanic crust. As the metal-rich hydrothermalfluids mix with seawater and cool, oxides of Mn and Fe precipitate and are deposited at the ridgecrest.

The distribution pattern of marine sediments is controlled by 3 processes:

1) production,2) dilution, and 3) destruction (or preservation)

carbonate compensation depth

Depth of the ocean below which calcium carbonate, shells and skeletons dissolve and do not accumulate. Deep, cold waters with high CO 2 concentrations are corrosive for carbonate. depth at which rate of dissolution of CaCO3 is equal to its rate of accumulation

the density of seawater _____ when salinity increases

increases

the density of seawater _______ when temperature increases

decreases

measurements scientists can use to determine seawater salinity are

refraction of light, conductivity, weighing before/after water evaporation

average salinity of open sea water?

35

typical ph of sea water?

8

residence time calculation

amount of element in the ocean/rate of removal (or addition) from the ocean

acid

any compound that, when dissolved in water, releases hydrogen ions (H + , also called "protons"because), increasing their concentration in solution

alkaline (base)

one that dissociates in water releasing hydroxyl ions (OH - ) into solution. (high pH)

mixed layer

the surface layer of the ocean that is mixed by wind action

Thermocline

the transition layer between the warmer mixed water at the surface and the cooler deep water below. the temperature decreases rapidly from the mixed layer temperature to the much colder deep water temperature. As also the density of the water changes quickly with temperature, we also call this zone pycnocline.

Surface circulation of the oceans is primarily driven by

winds

Coriolis effect

the apparent deflection of a moving object (like air or water) caused by the Earth's rotation. It causes objects to curve to the right in the Northern Hemisphere and to the left in the Southern Hemisphere.

Ekman transport

the net transport of wind-driven ocean currents is at an

angle (up to 90 ̊) to the prevailing wind. deflected to the right of the prevailing wind direction and in the southern Hemisphere is to the left.

subtropical gyres

the closed-loop pattern of surface ocean currents around the margins of the major ocean basins; the flow is clockwise in the Northern Hemisphere and counterclockwise in the Southern Hemisphere. hey extend from theEquator to about 45 ̊N and 45ºS. They are driven by the trade winds at low latitudes and the westerlies at higher latitudes. As the western boundary currents proceed to higher latitudes they are deflected by the Coriolis effect and driven by the westerlies to form an east-flowing current which is the high-latitude portion. On the eastern margins of the oceans, cold eastern boundary currents flow toward the Equator.

The most important sources of the deep water of the oceans are in

the polar-subpolar North Atlantic and in the Antarctic

isopycnals

Near the high-latitude ends of the subpolar gyres, surface waters tend to converge andmix. This forms water of intermediate density that sinks below the surface, but is not denseenough to sink below NADW or AABW

the intertidal zone

the narrow belt along the shoreline lying between the lowest and highest tide marks.

waves

Keep organisms moist, increase dissolved oxygen, bring food, and remove wastes.
- Rip sessile organisms from the substrate and bury some bottom dwellers in
sediment.
- Extend intertidal zone above high tide, creating the supratidal zone, a "splash zone".
- Are small to nonexistent in protected bays, lagoons, and estuaries. Unique intertidal
communities with sharp zone boundaries are found in these environments.
- The greatest diversity and abundance of life in the intertidal zone occurs where wave
force is slightly diminished, as at the semiprotected environment of Palos Verdes.
Much of the wave energy is dissipated on the headlands to the north.

tides

- Affect all ocean shorelines, but tidal range varies locally causing wide or narrow
intertidal zones (Southern California`s tidal range is about 3 meters).
- Tides affect organisms by periodically submerging and then exposing them to the
sun and air.

substrate

a substance in or on which an organism lives, grows, or is attached to.

sand/mud

support mostly benthic, infaunal species capable of living in turbid water. In such environments, species diversity is moderate, and abundances are low.

cobbles

support species hardy enough to resist the action of colliding cobbles in the surf. Diversity and abundances are low

rocks

supports the highest diversity and abundance. The specific community is determined by the rock’s texture and degree of hardness. Some substrates are soft enough that some animals can excavate borings, enabling them to live within the rock. Numerous habitats are possible along a rocky shore: tide pools, crevices, overhangs, exposed surfaces, protected surfaces, etc. The degree of habitat diversity tends to be correlated with species diversity (i.e., the greater the number of habitats -
the greater the species diversity)

predation

often control the lowest depth at which their prey can live. Prey species that can adapt to the harsher physical conditions of a higher zone escape and may become locally abundant, in some cases dominating a zone. eat individuals that live too close to the top of their zone.

The coastline of western North America is especially diverse because

1) the intense coastal upwelling of nutrient-rich bottom waters occurs here, seasonally providing an abundance
of nutrient-rich bottom water; (2) there is almost complete freedom from winter sea ice as far north as Alaska; and (3) a low diversity of herbivorous-fish species allows algae to grow in
abundance, thus supporting large numbers of invertebrate herbivores.

phytoplankton

photosynthesizing plankton – are the original source of food for nearly all higher microscopic and macroscopic marine organism

pelagic organisms

organisms living in the surface waters are
either unable to swim or have limited swimming ability. However, many of these plankton are able to control their vertical position in the water column

nektonic organisms

those which expertly swim in the pelagic zone and are able to move both laterally and vertically

benthic organisms

live on, in, or near the seafloor, also known as the benthic zone.
Those that live on the seafloor sediment are termed epifaunal. Organisms living near the sea floor can either be mobile – those that crawl or swim or sessile – those that are attached to a fixed structure. Lastly, infaunal benthos are the organisms that live within sediment.

coccoid bacteria

are so small (0.2-2.0 μm) that their
relative contribution and importance was overlooked until just recently. In fact, the
photosynthesizing bacterioplankton are the most abundant photosynthetic organisms on Earth
and are estimated to compose half of all the photosynthetic biomass in the ocean

diatoms

equally important primary producers in the ocean, estimated to
contribute up to 45% of the total oceanic primary production. Members of the algae (plant-like) protists. Diatoms produce a silica (SiO 2 ) mineralized cell wall

Dinoflagellates

members of the protozoa (animal-like) protists. Oddly, about half are phytoplanktonic photosynthesizers, and the other species are zooplanktonic heterotrophs. produce a toughened cell wall with cellulose

red tides/algal blooms

concentrations of dinoflagellates, causes water to appear red. Can be dangerous if at high levels.

copepods

a group of small crustaceans, are by far the most important primary consumer zooplankton. Covered in an armored exoskeleton composed of chitin (an organic
complex carbohydrate), which they molt and replace routinely.

Krill

a group of small shrimp-like crustaceans, much larger than the copepods, and
are an important food source for fish, seabirds, seals, manta rays, whale sharks, and the largest
animals of all, the baleen whales. assemble in dense swarms, a defensive tactic to confuse smaller predators that would
like to pick out single individuals. They also practice vertical migration like copepods. Can
swim against weak currents, thus they are in a gray zone between true plankton and nekton

radiolarians

amoeboid protozoans which produce amazingly complex and intricate silica (SiO 2 ) skeletons, typically 0.1-2 mm in size. Skeletons have spherical and conical forms with geometrical latticework patterns, with or without numerous radial spines.
Regulate buoyancy with intracellular low-density fats and possess spiny exteriors which increase their surface area which helps counter sinking.

foraminiferans

amoeboid protozoans which produce a globular or spiraled,
chambered calcareous (calcium-carbonate, CaCO 3 ) test (shell), typically 0.1-1.5 mm in size.
They capture food with reticulating pseudopoda, fine strands of cytoplasm that branch and merge
to form a dynamic net.

macroplankton

They include krill, discussed above, pteropods, which
are planktonic snails, and many types of gelatinous plankton, the best known of which are
jellyfish

autotrophs

the producers in the food chain, which produce
complex organic compounds (often by photosynthesis) from simple inorganic compounds (such
as CO 2 , nitrate, etc.) and an external, inorganic source of energy (such as sunlight) from the
physical environment.

heterotrophs

the consumers in the food chain, which may feed on
autotrophs or other heterotrophs for chemical-organic energy and organic-carbon compounds
used for growth and development.