Untitled Flashcards Set

Ocean 100 TA revised Lab Study Guide:

Lab 1: 

• Know conversions:

• Identify longitude and latitude: Locating latitude and longitude means finding the exact position of a place on the Earth's surface by using a coordinate system. 

  • Latitude refers to how far north or south a location is from the Equator,

  • longitude refers to how far east or west a location is from the Prime Meridian. The two coordinates together pinpoint a specific location on a map or globe.

Lab 2: 

• Earthquakes are stronger at subduction zones when compared to divergent because they are deeper

• Nazca Plate: moves right

• South american plate: moves left

• Pacific Plate: left (divergent boundary with nazca plate)

• Explanation: when 2 plates diverge, 1 plate will eventually break off (due to wind + external pressures), this is where the transform boundary occurs… then we diverge again :))

• In stable it is packed: all arrows point right for Nazca Plate and all arrows pointed left for South American Plate.

Lab 3:

• Thickness of ocean layers:

• The Earth's crust is divided into two main types:

  • Continental Crust: Less dense and thicker (about 30-50 km thick)

  • Oceanic Crust: Denser and thinner (about 5-10 km thick).

  • Because of isostasy, the more buoyant, less dense continental crust "floats" higher on the mantle compared to the denser, thinner oceanic crust, which is lower.

  • Isostatic adjustments can affect the height of landforms. For example, when glaciers melt, the land previously compressed by the weight of the ice will begin to rise, a process known as post-glacial rebound.

• Earthquakes: release of accumulating elastic strain within the lithosphere through essentially instantaneous motion along some fault surface (starting point is referred to as  → focus)

• Hot spots: where rising mantle plumes (column of hot, solid material rising from deep within the Earth's mantle, often associated with volcanic activity and the formation of hotspots, where magma reaches the surface to create volcanic islands or landforms.) of asthenosphere melt through the overlying lithosphere and erupt as magma on the ocean floor - sometimes building up high enough to break the ocean surface and form volcanic islands

  • Core and then rises up

• Isostasy: “same standing”; equilibrium or balance of the Earth's lithosphere as it "floats" on the more fluid, deformable asthenosphere beneath it. This concept explains how the Earth's crust adjusts in response to changes in surface load, such as the melting of ice sheets or the accumulation of sediments.

  • when you add mass (such as ice or sediment) to the crust, it will cause that area to sink more into the mantle. Conversely, if you remove mass, the crust will rise. This process is what keeps Earth's surface balanced.

• Isostatic equilibrium: Equilibrium between parts of the earth's crust, which behaves like floating blocks, rising if material is removed and sinking if material is deposited.

• Density is the mass per unit

• volume of a material (g/cm3).

• • Mountain building: at subduction zone the ocean plate is converging with the continental plate, this makes the continental plate rise as accreting the mountain surface

  • In the context of subduction zones and mountain formation, accretion refers to the process where material (like oceanic crust or sediment) is added to a tectonic plate as it moves. In subduction zones, one plate is forced beneath another, and the material can accumulate or "accrete" onto the overriding plate, contributing to mountain formation or the buildup of land.

  • Balancing threshold: comes into play as the weight of the material being accreted at the subduction zone affects the balance of the plates. The continental plate begins to "rise" as material from the oceanic plate is added or accreted.

    • As more material builds up, the continental plate gets thicker, which can cause it to rise higher. However, this rise (or increase in thickness) is also balanced by the forces acting on the plate. The thicker continental crust may lead to the formation of mountain ranges, and the subduction of the oceanic plate continues beneath.

  • balancing threshold: point where the weight of the land plate and the stuff that’s added to it (like the ocean plate pieces) balance out. If the land plate gets too heavy, it might sink a little, and if it gets too light, it might rise. So, the balancing threshold is like a balance scale, making sure that the land plate neither sinks too much nor floats up too much as new pieces are added.

  • This balance helps to form mountains over time, and it's always shifting, like adjusting a tower of blocks so it doesn’t tip over. When the plates "balance" just right, mountains can keep growing.

• When density of  oceanic crust increases: the thickness of the crust riding above the mantle decreases

  • Why?: Denser oceanic crust means it sinks deeper into the mantle because it's heavier. This reduces the portion of the crust that remains above the mantle.

  • The % of crust riding above mantle also decreases when oceanic crust increases in density

• When continental crust thickens: The thickness of crust riding above mantle increases

  • Why?: Continental crust is less dense than oceanic crust, so when it thickens (e.g., through mountain formation), more of it stays above the mantle instead of sinking.

  • When continental crust thickens we have the same density but different regarding thickness and % of crust riding above mantle

  • Why?: Unlike oceanic crust, thickening continental crust doesn’t get denser—it just piles up more material. This means that while the total crustal thickness increases, the amount floating above the mantle also increases proportionally.

• Layers: lithosphere, asthenosphere, mesosphere, outer core (liquid), inner core ( 

Lab 4:

• When calculating y=mX + B: REMEMBER %. (parts power thousand) → so keep value at 36 not .36

• How salinity works:

• Salinity: the amount of dissolved solids in water. The most common dissolved solid is sodium chloride or table salt.

  • Thus, as salinity and the number of dissolved ions increases so does electrical conductivity.

  • More salt: increases density | less salt: decreases density

  • Conductivity: ability of a material to conduct or transmit heat, electricity, or sound

• Salinity vs. Conductivity:

• When salinity is low, then electrical conductivity is also relatively low

• When salinity is increases then electrical conductivity also increases

• Thus, as salinity and the number of dissolved ions increases so does electrical conductivity

Lab 5:

• Downwelling: due to local surface wears higher density they spontaneous sink and are replaced with surrounding surface waters

  • Changes of water explained: decreased temperature; increased salinity and, in turn, also sink. 

  • downward movement of surface water to deeper layers, typically transporting oxygen but limiting nutrients in deeper waters.

  • Reasoning:

    • Cold Temperatures – Cooler water is denser and sinks.

    • Increased Salinity – Higher salinity makes water heavier, causing it to sink (e.g., from evaporation or sea ice formation).

    • Wind Patterns – Winds pushing surface water toward a coast or converging in the open ocean can force water downward.

• Upwelling: brings waters backs up to the surface through upward entrainment by narrow, deep, and fast western boundary currents, vertical mixing by turbulent flow across spreading ridges and around seamounts/ islands, decreasing density from heat released from the underlying oceanic crust

  • is the rise of cold, nutrient-rich water from the deep ocean to the surface, supporting marine life. 

  • Reasoning:

    • Wind Patterns – Winds push surface water away (often due to the Coriolis effect), allowing deeper water to rise.

    • Coastal Upwelling – Happens when winds blow parallel to coastlines, moving warm surface water away and allowing cold water to rise.

    • Equatorial Upwelling – Trade winds push water apart along the equator, drawing deep water upward.

• Tilt of the earth:

  • Higher latitudes (Polar):

    • Sunlight strikes at lower angles.

    • Less sunlight per unit area.

    • Physically farther from the sun.

  • Lower latitudes (Equatorial):

    • Sunlight strikes at higher angles.

    • More sunlight per unit area.

    • Physically closer to the sun

• Southern Hemisphere vs Northern Hemisphere:

  • Southern hemisphere experiences summer while the northern hemisphere experiences winter: due to the earth rotation and its angle

  • Hotter in summer in southern hemisphere due to angle of earth → North and South are opposite

• Currents:

  • The Coriolis effect causes currents to curve right (clockwise) in the Northern Hemisphere and left in the Southern Hemisphere (counter clockwise).

  • Coriolis effect: the way Earth's rotation makes moving objects, like wind and ocean currents, appear to curve instead of moving in a straight line.

    • earth's rotation moves winds/currents to right in the northern hem

  • Currents occur due to density and thermocline convection (movement of ocean water caused by temperature and density differences, where warm, less dense water rises and cold, denser water sinks within the thermocline layer).

•  Isopycnals: are lines on a graph or ocean profile that connect points of equal density

  • Can’t measure TSD so use observed temp and observed salinity to estimate

• Thermohaline circulation: Deep ocean joint effect of temperature and salinity. 

  • Temperature: Cold water is denser and sinks in polar regions, especially in the North Atlantic.

  • Salinity: Water with higher salinity is also denser and tends to sink. This typically happens in areas where evaporation exceeds precipitation (e.g., the Mediterranean Sea).