Dynamic Planet

UTA 2019

ANSWER KEY

A note to the graders: Please be careful!!! Many of these questions have partial credit -- read
through the entire answer since there might be different numbers of points awarded for different
parts of the answer. I’ve highlighted the places where points can be awarded.

University of Texas at Austin Invitational 2019

Section 1: (18 points)

1. Trade winds (1 pt) push water near the equator towards the west (1 pt). The westerlies (1 pt) push water towards
the east at high latitudes (1 pt).
2. 2 percent (1 pt).
3. The Gulf Stream (1 pt)
4. The Coriolis Force/Effect (1 pt). The “force” comes from the rotation of the Earth about its axis (1 pt).
5. The Coriolis effect (1 pt) deflects objects to the right in the Northern Hemisphere and to the South in the
Southern Hemisphere (1 pt, ½ credit for only mentioning opposite direction).
6. Eastern boundary currents are colder while western are warmer (1 pt). Eastern boundary currents are weaker
while western are stronger (1 pt).
7. Cold core ring current (1 pt) Also accept: Cold core current; ½ credit: ring current.
8. Meanders from the gulf stream break off the stream (1 pt)
9. See image to the right. Criteria: 3 layers (1 pt), Coldest layer on bottom & warmest
on top (1 pt). Colder layers have “bump” at the center (1 pt). Colder layers are visible
at the center of the top (1 pt).

Section 2: (22 points)

1. Wind speed (1 pt), wind duration (how long the wind blows) (1 pt), and fetch (the
distance over water which a wind blows in a single direction) (1 pt).
2. It means that a wave has achieved the maximum size theoretically possible (1 pt) for a wind of a specific speed
duration, and fetch.
3. When many different smaller waves come together, they Constructive Interference:
Can constructively interfere. Their amplitude/heights add to create on
large wave (1 pt)
4. 1/7 (1 pt)
5. A. Decreases (1 pt) B. Constant (1 pt)
C. Increases (1 pt) D. Decreases (1 pt)
6. D (1 pt)
7. E (1 pt)
8. B (1 pt)
9. G (1 pt)
10. A (1 pt) Criteria: 2 waves (1 pt) in phase (1 pt). Amplitude of starting waves
11. C (1 pt) does not matter. Resultant wave in phase (1 pt) and has amplitude
12. F (1 pt) of wave 1 + wave 2 (1 pt).
13. Rogue Wave (1 pt)

Section 3: (19 points)

1. 6 days (1 pt) 2. 10:50 AM the next day (1 pt) 3. 3:25 AM (1 pt)
4. The Pacific Ocean has two amphidromic points → mixed (1 pt), while the Atlantic Ocean has only one
amphidromic point → diurnal/semidiurnal (1 pt).
5. Daily: Rotation of Earth (1 pt) Monthly: Moon’s orbit abt. the Earth (1 pt) Yearly: Earth’s orbit abt. Sun (1 pt)
6. Accept answers in range of 13-16 m (1 pt). Accept anything from list: funnel shape of the bay, resonance, seiche/
seiche waves, depth of the bay (1 pt).
7. Alaska has a funnel shaped shoreline (1 pt). This decreases the tidal wavelength and increases wave
height/amplitude (1 pt).
9. Amphidromic Points (1 pt). They are where the tidal 8.
amplitude is zero (1 pt).
10. Cotidal Lines (1 pt)

Question 8 Criteria: Height is irrelevant. Two high tides with

different amplitude (1 pt), and two low tides with different
amplitude (1 pt), equal and opposite to the first two (when
compared to a middle line, not zero (1 pt). Alternating high and
low tides (1 pt).

Section 4: (21 points)

1. A. Figure 3 (1 pt)
B. Figure 5 (1 pt)
C. Figure 4 (1 pt)
These tools are used for acquiring water samples at a specific depth. (1 pt)
2. The mechanism is a messenger (1 pt). The messenger is sent down a cable and when it reaches the bottle, the
impact tips the bottle upside down (1 pt) and trips a spring-loaded valve at the end, trapping the water sample (1
pt).
3. A. Figure 6 (1 pt) B. Figure 7 (1 pt) C. Figure 8 (1 pt)
Figure 6/Ekman Grab/A uses the same mechanism (1 pt)
Question 4:
9. Messenger (1 pt). Used to trigger sampling in bottles/some grabs (1 pt).
10. Quadrat (1 pt). Used to sample organisms within its perimeter/determine biodiversity (1 pt).
11. Midwater trawl (1 pt). Samples/collects organisms in the water column (1 pt).
12. Plankton Splitter (1 pt). Subdivides plankton samples (1 pt).
13. Secchi disc (1 pt). Used to measure turbidity (1 pt).

Section 5: (18 points)

1. Fig. 14: Stack (1 pt) Fig. 15: Jetty (1 pt) Fig. 16: Wave Cut Platform (1
pt)
Fig. 17: Lagoon (1 pt) Fig. 18: Natural Arch (1 pt) Fig. 19: Tombolo (1 pt)
2. Longshore drift/currents (1 pt), rip currents (1 pt), and upwelling (1 pt).
3. Traction: large material is rolled along the seafloor (1 pt).
Saltation: beach material is bounced along the seafloor (1 pt).
Suspension: material is suspended in the water and carried by the waves (1 pt).
Solution: material is dissolved and carried by water (1 pt).
4. Sand is stored on berms on summer beaches (1 pt). Sand is stored on offshore bars on winter beaches (1 pt).
5. The reef/island begins to sink (1 pt) due to the weight of the coral reef (1 pt) and absence of volcanic island
building effects (1 pt).

Section 6: (22 points)

1. Mid-ocean Ridge (1 pt)
2. Decompression Melting (1 pt).
3. The lines on the map are strike-slip (1 pt) faults (1 pt). They are formed by uneven spreading rates (1 pt) in
different areas of the ridge.
4. Magnetic minerals (1 pt) in molten rock align to Earth’s magnetic field (1 pt) as the magma cools (1 pt). The
Curie Temperature is the temperature above which materials lose their permanent magnetic properties (1 pt).
5. The symmetry on each side of the ridge (1 pt) of age and polarity show that the mid ocean ridge is a spreading
center (1 pt). And thereby tectonically active/part of the system responsible for tectonic plate movement (1 pt).
6. Accept answers between 180 and 200 million years old (1 pt).
7. Black smokers: Iron Sulfide/FeS (1 pt) White Smokers: Ca (Calcium)(1 pt), Ba (Barium)(1 pt), Si (Silicon)(1 pt)
8. A. Green (1 pt) B. Blue (1 pt) C. Red (1 pt) D. Yellow (1 pt)
9. Below 4000 m, the rate of supply of carbonate/calcite is less than the rate of solvation/dissolution of
carbonate/calcite, so no carbonate oozes are found at depth (1 pt).

Section 7: (20 points)

1. A. Seamount (1 pt) B. Guyot (1 pt) Older: B/Guyot (1 pt)
2. Seamount is formed and reaches above sea level (1 pt). Erosion flattens the top of the seamount (1 pt). The sea
floor gradually sinks (1 pt)
3. Continental Shelf, Abyssal Plains, Abyssal Hills, Mid Ocean Ridge (1 pt).
4. As magma rises through the continental crust (1 pt), it becomes increasingly felsic in composition (1 pt) and
volatiles are introduced (1 pt).
5. B. Continental Shelf (1 pt) C. Submarine Canyon (1 pt) D. Continental Slope (1 pt)
E. Abyssal Plain (1 pt) F. Continental Rise (1 pt) G. Deep Sea Fan (1 pt)
6. Submarine Canyon (1 pt). Formed by turbidity currents (1 pt).
7. Shelf Valley (1 pt). Accept: formed by large river emptying, or glacial meltwater (1 pt).

Section 8: (20 points) Note: for graphs, values don’t need to be 100% accurate, allow for some wiggle room
General (award these pts once, if they’re true for all graphs): curves between 0-1000m (1 pt), flat after 2000m (1 pt).
1. Correct shape (3 pts - 1/curve). Correct start value (3 pts - 1/curve), correct end value (3 pts - 1/curve)
2. Low stronger than mid(1 pt). Mid stronger than high (1 pt). Bump on high (1 pt). Start value ±2 (3 pts - 1/curve).
3. Summer curve is stronger than winter (1 pt). Summer starts around 23 (1 pt), Winter starts around 10 (1 pt)

Section 9: (11 points)

1. The subducting plate moves inward/downward (1 pt), and the accretionary wedge springs upward (1 pt). This
displaces the water on top of it (1 pt), causing a tsunami.
2. Correct answer: 193 (1 pt), correct & labeled units (m/s) (1 pt) work: either wrote sqrt(9.8*3800) or sqrt(g*depth)
(1 pt)
3. Since water is very deep, wavelength is very lon, and water displacement is spread over a larger distance (1 pt).
4. Lituya Bay (1 pt)
5. Indonesia (1 pt)
6. Water recedes (1 pt), because water is drawn back into the approaching wave (1 pt).

Section 10: (29 points)

1. 3.5% (1 pt). Cl-, Na+, Ca2+, Mg2+, K+, Sulfate (SO42-) (6 pts -1 pt each)
2. A. Increase (1 pt) B. Increase (1 pt) C. Decrease (1 pt) D. Increase (1 pt)
3. Buffering maintains the seawater’s pH (1 pt). Carbonate/CO32- (1 pt) CO2 + H2O <--> H2CO3 (1 pt).
4. Accept either 200m or 1000m (1 pt). Euphotic/photic zone (1 pt). Shorter wavelength colors such as blue
penetrate further. Accept: blue only, or blue + purple and/or green (1 pt).
5. Oxygen is depleted at moderate depths due to oxygen consumption from bacteria doing cell respiration (1 pt).
Oxygen is present at the surface because it is directly in contact with the atmosphere/experiences direct mixing
through means such as waves (1 pt, accept either). There is Oxygen at depth b/c colder water can hold more
oxygen, and there is less oxygen consuming bacteria at such low depths (1 pt, accept either).
6. Hydrogen Sulfide/H2S (1 pt)
7. Conservative elements have relatively the same concentration vertically and horizontally in the ocean (1 pt).
Scavenged elements are rapidly removed from the ocean into sediments (1 pt).
Conservative: B, Mg, Br, Mo, Ca, Na, C, Cl, Na, Cs, Rb, F, S, K, Tl, Li, U (3 pts -- 1 pt each of three)
Scavenged: Al, Mn, Bi, Pb, Ce, Sn, Co, Te, Hg, Th (3 pts -- 1 pt each of three)

Section 11: (16 points)

1. Temperature (1 pt), Salinity (1 pt)
2. Formation of sea ice (1 pt) makes surrounding water saltier (1 pt). (Also Accept: brine exclusion) The water is
also cold (1 pt) since it’s the Arctic.
3. The Bering Strait (1 pt) is shallow (1 pt). (1 points for ‘Bering Strait’, 1 point for any variation of “ocean floor
between Arctic and Pacific, aka Bering Strait, is shallow and thus ‘traps’ water”)
4. B, A, C (1 pt)
5. It carries heat to the poles (1 pt), thus affecting the rate of ice formation (1 pt). The more ice/snow there is, the
more albedo (1 pt).
6. The North Atlantic Drift (1 pt) (Also accept: Gulf Stream) carries warm water near them (1 pt)
7. When the glaciers ice sheets melted, they created a large freshwater lake. [1 pt for addressing the presence of
freshwater on the continent] If the lake drained into the Atlantic all at once [1 pt for considering this possibility], the
influx of freshwater would have disrupted the normal cycle of circulation (1 pt).

Section 12: Tiebreaker ONLY GRADED IN THE EVENT OF A TIE

Give 1 point for each answer they write that matches what’s in the boxes below

El Niño La Niña
- Higher than normal air pressure in the western pacific - Lower than normal air pressure in the western pacific
- Decreased rainfall in the western pacific - Increased rainfall in the western pacific
- Cool wet summers in SE US - Dry warm summers in SE US
- Warmer PNW and Alaska - Cool PNW and Alaska
- Strong equatorial countercurrent - Wet PNW
- Wet and Warm Equatorial region - Dry and Cool Equatorial region
- Weaker peruvian current - Stronger peruvian current
- Wet Japan - Dry Japan
- Wet N Europe - Wet N Europe
- Decreased air pressure in equatorial region