GEOS104 Exam 1 Study Guide

Which direction does the Earth rotate as viewed from the surface in both hemispheres?

Earth rotates from west to east.

If you look down at the Earth from above the North Pole, which way does it rotate? What about from above the South Pole?

North Pole view: counterclockwise; South Pole view: clockwise.

In the northern hemisphere, an object moving straight appears to turn which way due to the Coriolis effect?

Northern hemisphere: straight motion appears to turn to the right.

In the southern hemisphere, an object moving straight appears to turn which way due to the Coriolis effect?

Southern hemisphere: straight motion appears to turn to the left.

Southern hemisphere: straight motion appears to turn to the left.

Northern hemisphere: around a low-pressure system, winds rotate counterclockwise.

How does the Coriolis effect influence surface wind flow around a low-pressure system (cyclone) in the northern hemisphere? Southern hemisphere?

Hadley cell, Ferrel cell, Polar cell.

Name the three main circulation cells in each hemisphere

Hadley cell, Ferrel cell, Polar cell.

At which latitudes does air rise and where does it sink in the Hadley and Ferrel cells?

Air rises: at the equator (ITCZ) and 60° latitude.
Air sinks: around 30° latitude (subtropical highs) and poles.

Which wind cells or zones are most closely associated with desert regions and why?

Deserts are most associated with subtropical high-pressure zones (~30° latitude) because sinking air is dry and suppresses precipitation.

If a hurricane forms in the northern hemisphere, what direction will the winds rotate around its center?

Hurricane rotation in northern hemisphere: counterclockwise.

What is the likely cause of a hurricane’s initial westward motion, and why might it eventually turn or veer off this path?

Initial westward motion: driven by trade winds. Eventual turn: interaction with westerlies and continents steering it.

Explain why the Coriolis effect does not influence water draining in sinks in everyday life.

Coriolis effect doesn’t influence sinks because it’s extremely weak at small scales; other motions (wind, turbulence) dominate.

If surface winds were moving from the pole to the equator, what would be the expected prevailing wind direction in western Pennsylvania? Why is this not what we observe?

If winds moved from pole to equator, western Pennsylvania would see southerly winds. This doesn’t happen because of the Earth’s rotation (Coriolis effect) and multi-cell circulation patterns.

How do factors like friction, continents, and mountains modify the simple single-cell wind pattern?

Factors like friction, continents, and mountains modify simple circulation by slowing winds, redirecting flow, and creating localized pressure systems, producing the three-cell pattern instead of one single cell.

Which features were most difficult to reproduce on a Bath. Map?

• Small obstacles.

• Sharp ridges.

• Narrow trenches.

• Sudden depth changes.

When creating a bathymetric map from limited data points, which method helps improve accuracy?

Increasing the number of measurement points

Which of the following best describes how your bathymetric map should compare to the actual seafloor?

Shows approximate shape and major features

Which feature is typically the most difficult to reproduce on a bathymetric map?

Small obstacles and narrow trenches

When mapping another group’s artificial seafloor, which factor makes the recreation most accurate?

Having more measurement points and close spacing

Which of the following is a likely challenge when recreating a seafloor?

Small obstacles and abrupt depth changes

How do contour lines improve the interpretation of bathymetry?

They fill in unknown points to show seafloor shape

Which statement describes the difference between an exaggerated profile and an unexaggerated one?

Exaggerated profile shows slopes steeper; unexaggerated looks flatter

What relationship was observed between basement rock age and distance from the mid-ocean ridge in DSDP Leg 3?

Basement rocks increase in age with distance from the ridge

What relationship was observed between the age of sediment overlying basement and distance from the ridge?

Sediment age increases with distance from the ridge

Why do sediments overlying basement rocks also increase in age with distance from the ridge?

Sediment forms at the ridge and moves outward with seafloor spreading

How is the rate of seafloor spreading calculated?

Distance ÷ Time

Using the example data (distance = 1079 km, age = 62 million years), what is the average spreading rate?

1.74 cm/yr

What was a key contribution of DSDP Leg 3 to plate tectonics theory?

Providing ground-truth data for seafloor age vs. distance from ridge

Which statement best describes the basement rocks drilled during Leg 3?

They crystallized at the ridge axis and moved outward with seafloor spreading

How did scientific ocean drilling in 1969 compare to 2006?

Fewer sites in 1969; drilling was in its infancy

Why was it important to compare basement rock age and sediment age in the South Atlantic?

To test the seafloor spreading hypothesis

What does a positive correlation between rock age and distance from the ridge indicate?

Rocks form at the ridge and move outward as the seafloor spreads

Sediment accumulates on basaltic basement rocks and moves along with them because:

The sediment is part of the rigid lithosphere

Where are nutrients like nitrate most abundant vertically in the ocean

Below about 400 meters

Why are nitrate and oxygen profiles generally opposite in the ocean?

Primary producers at the surface use nutrients and produce oxygen

What role do primary producers (e.g., phytoplankton) play in creating these patterns?

They use nutrients at the surface and produce oxygen via photosynthesis

In the Northern Hemisphere, Ekman transport moves surface water:

90° to the right of the wind

Areas where ocean currents converge cause:

Downwelling (surface water sinks)

Areas where ocean currents diverge cause:

Upwelling (deep water rises)

Given that nutrients are more abundant at depth, where is primary productivity highest?

In areas of upwelling

Why are the most fish caught in areas of high primary productivity?

High productivity areas provide abundant food for higher trophic levels

If whaling increased in the Ross Sea, what would happen to phytoplankton biomass?

Decrease, because whale predation indirectly reduces phytoplankton

If the penguin population increased, what would likely happen to the elephant seal population?

Decrease due to competition for shared resources

If the fish population decreased, what happens to krill?

Krill population increases (less predation)

If fish populations decrease, what happens to baleen whales?

Decrease due to less prey availability

If glacial meltwater increases, reducing upwelling and nutrient availability, what happens to phytoplankton?

Phytoplankton decrease

How does a decrease in phytoplankton affect the rest of the food web?

Everyone is affected