C893 looks at Earth as one connected system: rock, air, water and life constantly exchanging energy and matter over geological time.
WGU describes it as an examination of the geosphere, atmosphere, hydrosphere and biosphere and the dynamic equilibrium of these systems over geologic time, for graduate students seeking licensure or endorsement, or an M.A., in secondary science education.
It also examines the history of Earth and its lifeforms, with an emphasis on meteorology. WGU lists Geology I: Physical as the prerequisite.
The difficulty is connection. Students often learn each sphere separately; assessments ask how a change in one ripples through the others.
Course at a Glance
| Item | Details |
|---|---|
| University | Western Governors University (WGU) |
| Course code | C893 |
| Level | Graduate, competency-based |
| Program | M.A. Science Education (Secondary Earth Science) |
| Prerequisite | Geology I: Physical |
| Typical work | Written explanation or exam; check your course page |
What C893 Covers
| Area | Key ideas |
|---|---|
| Geosphere | Rock cycle, plate tectonics, weathering and erosion |
| Atmosphere | Layers, composition, energy balance, weather and climate |
| Hydrosphere | Water cycle, oceans, groundwater, ice |
| Biosphere | Life's effects on Earth's systems |
| Dynamic equilibrium | Feedbacks that stabilize or destabilize systems |
| Earth history | Geologic time, fossils and the history of life |
| Meteorology | Air pressure, fronts, storms and forecasting |
Key Concepts Explained
Spheres Interact
Every major Earth process involves more than one sphere. Volcanic eruptions (geosphere) release gases and ash into the atmosphere, which can cool climate, alter precipitation (hydrosphere) and affect ecosystems (biosphere).
Example: Chemical weathering of silicate rocks consumes carbon dioxide from the atmosphere. The products wash into the oceans, where organisms use them to build shells that eventually form limestone. Over millions of years, this cycle helps regulate atmospheric CO2 and global temperature.
Feedbacks and Dynamic Equilibrium
Negative feedbacks stabilize a system; positive feedbacks amplify change. Dynamic equilibrium means a system is constantly changing but stays balanced overall until a large disturbance pushes it to a new state.
Example: Ice-albedo feedback is positive. Warming melts reflective ice, exposing darker land or ocean that absorbs more sunlight, causing further warming.
Air Masses and Fronts
Weather changes when air masses with different temperature and moisture meet. At a cold front, dense cold air pushes under warm air, forcing it up quickly and often producing thunderstorms. At a warm front, warm air rises gently over cold air, giving wider areas of steady rain.
Geologic Time and the History of Life
Relative dating orders events using principles such as superposition (younger layers on top) and cross-cutting relationships. Absolute dating uses radioactive decay to assign ages in years. Together they build the geologic time scale, divided into eons, eras and periods, often marked by major changes in life.
Example: Photosynthetic microbes released oxygen for hundreds of millions of years until it began to build up in the atmosphere. This change in the atmosphere, caused by the biosphere, made possible the later evolution of complex, oxygen-breathing life: a clear case of spheres shaping each other over geologic time.
Meteorology Essentials
Because the course emphasizes meteorology, expect weather to feature strongly. Core ideas include:
- Uneven heating of Earth's surface drives pressure differences and wind.
- Air pressure: air flows from high to low pressure; the Coriolis effect deflects it.
- Humidity and condensation: rising air cools, reaches its dew point and forms clouds.
- Storms: thunderstorms, mid-latitude cyclones and hurricanes each need specific conditions.
- Weather versus climate: short-term conditions versus long-term patterns.
Reading a surface weather map (isobars, fronts, pressure centers) and predicting the next day's weather is a practical skill worth practicing.
Typical Tasks and How to Approach Them
| Task type | What it tests | How to approach it |
|---|---|---|
| System interaction | Linking spheres | Trace a change through at least two spheres |
| Weather map analysis | Meteorology skills | Identify fronts and pressure, then predict |
| Earth history | Geologic time | Use relative and absolute dating correctly |
| Feedback explanation | Equilibrium | State whether it stabilizes or amplifies |
Where Students Get Stuck
- Isolated spheres. Always ask what the other spheres are doing.
- Feedback direction. "Positive" does not mean good; it means amplifying.
- Fronts. Mixing up cold and warm front weather is common.
- Time scales. Distinguish processes taking days, centuries and millions of years.
Study Tips for C893
- Draw a four-sphere diagram and add arrows for each process you learn.
- Practice reading real weather maps daily for a week.
- Build a geologic time scale with major events and life forms.
- Review Geology I material on rocks and plate tectonics first.
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Frequently Asked Questions
WGU lists Geology I: Physical as the prerequisite.
The geosphere, atmosphere, hydrosphere and biosphere, their dynamic equilibrium over geologic time, Earth history and its lifeforms, with an emphasis on meteorology.
A state where processes constantly move energy and matter, but the system stays broadly balanced until a large change shifts it.
WGU's description says the course emphasizes meteorology, so expect weather processes and maps to feature strongly.
No. We never take exams or log in for students. We provide explanations and study notes.
No. We are independent and not connected with Western Governors University.