C893 Geology II: Earth Systems, catalog number GEOS 5103, is the three-CU earth systems course in the WGU School of Education, covering the geosphere, atmosphere, hydrosphere and biosphere and their dynamic equilibrium over geologic time. Where physical geology asks what things are made of and how they form, this course asks how four systems exchange matter and energy with one another and stay in a moving balance. The assessed skill is systems reasoning, and it is genuinely different from the reasoning in a single-discipline course.
Interaction between systems is the whole subject
The four spheres are a convenient division, not four separate topics. Almost nothing interesting happens inside one of them. Rock weathering is a geosphere process driven by atmospheric gases and water, which consumes carbon dioxide and therefore feeds back into climate. Ocean chemistry is set partly by what rivers deliver from continents and partly by what organisms remove. Life alters the atmosphere, and has done so drastically at least once in a way that changed the planet permanently. A submission that treats the spheres as chapters has not engaged the course.
Dynamic equilibrium is the second idea and the harder one. A system in dynamic equilibrium is not static; it has flows running through it that happen to balance, and that balance can shift when a flow changes. Students who picture equilibrium as stillness cannot explain why a small persistent change in one flux can move a system to a different state. Reservoir and flux thinking, with residence times attached, is the tool that makes this tractable and it is worth learning explicitly.
The biosphere is the sphere most often treated as a passenger, and treating it that way is a content error. Life is a geological force. Photosynthetic organisms changed atmospheric composition permanently, marine organisms build carbonate that becomes rock and locks away carbon for hundreds of millions of years, and root systems accelerate the chemical breakdown of the rock they grow through. A submission that has the biosphere responding to the other three, and never acting on them, has described a one-way system where the course is asking about a coupled one.
The geologic time dimension is the third demand. Systems that appear stable on a human timescale have moved enormously over the planet's history, and the record of those movements is what allows current changes to be assessed against a baseline. Explanations without a timescale attached tend to be either alarming or reassuring for no defensible reason, and reviewers in a science teaching programme are alert to both.
Turning scored aspects into a plan
The scoring detail is inside your Course of Study rather than in the public catalog. Read it before planning, because a School of Education science course may be measured by a submitted performance assessment, by a proctored objective assessment, or by both.
Under a performance assessment, each aspect is scored independently on a three-point scale and a 2 in each aspect passes the task, with no averaging. Head each section with the rubric's own noun so the evaluator scores by reading straight through what is inevitably a long interconnected argument.
The word budget, worked. Assume six scored aspects and directions asking for around 2,000 words. Reserve 160 for framing and 130 for a close, leaving 1,710, about 285 words per aspect. In systems work, budget 70 words for the reservoirs and fluxes involved, 110 for the interaction mechanism, 60 for the timescale, and 45 for the evidence. Aspects that return are usually the ones describing a single sphere without ever naming the exchange with another, because the exchange is what the course is about.
Draw the system before writing about it. A quick reservoir and arrow sketch, even one that never appears in the submission, prevents the most common structural failure, which is an explanation that leaves a flux dangling with no source or sink.
A structure that fits an earth systems response
Task directions govern where they specify a shape. Where they do not, this arrangement makes system interactions explicit rather than implied.
| Section | What belongs in it | How it gets scored |
|---|---|---|
| Reservoirs | Where the material or energy is stored, with sizes where known | Frames the analysis quantitatively rather than descriptively |
| Fluxes | The transfers between reservoirs, with rates and directions | Scored as the core of systems reasoning; missing fluxes break the account |
| Cross-sphere interaction | Which spheres exchange and by what mechanism | The central scored element in this course |
| Feedback | Whether a change amplifies or dampens itself, and why | Scored where system behaviour is named; feedback direction is often mistaken |
| Timescale | Residence times and the period over which the system responds | Scored where geologic time is named and usually vague in drafts |
| Evidence | The record establishing past states: cores, isotopes, sediments, instrument series | Scored where scientific reasoning is named |
| Sources | Survey and agency data, peer-reviewed work, APA formatted | Scored wherever citation is named |
Get feedback direction right, because it is the single most consequential technical detail in systems work. A positive feedback amplifies a change and a negative feedback opposes it, and the words carry no judgement about whether the outcome is good. Students and drafts confuse the two constantly.
Evidence craft in earth systems work
Earth systems science reconstructs past states from proxies, and understanding what a proxy can and cannot say is the core professional skill.
- Name the proxy and what it measures. An isotope ratio, a pollen assemblage or a sediment layer records something specific, and that specificity is the evidence.
- State resolution. A record with thousand-year resolution cannot speak to a decadal change, and mismatched resolution is a common reasoning error.
- Attach numbers to reservoirs and fluxes wherever published values exist, with the source.
- Use agency and survey datasets rather than general web summaries, cited with series and access details.
- Distinguish observed change from modelled projection, and give the method behind any projection you cite.
- Keep quotation minimal; standard descriptions of the carbon and water cycles are heavily reproduced and WGU runs submissions through a similarity check.
The habit that most improves systems writing is naming the residence time. Knowing roughly how long a molecule stays in a reservoir tells you immediately how fast that part of the system can respond, and it turns vague statements about slow or fast change into quantified reasoning a student could check.
What separates Competent from a return
Work is recorded as Competent or Not Competent, with no letter grades and no ordinary grade point average. Because each aspect is scored alone, returns are usually specific.
- Every scored aspect has a heading in the rubric's own words.
- Every process names the spheres exchanging material or energy.
- Every flux has a direction and, where possible, a rate.
- Every feedback is correctly identified as amplifying or opposing.
- Every claim about past states names the proxy and its resolution.
Performance assessment work can be revised and resubmitted with no grade penalty, so a return costs time rather than standing. In a six-month flat-rate term, closing more courses is the only lever on effective cost per course, and systems courses are easy to leave open because the writing feels endless without a structure.
Where a proctored objective assessment applies, the boundary is absolute. Proctored assessments are yours to sit. We prepare with systems diagramming practice, drilled cycles and an honest readiness verdict, and we never ask for portal credentials.
Six mistakes students make in C893
- Writing four separate sphere essays. The exchanges between spheres are the course, and a submission organised by sphere usually never reaches them.
- Picturing equilibrium as stillness. Dynamic equilibrium means balanced flows, and only that picture explains how a system shifts state.
- Reversing feedback direction. Positive amplifies, negative opposes, and the mistake inverts the entire prediction.
- Leaving fluxes unquantified. A cycle drawn without rates cannot support any claim about how fast anything responds.
- Ignoring proxy resolution. Using a coarse record to argue about a fine-scale change is a reasoning error reviewers catch quickly.
- Dropping geologic time. The long record is the baseline against which any current change has to be assessed.
- Treating the biosphere as a passenger. Life has altered the atmosphere and built rock, and a coupled system has to be written as coupled.
How support works on this course
Send your Course of Study for C893 with any rubric and task directions. What comes back is a reservoir and flux map of the system your task concerns, a feedback direction check across the whole draft, residence times and rates sourced from published data, and an aspect-mapped draft where every process names the spheres it connects.
Where a proctored component applies, the preparation becomes cycle drills: carbon, water, nitrogen and rock cycles reconstructed from memory as reservoirs and arrows, since that reconstruction is what the harder items actually test.
Systems thinking is the transferable part of this course. Once reservoirs, fluxes, feedbacks and residence times are habitual, the same structure explains climate, water supply, nutrient pollution and half the environmental questions a science teacher will be asked.
Questions students ask about C893
Is C893 the same course as GEOS 5103?
How is C893 different from Geology I?
Can you take my proctored assessment?
Writing four sphere essays instead of one system?
Send your Course of Study and any rubric. You get a reservoir and flux map, a feedback direction check, sourced rates and residence times, and aspect-mapped drafting.
Where C893 sits in WGU's programs
The July 2026 catalog places this code in 1 current WGU program. Open a program page for the complete standard path and term positions. The live Degree Plan remains authoritative after transfer credit, substitutions, and mentor planning.
The assessments, one by one
The public catalog does not publish this course's PA/OA identity or task count. WGU Tutors publishes at most one PA manual per course and only from a WGU-controlled public rubric. Until that source exists, PA help begins from the student's real Course of Study and OA support remains preparation only.