Ausgeology. Years 3 to 10 lessons

Year 8 Geography · AC9HG8K01 · AC9HG8K03 · AC9HG8K04

Nitmiluk Gorge: landforms and landscapes.

In the Northern Territory, the Katherine River has cut a chain of 13 gorges through a plateau of sandstone. On this virtual field trip you will visit five sites, collect evidence in your field notebook and use it to answer one big question.

Illustration
A block of the plateau, cut open at the front to show what lies underneath: flat layers of sandstone, joints (cracks) in two directions, and the zigzag gorge with the river at the bottom. Not to scale.

Our inquiry questionHow did Nitmiluk Gorge form, and how should it be cared for?

Nitmiluk is Jawoyn Country. Nitmiluk (say Nit-me-look) is the Jawoyn name for Katherine Gorge. It means Cicada Place. The national park is owned by the Jawoyn people and managed by the Northern Territory Parks and Wildlife Commission under a 99-year lease, in association with Jawoyn people, culture and traditions.

Everything this lesson says about Jawoyn culture comes from what Jawoyn people have chosen to share publicly.

The field trip

  1. Site 1The lookoutName the landforms you can see.
  2. Site 2From aboveMeasure the zigzags and find out why.
  3. Site 3In the gorgeRaise a flood and watch what it moves.
  4. Site 4RapidsSort the evidence by process.
  5. Site 5CountryLearn what the gorge means to Jawoyn people.

Learning intention

We are learning how natural processes shaped Nitmiluk Gorge, why the gorge matters to different people, and how it could be cared for.

Success criteria

  • 1I can identify and describe the main landforms of Nitmiluk Gorge.
  • 2I can explain how weathering, erosion, rockfall and deposition formed the gorge and keep changing it.
  • 3I can use rainfall and flood data to explain when the river does most of its work.
  • 4I can explain how Nitmiluk is valued as Jawoyn Country.
  • 5I can weigh environmental, economic, social and cultural factors to suggest how the gorge should be cared for.

Australian Curriculum v9, Geography: AC9HG8K01 “geomorphological processes that produce different landscapes and significant landforms”; AC9HG8K03 “the spiritual, aesthetic and cultural value of landscapes and landforms for people, including Country/Place of First Nations Australians”; AC9HG8K04 “the interconnections between human activity and geomorphological processes, and ways of managing distinctive landscapes”

Printable activity

Field sketch

Draw an annotated field sketch of a landscape: the lookout view from this lesson, or a place near your school. The same links are at the end of the lesson.

Activity sheet (PDF) Editable (Word)

How it works

  1. Ask questions that the field trip could answer.
  2. Visit five field sites. Each one has something to do and a box in your field notebook.
  3. Analyse rainfall and flood data for Katherine.
  4. Decide how the gorge should be cared for, and justify your choice.
  5. Report. Your notes build a field report that you can copy or print.

Your notes and answers are saved in this browser, so you can stop and come back later.

Step 2 · Ask questions

Ask good questions.

A geographical inquiry starts with questions that evidence can answer: what a place is like, how it formed and is changing, and how people value and care for it.

Our inquiry questionHow did Nitmiluk Gorge form, and how should it be cared for?

Which questions would help?

Choose all that fit

Choose every question that would help answer our inquiry question. Then check your choices.

Field notebook: my questions

Write three questions of your own. You will come back to them at the end.

Step 3 · Site 1 · The lookout

Look along the gorge.

From a lookout on the plateau you can see straight down the gorge. Start by naming what you see. Each landform is part of the landscape.

Label the landforms

Site 1
Illustration

Choose a label, then the numbered place it belongs.

Field notebook: Site 1

Use at least three of these words.

Step 4 · Site 2 · From above

Why the zigzags?

From the air the gorge is not a smooth curve. It runs straight, turns sharply, runs straight again and turns back. Measure four of the bends, then look for the cause.

Measure the bends

Site 2

Choose each numbered bend to measure the angle between the two straight reaches of the river.

BendAngle
1–
2–
3–
4–

The bends in the gorge are all close to 90°. What does this tell you?

Cut the gorge

3D model
Long ago Today

Model, not to scale. The joints are drawn much further apart than real ones. The sandstone is very old: it was laid down as sand more than 1600 million years ago. Cutting the gorge took a very long time, and geologists still debate how long.

Field notebook: Site 2

Use the words joint, river and erosion.

Step 5 · Site 3 · In the gorge

Raise a flood.

Down at river level the cliffs tower above you. In the dry season the river is calm. In the wet season it can rise many metres up the walls. See what the water can move.

The river through the seasons

Site 3
Model
Dry Big flood

Try this: raise the river to a big flood, then lower it again. Watch the hollow in the wall.

Real floods at the Katherine bridge

The gauge is on the Katherine River at the Katherine bridge, about 30 km downstream of the gorge.

Key idea

A river does most of its cutting during floods.

Fast, deep water rolls pebbles and even boulders along the bed. They grind the rock away, which is called abrasion. Where the water slows down, it drops what it carries. A slackwater deposit left in a sheltered spot shows how high a flood reached.

When does the river cut down into its bed fastest?

Geologists find a layer of river sand in a sheltered hollow high on the gorge wall. What does it tell them?

Field notebook: Site 3

Say what the water carries, what that does to the riverbed, and what floods leave behind.

Step 6 · Site 4 · Rapids and boulders

Read the evidence.

Between the gorges the river tumbles over bars of rock and boulders. Here you can find evidence of all four processes that shape the gorge: weathering, erosion, rockfall and deposition.

Which process made it?

Site 4
Illustration

Which process made it?

Your sorted evidence

Field notebook: Site 4

Think about where each process happens: on the riverbed, or on the walls.

Step 7 · Site 5 · Country

Nitmiluk is Country.

For Jawoyn people, the gorge is part of their Country, where they have kept their culture and traditions for thousands of years. Here is some of what Jawoyn people share publicly about Nitmiluk.

Illustration
Deep green water between the cliffs of a gorge, seen from a boat.

The Second Gorge

By tradition, Bolung, the Rainbow Serpent, lives in the deep green pools of the Second Gorge.

“Bolung must not be spoken to and must be left undisturbed.”Jawoyn people, on the Nitmiluk Tours website. Nitmiluk Tours is part of the Jawoyn Association.

Jawoyn people do not fish in the pools where Bolung sits. Drinking water is taken from the shallow water nearby, not from the deep pools. Visitors are asked not to fish in the Second Gorge.

  • The nameNitmiluk (say Nit-me-look) means Cicada Place. Jawoyn people tell how Nabilil, a figure from the Creation Time, named the gorge after hearing a cicada’s call there.
  • The ownersThe park was handed back to its Traditional Owners, the Jawoyn people, in 1989. They lease it to the Northern Territory Parks and Wildlife Commission for 99 years, and it is managed in association with Jawoyn people, culture and traditions.
  • Rock artJawoyn rock art sites are found across the park. Visitors may look, but must not touch.
  • Not sharedSome places and stories are not shared publicly. That is the Jawoyn people’s choice, and a good geographer respects it.

Why do Jawoyn people not fish in the deep pools of the Second Gorge?

Field notebook: Site 5

Values can be spiritual, cultural, aesthetic (its beauty) or economic.

Step 8 · Analyse

When does the river work?

The river changes the gorge most during floods. So when are floods most likely? Use the rainfall data for Katherine to find out.

Average rainfall each month at Katherine

Data

Hover over or tap a month to read its rainfall, or select the chart and use the arrow keys. The chart starts in July so the whole wet season sits together in the middle.

Rainfall: Bureau of Meteorology, Katherine Aviation Museum (station 014903), monthly averages from records between 1943 and 2020. Floods: Northern Territory Government and news reports.

Which month has the most rain, on average?

About how much of the year’s rain falls in the wet season, from November to April?

All three biggest floods came in January, March or April. What best explains this?

Field notebook: analysis

Use at least two numbers from the chart or table.

Step 9 · Decide

Care for the gorge.

Many people want to visit Nitmiluk. How could the gorge be cared for while people still enjoy it? Weigh up three options, then choose one and justify it.

A made-up scenario

The park’s managers can fund one new project for visitors. Which one should it be?

This scenario is made up for practice. In real life, decisions about the park are made with Jawoyn Traditional Owners under joint management, and only Jawoyn people can say how their Country should be cared for. A strong plan says how they would be involved.

Weigh up the options

Four factors

For each option, decide whether it helps, has a mixed effect or harms each factor. Open “Things to think about” for ideas. There is no single right answer.

Field notebook: my decision

Which option do you choose?

Use at least two factors, and say what your choice gives up compared with the other options.

Check your decision

Step 10 · Report

Your field report.

Your notes have built a field report. Finish it with a conclusion, then check what you have learnt.

Field notebook: conclusion

Use evidence from at least three sites, and the rainfall data.

Field report: Nitmiluk Gorge

Exit check

One try for each question. Your results show which parts of the lesson to look at again.

Which sequence best explains how Nitmiluk Gorge formed?

Which process makes the gorge deeper?

A student says: “The river does most of its work in just a few months each year.” Which evidence supports this best?

Which action shows respect for Nitmiluk as Jawoyn Country?

Which plan for the gorge is best justified?

Offline activity

Field sketch

Draw an annotated field sketch of a landscape: the lookout view from this lesson, or a place near your school. Label the landforms and add notes about the processes that shaped them.

Activity sheet (PDF) Editable (Word)
For teachers

Curriculum

Australian Curriculum: Humanities and Social Sciences, Version 9. Year 8 Geography, Landforms and landscapes.

AC9HG8K01: geomorphological processes that produce different landscapes and significant landforms
AC9HG8K03: the spiritual, aesthetic and cultural value of landscapes and landforms for people, including Country/Place of First Nations Australians
AC9HG8K04: the interconnections between human activity and geomorphological processes, and ways of managing distinctive landscapes

The lesson also works through the Year 8 geography skills, AC9HG8S01 to AC9HG8S06: developing questions, collecting and representing information (including from fieldwork), interpreting and analysing data, drawing conclusions and proposing action, and communicating findings.

How the lesson is taught

The lesson is a geographical inquiry, run as a virtual field trip.

  • Ask (screen 2): students judge which questions evidence could answer, then write three of their own.
  • Collect (screens 3 to 7): five field sites, each with an interactive, a check for understanding where it helps, and a field notebook entry.
  • Analyse (screen 8): Bureau of Meteorology rainfall data for Katherine, linked to the three biggest floods on record.
  • Decide (screen 9): a made-up management scenario weighed against environmental, economic, social and cultural factors.
  • Communicate (screen 10): the notebook entries build a field report, finished with a conclusion. A five-question exit check is mapped to the success criteria.

Allow two to three lessons: Start to Site 2, then Sites 3 to 5, then Analyse to the report. The field sketch suits homework or a lesson outside in the school grounds.

About the models and data

  • The lookout view, the block diagram, the field sketches and the route map are simplified illustrations. Real bends in the gorge are close to right angles but not exact.
  • The flood model shows the lower 35 m of the gorge wall. Studies of the gorge report wet season rises of up to about 18 m. The hollow in the model stands for any sheltered spot: Baker and Pickup (1987) found most slackwater deposits in Katherine Gorge at the mouths of side streams.
  • Published ages for the Kombolgie sandstone range from about 1650 to more than 1800 million years, so the lesson says “more than 1600 million years”. How long the gorge took to form is still debated, so no figure is given.
  • Flood heights are for the gauge at the Katherine bridge, about 30 km downstream: about 20.4 m in late January 1998 (the record, after Cyclone Les), just below 19 m on 6 April 2006, and 19.2 m in March 2026, the second highest on record.
  • The Bureau of Meteorology’s yearly average for the station (1142.6 mm) comes from fewer complete years than the monthly averages, so it does not equal the sum of the months. Students should work with the monthly figures.

Jawoyn culture in this lesson

  • Cultural information comes only from what Jawoyn people share publicly: the Nitmiluk Tours website (Nitmiluk Tours is part of the Jawoyn Association) and Northern Territory Government park information.
  • The lesson does not depict Bolung or retell Jawoyn stories beyond what is published.
  • If you can, invite a local Aboriginal speaker to talk about Country where you live, and acknowledge the Traditional Owners of your own area.

Answers at a glance

  • Site 2: all four bends measure close to 90°, because the river follows two joint sets at right angles.
  • Site 4: river erosion (potholes, undercut wall), weathering (crumbling face, roots in a crack), rockfall (fallen blocks, fresh scar), deposition (sand bank, sand high on the wall). River erosion deepens the gorge; weathering and rockfall widen it.
  • Decide: there is no single right option. Look for a named choice, at least two factors, a trade-off, and how Jawoyn Traditional Owners would be involved.

Saved progress

Answers and notes are saved only in this browser on this device. Nothing is sent anywhere.

Sources

Glossary