GeographyISC Class 11 · Glacial Landforms

Moraines, Outwash Plains, Eskers and Drumlins (ISC Class 11 Geography)

Updated 17 October 2026 · Fact-checked

Glaciers deposit till (unsorted debris dropped by ice) and outwash (sorted material from meltwater). Moraines are ridges or sheets of till: lateral, medial, ground, terminal and recessional. Related forms are outwash plains, eskers (winding sorted ridges), drumlins (oval hills of till) and erratics.

Understand Moraines, Outwash Plains, Eskers and Drumlins

Two kinds of deposit. Till is unsorted and unstratified debris of boulders, gravel and clay dropped directly by ice. Outwash is debris sorted and layered by meltwater streams.

Moraines.
1. Lateral: ridges along the sides of a valley glacier from debris falling off the walls.
2. Medial: a ridge down the middle where two lateral moraines join as glaciers merge.
3. Ground: a sheet of till on the valley floor as the glacier melts back.
4. Terminal (end): a crescent ridge across the valley at the furthest reach of the snout; it can dam a lake.
5. Recessional: ridges behind the terminal moraine marking pauses in retreat.

Related forms.

Outwash plain: gentle plain of sand and gravel spread by meltwater beyond the terminal moraine.
Esker: a long, winding ridge of sorted sand and gravel laid by a stream in a tunnel under the ice.
Drumlin: a smooth egg-shaped hill of till, elongated along the ice flow with a blunt upstream end and a tapered downstream end; groups give basket-of-eggs topography.
Erratic: a boulder carried far and dropped on different rock.

Sequence from head to snout. Cirque and arete at the head, U-shaped trough and hanging valleys in the middle, then moraines and outwash near and beyond the snout.

Retreat. If the snout retreats a measured distance in a known time, rate = distance / time (convert km to m).

Moraines, Outwash Plains, Eskers and Drumlins: key facts

Deposit types: Till: unsorted, dropped by ice | Outwash: sorted, laid by meltwater
Moraines: $L a t er a l ∣ M e d ia l ∣ G r o u n d ∣ T er mina l ∣ R ecess i o na l$
Related forms: Outwash plain
Esker
Drumlin
Erratic
Retreat rate: $R a t e = d i s t an ce / t im e ∣ C o n v er t k m t o m$

How to answer Moraines, Outwash Plains, Eskers and Drumlins questions

Questions are 3 to 4 marks: distinguish, classify or explain a sequence.

1Define till and outwash first.
2Name each moraine with its position.
3Describe shape and origin of esker and drumlin.
4For sums, convert units and divide.

Moraines, Outwash Plains, Eskers and Drumlins in real life

The idea, met in an everyday situation. Answer the question in your own words, then compare with the model answer. The one-line hook is what to remember.

Reading a ridge

Suppose a hiker finds a curved ridge of mixed boulders and clay across a valley, with a small lake held behind it.

Name the landform and the position of the old snout.

Try it first, then show the solutionSolution

A crescent ridge of unsorted material across a valley is a terminal moraine.
The old snout stood along this ridge, which dams the lake.

Answer: Terminal moraine; the snout reached this line.

Memory hook: Last stop of the ice.

Retreat speed

Suppose a snout retreats 1.2 km in 30 years.

Find the retreat rate in m per year.

Try it first, then show the solutionSolution

1.2 km = 1,200 m.
1,200 / 30 = 40 m per year.

Answer: 40 m per year.

Memory hook: Convert, then divide.

Tricks to remember Moraines, Outwash Plains, Eskers and Drumlins

Short memory aids. Say each one aloud once, then use it on a question the same day.

Till is Thrown, outwash is Washed
Till: dumped by ice, mixed; outwash: washed by water, sorted.
Use it when: Deposit types.
Esker snakes, drumlin eggs
Esker winds like a snake; drumlin is egg-shaped.
Use it when: Related forms.

Moraines, Outwash Plains, Eskers and Drumlins: solved examples

Ordered from board level to HOTS. Try each one before you open the solution.

Example 1: Moraine identification · 1 mark · MCQBoard level

A ridge down the centre of a glacier formed by two merging glaciers is a:
(a) lateral moraine
(b) medial moraine
(c) ground moraine
(d) terminal moraine

Try it first, then show the solutionSolution

Where two laterals join.

Answer: (b) Medial moraine.

Example 2: Till and outwash · 2 marks · Short answerBoard level

Define till and outwash in one line each.

Try it first, then show the solutionSolution

Till: unsorted, unstratified debris dropped by ice.
Outwash: debris sorted and layered by meltwater.

Answer: Till is unsorted ice-deposited debris; outwash is sorted meltwater deposit.

Example 3: Esker and drumlin · 4 marks · Long answerHarder board level

Distinguish between an esker and a drumlin on shape, material and origin.

Try it first, then show the solutionSolution

Esker: a long, winding ridge; drumlin: smooth oval hill.
Esker: sorted sand and gravel; drumlin: till.
Esker: laid by a stream in a tunnel beneath the ice; drumlin: shaped by moving ice, elongated along its flow.
Drumlins often occur in groups.

Answer: Esker: winding sorted ridge made by a subglacial stream; drumlin: egg-shaped till hill moulded by ice.

Example 4: Retreat calculation · 4 marks · Long answerHarder board level

A glacier snout is at a terminal moraine and retreats 1.8 km over 45 years, leaving recessional moraines. Find the average retreat rate in m a year and the number of years to retreat 3 km at this rate.

Try it first, then show the solutionSolution

1.8 km = 1,800 m; rate = 1,800 / 45 = 40 m per year.
3 km = 3,000 m; time = 3,000 / 40 = 75 years.
Recessional moraines mark pauses in this retreat.
The rate is an average; actual retreat varies.

Answer: 40 m per year; 75 years.

Example 5: Valley story · 5 marks · Case-basedHOTS / competency

Case: A survey finds a crescent ridge of mixed debris across a valley, a sheet of till on the valley floor behind it and a gently sloping plain of sand and gravel beyond it. (a) Name each deposit. (b) Say which was laid by meltwater. (c) Explain how a lateral moraine forms.

Try it first, then show the solutionSolution

(a) Terminal moraine (the ridge), ground moraine (the till sheet) and outwash plain (sand and gravel).
(b) The outwash plain.
(c) Debris falls from the valley walls onto the glacier edges and is carried as ridges along the sides.

Answer: (a) Terminal moraine, ground moraine, outwash plain (b) outwash plain (c) wall debris along the sides.

Where students lose marks in Moraines, Outwash Plains, Eskers and Drumlins

The slips examiners see most often, and what to write instead.

Mistake: Calling outwash unsorted
Till and outwash are swapped.
Do this: Outwash is sorted; till is not.
Usually costs: 1 mark.
Mistake: Placing moraines at the snout wrongly
Lateral and terminal confused.
Wrong working
Lateral moraine at the front
Right working
Terminal moraine at the front
Do this: Lateral: sides; terminal: across the valley at the snout.
Usually costs: 1 mark.
Mistake: Retreat unit slip
km and m mixed.
Do this: Convert km to m before dividing.
Usually costs: 1 mark.

Exam tips

Define till and outwash first.
List moraines by position.
Mention direction of flow with drumlins.
Use sketches in words for esker and drumlin.

Practice questions on Moraines, Outwash Plains, Eskers and Drumlins

Write each answer on paper first. Open the hint only if you are stuck, and the answer only when you have finished.

Q1 · 1 mark · MCQBoard level
Boulders carried far and dropped on different rock are called:
(a) erratics
(b) drumlins
(c) eskers
(d) aretes
Hint
Foreign boulders.
Answer
(a) Erratics.
Q2 · 3 marks · Short answerHarder board level
Compare terminal and ground moraines.
Hint
Ridge versus sheet.
Answer
A terminal moraine is a crescent ridge across the valley at the snout's furthest point; a ground moraine is a sheet of till spread over the valley floor as the glacier melts back.
Q3 · 3 marks · Short answerHarder board level
A snout retreats 900 m in 20 years. Find the rate and the retreat in 50 years at this rate.
Hint
Distance over time.
Answer
900 / 20 = 45 m per year; in 50 years 45 x 50 = 2,250 m.
Q4 · 4 marks · Long answerHarder board level
Explain why till is unsorted but outwash is sorted.
Hint
Ice versus water.
Answer
Ice carries and drops boulders, gravel and clay together without sorting. Meltwater streams sort by velocity, laying coarse and fine material in layers.
Q5 · 4 marks · Case-basedHOTS / competency
Case: A farmer finds a field of smooth oval hills all pointing in one direction. (a) Name the landform. (b) Give the direction clue it gives about the glacier. (c) Name the material.
Hint
Elongated with the flow.
Answer
(a) Drumlins. (b) The long axes show the direction of ice flow, with a blunt upstream end. (c) Till.

Test your recall

Answer in your head or on paper first, then open the card. Pulling an answer out of memory makes it stick far better than re-reading.

1.Moraine across the valley?Show answer
Terminal moraine.
2.Sorted tunnel deposit?Show answer
Esker.
3.Egg-shaped till hills?Show answer
Drumlins.
4.Dropped boulders on different rock?Show answer
Erratics.
5.Plain of sand and gravel beyond the moraine?Show answer
Outwash plain.

Moraines, Outwash Plains, Eskers and Drumlins: frequently asked questions

Is outwash glacial?

It is glacial in origin but sorted by meltwater.

What is a recessional moraine?

A ridge marking a pause in retreat.

Do drumlins occur alone?

Often in groups.