Skip to content
Skip to main content

About this free course

Download this course

Share this free course

Moons of our Solar System
Moons of our Solar System

Start this free course now. Just create an account and sign in. Enrol and complete the course for a free statement of participation or digital badge if available.

2.9 Crater morphologies

Now explore these final cross-sectional shapes (morphologies) typical of craters of different sizes, and learn about some of the reasons why morphology depends on size.

Bowl-shaped craters
Figure 26 Bowl-shaped craters
  • A – Smallest crater type.
  • B – Depth typically 20% of crater diameter.
  • C – Concave crater floors; made up of rocks melted during the impact and fractured pieces of solid rock.
  • D – Ground beneath the crater floor is heavily fractured due to impact.
  • E – Crater rim is built up by layers of material ejected as the crater formed.
Flat-floor craters
Figure 27 Flat-floor craters
  • A – More mature simple craters.
  • B – Like bowl-shaped craters, but material from crater walls slumps down into the crater, making the floor much flatter.
Central-peak craters
Figure 28 Central-peak craters
  • A – Smallest of the complex crater morphologies.
  • B – Generally flat crater floors, made up of significantly greater proportions of impact-melted rock compared to simple craters, with a peak or cluster of peaks in the centre.
  • C – Peak forms when underlying material rebounds after crater formation, pushing upwards and rising above the crater floor.
Peak-ring craters.
Figure 29 Peak-ring craters.
  • A – Similar to central-peak craters, but the central peak here rebounds and rises so much that it becomes unstable.
  • B – To regain stability, the oversized central peak collapses in on itself, leaving behind a ring of uplifted material surrounding a flat area in the centre.
Multi-ring basin craters.
Figure 30 Multi-ring basin craters.
  • A – The largest craters, associated with only the largest impactors and most energetic impacts. 
  • B – Crater diameters are so large that they contain several concentric rings of uplifted material, i.e. a larger version of peak-ring craters.
  • C – In multi-ring basins, the largest proportion of material excavated by the impact event is melted, pooling in the centre of the basin floor.