| How might mudcracks be preserved in rock? Crossbedding? Shell impressions? | HINT: Review how ripplemarks are preserved. |
| Would the presence of such features serve to distinguish between sedimentary and volcanic layers? | HINT: How likely do you think it is that mud, sand and shells would survive immersion in lava? |
| Look at the two pictures under 'Useful Structures' that show mudcracks. Is the origin of mudcracks similar to the origin of columnar jointing? Explain. | Hint: Mudcracks form due to shrinkage, but the shrinkage in NOT due to cooling. What might be lost from mud to cause shrinkage? |
| Can columnar jointing be used to identify volcanic layers in the absence of volcanic cones? | HINT: Does any other type of layering contain a feature similar to columnar jointing with which it could be confused? |
| Both mudcracks and lava that has undergone columnar jointing both have networks of fractures. How might mudcracks and lava flows be distinguished? | HINT: What differences might there be between dried mud and solidified lava? Think texture. Think composition. |