Pillow Lava - Use As A 'Way-up' Criterion

Use As A 'Way-up' Criterion

Pillow lavas are used as way-up criterion in geology. There are three key ideas that can be used as part of this, and that a pillow lava will show if it is the correct way-up:

1. Vesicles will be found towards the top of a pillow as the gas will be less dense than the surrounding rock.
2. The pillow structures will show a convex upper surface.
3. The pillows will have a tapered base downwards as they have moulded to the underlying pillows during their formation.