The above image is of the steep upper slopes (in excess of 30°) of Mt. Erebus. The composition of the lava flows here are anorthoclase tephriphonolite. Apparent in the right foreground of this image are the channels or flow levees of at least one flow. The length of many of these flow levees is hundreds of meters while the width can be 10's of meters. The plateau observed at top of the image is approximately 5 kilometers across.

This image is a close-up shot of an anorthoclase phonolite lava flow from the summit region of Mt. Erebus. The light gray lathes are anorthoclase feldspar crystals within a matrix of phonolite. Each anorthoclase crystal is approximately 3-6 cm in length. The upper one-third of Mt. Erebus is composed of lava of this composition.