Note 76 — Chapter XI · DESCRIPTION OF THE GEOLOGICAL AND GENERAL PHYSICAL FEATURES (continued)

Both the types are referred to genus 1 of the augite-andesites, the olivine, when present, being quite insufficient to give a character to the rock. They however belong to different species according to the length of the felspar-lathes, which in the doleritic rocks averages ·2 mm. and in the other type ·08 mm.