Note 74 — Chapter XI · DESCRIPTION OF THE GEOLOGICAL AND GENERAL PHYSICAL FEATURES (continued)
Reading edition
Both these rocks belong to the hypersthene-augite andesites, showing phenocrysts of both monoclinic and rhombic pyroxene. The first belongs to the orthophyric order described on p. 290; whilst the second belongs to the second order (genus 13, p. 287) where the felspars of the groundmass are lathe-like and in flow arrangement.