The rocks here are argillaceous schist, red and white.
"The Last Journals of David Livingstone, in Central Africa, from 1865 to His Death, Volume I (of 2), 1866-1868" by David Livingstone
The rock of Righi is composed of pebbles of different kinds, joined by a red argillaceous gluten.
"On the Old Road, Vol. 2 (of 2)" by John Ruskin
It is found in abundance on argillaceous rocks.
"Vegetable Dyes" by Ethel M. Mairet
ARGILLACEOUS ROCKS are rocks in which clay prevails (including shales and slates).
"The New Gresham Encyclopedia. Vol. 1 Part 2" by Various
Argillaceous rocks, 11. schist, 465.
"A Manual of Elementary Geology" by Charles Lyell
The argillaceous, or clay rocks, including muds, clays, and shales.
"The Elements of Geology" by William Harmon Norton