Note 10 — Chapter IX
Reading edition
For an interesting and valuable account of these Gruinard rocks and their correlations, by the greatest authority, Professor Judd, see Quart. Jour. Geolog. Soc. for 1878, pp. 670, 671, 688-690, where they are called Poikilitic, or Variegated, their varied colouring being well shewn on Loch Gruinard.