where watercolour dilutes transparent colour, chalk pastel lays it on thick and opaque. Leighton appears to have toyed with the medium from time to time throughout his career, using it in conjunction with watercolour to produce sketches on the spot. His pastels fall into two groups, probably relating to his early and late periods: (1) large, highly finished works on light paper, and (2) small renderings on dark paper. Group (1) is most likely from 1925-35, while the spare suggestion of the latter group points to the '40s, '50s, and '60s. The latter pictures gain expression from colour in a new way and raise a basic question: did Leighton plan to follow them up in oils? The extreme stylization of a pastel of a Mountain Peak (Cat. #39) may be a study for his work in oils and shows Leighton nodding in the direction of abstraction. Perhaps it was done around the same time as the large, stylized painting of Mount Hungabee (Cat. #15). It certainly dates from his second phase.