G. Cotter, after considering all arguments pro and con, said he favored a pre-Cambrian age for the Salt Range Formation. But before his paper expressing this view went to press (in 1931) Cotter examined occurrences of nummulites, fossil formanifera typical of the Tertiary, discovered by E.R. Gee in the salt marl at Khewra. Cotter, who had originally thought they had been washed into the Salt Range Formation from younger deposits, decided they were native to the Salt Range Formation. In a footnote added to his paper before publication, Cotter reversed the position stated in the paper and declared the Salt Range Formation to be Tertiary. But he regarded it as intrusive, which would explain its position beneath the Cambrian Purple Sandstone. According to Cotter, the plastic salt, of Eocene age, was somehow squeezed by geological pressure and other forces into an abnormal position.