C. K. Leith, in his address last year as retiring President of the Geological Society, adverted briefly to the theories which have been put forward to explain the general absence of fossils from pre-Cambrian strata. Since the mystery which veils the early eons of the history of life has intrigued both geologists and paleontologists, I have ventured to make it the subject of my address. I have no new facts to offer; my only contribution will be on the theoretical side.
Ever since Sir William Logan demonstrated that the Cambrian rocks are not the oldest sediments, but that they are underlain by vast thicknesses of water-laid strata, geologists and paleontologists have been searching for evidences of the “Primordial Fauna.” Many of the pre-Cambrian strata are limestones and shales which appear to be little altered, in spite of their incomprehensible age; hence, they present a constant challenge to the investigator. So . . .