The Birth-Time of the World and Other Scientific Essays

Salt in the ocean, folded Alpine rocks and minute marks in minerals become evidence in John Joly's twelve scientific essays. Drawing on lectures and contributions to scientific reviews, he considers the Earth's age, erosion and mountain formation alongside the abundance of life, flower colours, photography and skating. The opening account explains how accumulated sodium can be used to estimate the ocean's history and the total work of erosion.

The geological essays connect radioactive heat with the shaping of mountain chains. In the discussion of Alpine structure, Joly weighs competing explanations for rock folds against temperature, pressure and the changing rigidity of buried material. Other pieces turn to the markings observed on Mars and the dark haloes found in mica. Readers interested in the history of scientific reasoning can follow an investigator moving between observation, calculation and speculation across very different scales of nature.