Climatic Change

, Volume 1, Issue 4, pp 355–382

Effects of a variable sun at the beginning of the Cenozoic era

  • Peter Sonnenfeld

DOI: 10.1007/BF00135156

Cite this article as:
Sonnenfeld, P. Climatic Change (1978) 1: 355. doi:10.1007/BF00135156


Periodic bursts of increased ultraviolet radiation, possibly caused by a long-term breakdown of the ozone layer in late Cretaceous to early Tertiary time, can explain the staggered extinctions of terrestrial, marine and flying reptiles, of invertebrate plankton feeders. Inherited protective devices and habits of surviving genera support this hypothesis. Increased radiation also explains the concurrent decrease in aridity indicated by the world-wide absence of marine salt and potash deposits from Maestrichtian, Danian, Paleocene and Eocene sediments, the poleward displacement of marine tropical faunas and the warm-temperate forests in high latitudes. A magnetic reversal is too brief an event to be responsible for the faunal changes; variations in solar radiation of the order of the Kelvin-Helmholtz time, or 30–40 million years, with superimposed shorter periodicities are a probable cause.

Copyright information

© D. Reidel Publishing Company 1978

Authors and Affiliations

  • Peter Sonnenfeld
    • 1
  1. 1.University of WindsorWindsorCanada

Personalised recommendations