03 October 2008
Vol 322, Issue 5898

About The Cover

Cover image expansion

COVER Ordovician sedimentary rocks at Presqu'île de Crozon, Brittany, France. These rocks show high-frequency cycles of less than 500,000 years between bay and open marine conditions. This and similar records allow reconstruction of global sea level from 550 to 250 million years ago. The pink boulder at the bottom is about 15 centimeters across. See page 64. Photo: Bilal U. Haq