Understanding Earth
JOHN GROTZINGER researches the chemical development of the early oceans and atmosphere and the environmental context of  early animal evolution at the Massachusetts Institute of Technology (MIT), USA.  THOMAS H. JORDAN is based at the  University of Southern California where his specialist topics include the nature of plate-tectonic flow and the question of mantle stratification.   FRANK PRESS has made pioneering contributions to the fields of Geophysics, Oceanography, lunar and planetary sciences and natural resource exploration. He has been named most influential scientist in the U--This text refers to an alternatePaperbackedition.