The greater part of South America was above the sea during the Jurassic period, as it had been in the Trias. Marine deposits of the former period are found only along the western border of the continent, where they extend from 50 to 350 S. lat. Throughout the Jurassic the sea which covered this western coast retained its faunal connection with the central European region, and even the minuter divisions, the substages and zones of the European Jura, are applicable to the classification of the South American beds. The Boreal invasion, so conspicuous in California and Mexico, did not extend to South America, doubtless because of the warmer water on that coast.

In Europe the Jurassic rocks are magnificently displayed, but they differ much both in thickness and in character as they are traced from one country to another, which results from more frequent and more localized changes of level than had occurred during the Palaeozoic.