Summary:
- During the Paleozoic and Mesozoic, the seas rose over the continents.
- This is called a marine transgression.
- During a marine regression, the sea level retreats.
- These events leave characteristic rock layers known as sedimentary facies.
- Facies are characteristicrock layers, such as sandstone, shale, limestone for a marinetransgression.
- The reverse indicates a marine regress.
- The Paleozoics had four complete cycles of marine transgressions and regressions.
- The MesozoIC had two (Figure below).