How do the rocks of the Grand Canyon indicate marine transgressions or regressions?

Marine transgression and regression are the rising and falling of sea level over the continents. Sea level rises over the land - marine transgression, sea level retreats - marine regression.

The evidence for the marine transgressions and regressions can be found from the sedimentary rock record because these events leave characteristic rock layers - sedimentary facies. The Grand Canyon is an example that has an incomplete record of the four marine transgressions and regression of the Paleozoic