Formerly, the Mississippi River carried sediments from eroding northern soils all the way to Louisiana, dropping them at its mouth, building land and forming a delta, then changing courses to build new deltas elsewhere.
(the Mississippi River; carried; sediments from eroding northern soils all the way to Louisiana, dropping them at its mouth, building land and forming a delta, then changing courses; from eroding northern soils all the way to Louisiana, dropping them at its mouth, building land and forming a delta; T:Formerly) (sediments; changing; courses; to build new deltas elsewhere; T:then)
the Mississippi River sediments
carried changing
sediments from eroding northern soils all the way to Louisiana, dropping them at its mouth, building land and forming a delta, then changing courses from eroding northern soils all the way to Louisiana, dropping them at its mouth, building land and forming a delta T:Formerly
courses to build new deltas elsewhere T:then