Parallel to this, the melting of polar glaciers slowed down in the Middle Holocene to a point that allowed sea levels the world over to stabilize, at least to a greater degree than they ever had before. The combined effect of these two processes was dramatic; especially where great rivers met the open waters, depositing their seasonal loads of fertile silt faster than seawaters could push them back. This was the origin of those great fan-like deltas we see today at the head of the Mississippi, the Nile or the Euphrates, for instance.15
