G-d directs Noah and his family to take shelter within the Ark . Miraculously, representatives of every form of non-aquatic life gather together, enter, and all fit inside. They have provisions to live for an entire year. Astronomical cycles are halted during this period. Nature is modified by the Great Flood.
Giant species become extinct.
At the end of this ordeal, G-d makes a commitment to Noah that the world will never again be destroyed in this manner. A fear of natural disaster is now firmly implanted within Mankind. Noah becomes the founder of Mankind in the physical sense, as we are all his descendants. G-d foresees that Noah will have a descendent upon whom the world and the plan of creation can be firmly established. He will earn the role as a world founder in the spiritual sense.