A fragment of the Sumerian Creation Epic?

from the preamble to ‘Enkidu and the Netherworld’ (Gilgamesh tablet 12):

...In most ancient times ...

When Heaven was severed from Earth

When Earth had been parted from Heaven,

When the name of Man had been fixed,

When the god An had carried off Heaven for himself,

And the god Enlil had taken the Earth for himself,

And the goddess Ereshkigal had been given the Netherworld (Kur?) as        gift/dowry? [or Kur had carried her off?]

When He had set out, when He had set out,

          When the father had embarked for the Netherworld

          When Enki had set out for the Netherworld,

Small ones rained down on the Lord,

(and) Large ones rained down on the god Enki:

          The small ones were pounding stones

          The large ones were millstones (?)

They poured down on the deck of the god Enki’s boat

          like bobbing turtles.

Against the Lord, the water swallowed the prow of his boat like a wolf,

Against the god Enki, the water sprang at the stern like a lion

[This passage, evidently describing a great flood, is repeated like a refrain in the story that follows: afterward Inanna choose a drift-wood tree which she planted in her shrine and later had furnishings fashioned from it]