This is an image of flowing lava.
Click on image for full size
Earth was still very hot at this time, like a bubbling pot, and there was a lot of volcanic activity. Thus the surface of the Earth was covered with igneous rocks, there was no ocean, and no continents.
Igneous rocks are those which are formed by volcanoes, that is by the melting and remelting of the Earth's crust. In other words, these rocks are created from material of the Earth's interior, like the lava shown in this picture.
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