Even in the later periods the continuing lava flows and the incoming meteors kept the oxygen of the air almost completely used up. Even the early deposits of the soon appearing primitive ocean contain no colored stones or shales. And for a long time after this ocean appeared, there was virtually no free oxygen in the atmosphere; and it did not appear in significant quantities until it was later generated by the seaweeds and other forms of vegetable life.

The primitive planetary atmosphere of the volcanic age affords little protection against the collisional impacts of the meteoric swarms. Millions upon millions of meteors are able to penetrate such an air belt to smash against the planetary crust as solid bodies. But as time passes, fewer and fewer prove large enough to resist the ever-stronger friction shield of the oxygen-enriching atmosphere of the later eras.

1,000,000,000 years ago is the date of the actual beginning of Urantia history. The planet had attained approximately its present size. And about this time it was placed upon the physical registries of Nebadon and given its name, Urantia.

The atmosphere, together with incessant moisture precipitation, facilitated the cooling of the earth's crust. Volcanic action early equalized internal-heat pressure and crustal contraction; and as volcanoes rapidly decreased, earthquakes made their appearance as this epoch of crustal cooling and adjustment progressed.

The real geologic history of Urantia begins with the cooling of the earth's crust sufficiently to cause the formation of the first ocean. Water-vapor condensation on the cooling surface of the earth, once begun, continued until it was virtually complete. By the end of this period the ocean was world-wide, covering the entire planet to an average depth of over one mile. The tides were then in play much as they are now observed, but this primitive ocean was not salty; it was practically a fresh-water covering for the world. In those days, most of the chlorine was combined with various metals, but there was enough, in union with hydrogen, to render this water faintly acid.

At the opening of this faraway era, Urantia should be envisaged as a water-bound planet. Later on, deeper and hence denser lava flows came out upon the bottom of the present Pacific Ocean, and this part of the water-covered surface became considerably depressed. The first continental land mass emerged from the world ocean in compensatory adjustment of the equilibrium of the gradually thickening earth's crust.

950,000,000 years ago Urantia presents the picture of one great continent of land and one large body of water, the Pacific Ocean. Volcanoes are still widespread and earthquakes are both frequent and severe. Meteors continue to bombard the earth, but they are diminishing in both frequency and size. The atmosphere is clearing up, but the amount of carbon dioxide continues large. The earth's crust is gradually stabilizing.

It was at about this time that Urantia was assigned to the system of Satania for planetary administration and was placed on the life registry of Norlatiadek.