Rowan did not push deeper to investigate this barrier because he noticed it was filled with Ascendant Aura, most likely from the Divine Ascendant who had assimilated this continent to become his Natal Treasure.
However, this was not the reason he was investigating the depths of the earth. It was as he had once suspected; that calamity Gods could not be found under every continent, and the fact that his descent had been directly over the mouth of one of these elusive creatures while he was in the helpless form of a stone egg was not a coincidence.
The entire battle as it played out, including the death of the Calamity God, the summoning of Berrion the Undying, and finally a single Deific Explorer who stood above the battle and watched it all in grim amusement, as it mocked Rowan and all of existence.