Bacteria move inland, still testing their breathy expertise in new niches. They quickly settle into rivers, ponds and the soils which erosion processes are rapidly creating.
A few ambitious microbes advance to a rough frontier. Expanses of desert become crust-covered communities. Although rare today, these ancient communities still bind the grains of desert sands.
Just as their early bacterial ancestors loved hot springs and acid, some microbes spread in icy climes. The particularly rugged outdoor types take to bare rock and mountain heights, with a breadth of metabolic strategies to meet their needs.