We end this rocky interlude with some information about the lichens which contribute to their weathering "Lichens are combination of two organisams: a fungus and an algae that work together -- relying on each other for life. Fungus gives the organism shape and draws moisture and nutrients from the rock to which it is attached. The algae lives within the fungus; it contains chlorophyll which allows the lichen to convert the suns energy into food." And as you can see the sun is setting. Time to go.