If you find it is difficult to orient yourself within the geologic timescale, it may be easier to start with things you know. Aside from natural disaster, industry is most often the point at which human lives and geology intersect. Some familiar instances would be the rush for Cretaceous (144 MYA) gold, or perhaps fields of pumpjacks drawing up lakes of Pleistocene (1.6 MYA) oil. The earth is a fountain of industry. The bi-product of material extraction is that it cuts windows into ancient worlds.