Every geologist should spend time in the Grand Canyon; nothing I've ever seen comes as close to giving you a physical sense of geologic time. Here is the Precambrian Vishnu Schist intruded by pink Zoroaster Granite.

Cardenas lava dike at Hance Rapid?

The Great Unconformity (Cambrian Tapeats sandstone I'm pretty sure, overlying Proterozoic schist)