undifferentiated rock units
Choose a time period:
During an episode of mountain building, referred to as the Acadian Orogeny, igneous rocks were formed and older rocks were metamorphosed. These igneous and metamorphic rocks contain no fossils.
site tour | about the site | site map | site credits | page credits | help | FAQs | contact © | editorial policy | awards | teachers' guide | site generator | About RSS paleontology news: recent site additions: