What were rocks like four million years ago?

Four million years ago, during the late Miocene epoch, the Earth's geology was characterized by significant tectonic activity, leading to the formation of mountain ranges and changes in sediment deposition. Rocks from this period include sedimentary formations created from ancient river systems and coastal environments, as well as volcanic rocks from eruptive events. The climate was generally warmer than today, influencing erosion processes and the types of minerals present. Fossils found in these rocks often reflect the diverse ecosystems that existed at the time, including early ancestors of modern flora and fauna.