Sand and gravel is deposited along the shoreline. Humans first appear in Utah during this epoch. Tertiary Pliocene 5 Volcanism continues in southwestern Utah. 24 Igneous intrusions continue to form in the Henry and Abajo Mountains. Igneous activity similar to that in the Oligocene continues until approximately 15 million years ago.
Basalt flows and volcanic cones form in southwestern Utah.
Regional uplift rejuvenates major river systems in the Rocky Mountains and the Colorado Plateau. The carving of the canyonlands begins. The igneous rocks that form the Henry, La Sal, and Abajo Mountains in southern Utah begin to intrude. Igneous activity produces intrusive rocks in northern Utah and volcanos in southwestern Utah. The majority of Utah's copper is probably associated with an Oligocene-age intrusion in the Bingham mining district, west of Salt Lake City.