Pliocene Epoch, the geologic epoch that began about 6,000,000 years ago and lasted about 4,000,000 years. It is a subdivision of the Tertiary Period of the Cenozoic Era. Great uplifting occurred in the mountains of the northwestern United States during the Pliocene Epoch. Pliocene formations in California are sources of petroleum.
La Brea Tar Pits, an area in Hancock Park, Los Angeles, where there is a natural accumulation of sticky asphalt derived from an ancient petroleum seep.
Diamonds are beautiful and popular - but not everyone can afford these gems. While man-made versions are less expensive, most lack the luster and brilliance of the real thing, except moissanite. See how it compares!