Imagine standing at the bottom of a long mountain valley, here, just over seven million years ago. A lush blanket of grass covers the length of the valley, swaying wave-like in a dry, light breeze and few trees are visible. The sound of munching grass comes from a wary herd of horses.
Suddenly, in the distance, a thundering explosion shakes the grounds. Birds fly from the grasses into the sky. What happened?
Less than an hour later the valley to the east quickly fills with a vibrant tidal wave of fiery volcanic Ash, gasses, and debris. This onrushing cloud of death flows down the valley toward you at high speed, engulfing and incinerating all life.
It’s good you were not there. Ash fall from the volcanic eruption over 80 miles away covered the region. A burning deposit, an ignimbrite, settled into the ancient valley bottom, welded, and cooled into a thick layer.
This dry landscape once dominated by grasses was home to grazers such as camels, elephants, and rhinos.