Trinidad Lake State Park
The K-T Boundary

In hiking around in the Long's Canyon Watchable Wildlife Area keep your eye out for the K-T Boundary, a thin white line in the rock just below some of the sandstone bluffs. "K-T Boundary" signifies an event of global proportions that marked the end of the Cretaceous Period and the beginning on the Tertiary Period in geologic history. That thin white line also marks the demise of the dinosaurs some 65 million years ago.

One of the minerals in that white formation is iridium, deposited in a single layer around the entire planet when a massive meteor (some say asteroid) slammed into the planet and vaporized near the Yucatan peninsula in Mexico. In that impact, molten and pulverized rock was ejected high into the atmosphere and even back into space. The impact formed a 125-mile wide crater near what is now Chicxulub, Mexico. The shock wave from the impact spread across the surface of the planet with tsunamis and fireballs spreading radially in all directions, with nearly the entire surface of the planet being affected. With all the smoke from the fires, the sun's light and heat at the surface of the planet were affected and the planet cooled off. Atmospheric water, combined with all the smoke and ash in the air, condensed and fell back to Earth as acid rain. Some theories suggest that event (and its aftermath) caused such an environmental catastrophe that all the dinosaurs and about 75% of all life on Earth were wiped out over the next few years.

The K-T Boundary layer itself is composed of what is called "claystone," a mix of iridum, shocked quartz and melted clay. Iridium is rare on Earth but common in meteorites (and asteroids). Shocked quartz is unique to impact craters. The mix with melted clay resulted from the heat generated in the horrendous fires that burned all across the planet. And the crumbly black rock just above that line of shocked quartz and iridium is the charcoal remains of the prehistoric forest that burned here in the aftermath of that impact event.