Fall 2006 - Raton Basin, Colorado

For the fall 2006 fieldtrip, there was renewed interest in exploring the K/T impact outcrops in honor of Jay, who had just returned from a sabbatical in Germany. We ventured out to the NM/CO border, where three prominent outcrops are located...

Day 1

We examine an outcrop with some nice spheroidal weathering features.

Salt River Canyon, Arizona

Day 2

Springerville Volcanic Field

La Ventana, a natural sandstone arch in Western New Mexico

El Malpais lava flow, New Mexico

As we drive closer to the NM/CO border, we stop at an outcrop containing shattercones, but these have nothing to do with the K/T event.

Day 3

We finally arrive at one of the three outcrops, and spend the entire day exploring. Here, Jay leads us to the first outcrop.

The double layer of the K/T boundary is clearly seen. The lower ejecta layer is a light gray claystone that's easiest to spot and contains ejecta from the impact. The upper layer is much darker and contains the extraterrestrial iridium spike from the impactor.

Variations in the thickness of the K/T boundary layer are still an area of active research.

Photos courtesy of Dave O'Brien