Ancestral Puebloans Might Have Used Lava Cave Ice to Survive Droughts

Over 2000 years ago, the people that lived on the territory of what is now Western New Mexico have seen several droughts over the span of 800 years. Researchers have found evidence that it’s likely that these ancient people sought refuge from the heat inside volcanically-made caves and melted the ice found in those caverns carved by lava to sustain themselves during the droughts.

El Malpais National Monument in New Mexico
Ancestral Puebloans Might Have Used Lava Cave Ice to Survive Droughts

Researching the Lava-Made Caves

In 2017, Bogdan Onac, a paleoclimatologist from the University of South Florida in Tampa, led a research team to collect ice from the lava tubes in El Malpais National Monument in New Mexico. The goal was to gather ancient climate data but the team found much more than that. The frigid temperature of the caves remains at a constant 32° Fahrenheit, preserving the ancient ice and all that was trapped within it. Upon extracting a 1,9-foot long ice sample, the team saw 5 distinct charcoal circles along the length of the ice tube.

Lave Carved Tubes in El Malpais National Monument in New Mexico
Ancestral Puebloans Might Have Used Lava Cave Ice to Survive Droughts

Charcoal Particle Analysis

The presence of charcoal in the ice indicated fire. If there was fire deep within an icy cavern, it’s quite likely that there was human activity there. By radiocarbon-dating the charcoal found in the ice, researchers found that their age, ranging from A.D. 150 to A.D. 950, matches the timeframe of five drought events that happened in the area. This also indicates that the ancestral Puebloans kept track of these caves for hundreds of years in case their water supplies became necessary.

Researchers radiocarbon-dated charcoal layers preserved in an ice core in Cave 29;
Ancestral Puebloans Might Have Used Lava Cave Ice to Survive Droughts

Limited Time for Further Research

In addition to the charcoal rings in the ice, a charred piece of pottery was also found. This provides even more evidence that there was human activity in the caves. However, Onac claims that the pottery shard’s emergence from the ice is a bit concerning. Judging by photographic evidence from the 1980s, nearly a foot of ice has melted. The researchers need to move fast before more of the ice melts, potentially losing hundreds of years’ worth of data.