a researcher unleashing an orange smoke flare in a glacier cave

See the eerie glacier caves carved by Mount St. Helens’s fiery breath

After the 1980 eruption, a glacier formed in the shadows inside the crater. Scientists—and our photographer—have explored its icy depths.

Scientist Andreas Pflitsch of Germany's Ruhr University, Bochum deploys a smoke flare in a glacier cave called Mothera in the crater of Mount St. Helens. The smoke will help reveal how such caves are sculpted by hot gases escaping from fumaroles—open vents in the volcano's crust. Pflitsch has also studied the hot winds that rush through subway systems.

Its creation began exactly 40 years ago, on May 18, 1980, the day Mount St. Helens exploded in the Cascade Range in Washington state. The eruption shaved 1,314 feet off the mountaintop. The force sent billions of tons of wet earth rushing down the North Fork Toutle River. A plume of ash shot 15 miles high, at 300 miles per hour. All that heat and pressure left behind a hole, a massive dark crater trapped in shadows at more than 6,200 feet—a brand new factory for snow and ice.

Shielded from sun much of the year, this horseshoe-shaped depression gave rise, as winter snows accumulated beyond the capacity of summers to melt them, to a young glacier. It’s now 660 feet

Unlock this story for free
Create an account to read the full story and get unlimited access to hundreds of Nat Geo articles.

Unlock this story for free

Want the full story? Sign up to keep reading and unlock hundreds of Nat Geo articles for free.
Already have an account?
SIGN IN

Read This Next

What bacteria lurk in your city? Consult the bees.
Is melatonin giving you nightmares?
Why are these orcas killing sharks and removing their livers?

Go Further

Subscriber Exclusive Content

Why are people so dang obsessed with Mars?

How viruses shape our world

The era of greyhound racing in the U.S. is coming to an end

See how people have imagined life on Mars through history

See how NASA’s new Mars rover will explore the red planet

Why are people so dang obsessed with Mars?

How viruses shape our world

The era of greyhound racing in the U.S. is coming to an end

See how people have imagined life on Mars through history

See how NASA’s new Mars rover will explore the red planet

Why are people so dang obsessed with Mars?

How viruses shape our world

The era of greyhound racing in the U.S. is coming to an end

See how people have imagined life on Mars through history

See how NASA’s new Mars rover will explore the red planet