STORY AND PHOTOS BY KAREN BOSSICK

Josh Johnson turned his face up to the sky as snowflakes swirled down, tickling his nose.

“Just think—billions of these snowflakes once came down building up into a glacier,” he said. “And it’s their collective ability that has shaped many of the u-shaped valleys and elongated lakes around here.”

Johnson, the conservation project manager for Idaho Conservation League’s Ketchum office, had brought a small group of winter enthusiasts to a mountain slope near the top of Galena Summit where backcountry skiers and snowboarders carve powdery turns away from the lift lines.

It was the first of three guided snowshoe treks Johnson plans to lead this winter for those who want to learn about the natural environment during winter.

The second two-hour snowshoe hike will start at 9 a.m. Saturday, Jan. 20, at the Sawtooth National Recreation Area headquarters north of Ketchum. It will address how plants and animals adapt to survive Idaho’s typically harsh winters.

The third, at a time and place to be announced, will likely look at avalanche science.

On this particular outing, the group started out on a Forest Service road near the top of Galena Summit and soon turned their snowshoes uphill as they climbed towards a rock outcropping near what skiers call “The Cross.”

Johnson has been in the Wood River Valley for a short time, but he can’t help but be impressed with the evidence of glaciers he’s seen.

“The moraines I’ve seen in the Sawtooth Mountains are more definitive than any I’ve seen,” he said, referring to the piles of rocks and other debris a glacier collects and deposits as it moves along. “Ten to 15 minutes south of Stanley you can see a place where a glacier came right up to the road.”

Johnson, who got a graduate degree in geology at the University of Colorado in Boulder, worked for a couple summers in Grand Teton National Park.

There, he said, it was very easy to spot the work of glaciers, which carve out u-shaped valleys versus the v-shaped valleys that rivers carve out. And the same can be said for the terrain in Idaho’s central mountains.

Glaciers act like part-conveyer belts and part-bulldozers as they move rock and other debris along, eventually depositing them in ridges or moraines, he told the group.

“Moraines tell us how far a glacier went. And you can tell how old they are by dating the boulders that are left exposed to the atmosphere,” he said. “They date them by cosmogenic dating, measuring the accumulation of cosmic rays, which produce Beryllium-10.”

More recent glaciations within the past 15,000 years can be carbon dated, he added.

The Pinedale glaciation, named for Pinedale, Wyo., was the last of the major glaciations to appear in the Rocky Mountains. It lasted from approximately 30,000 to 10,000 years ago. Most of the glaciers in this area are from the Pinedale era, Johnson said.

“We’re talking about thousands of years instead of millions and billions of years so it’s easier to grasp,” said Johnson. “The last ice age was between 10,000 and 20,000 years ago.

In 1850 the Little Ice Age, a period of cooling that was technically not a true ice age, expanded small glaciers in the Wood River and Valley and Sawtooth. Since, glaciers have retreated due to warming temperatures and lack of precipitation. Today there are no glaciers in Idaho today.

Occasionally, snow fields—areas where snow deposits hang on through the summer into the next winter—can be seen on places like Mount Heyburn overlooking Redfish Lake, Johnson added.  But it has to be big enough to move to constitute a glacier.

Ice ages tend to be cyclical, occurring every 100,000 years or so, Johnson said. The next one is not due for awhile.

“And at this point, human activity would probably supersede it,” he added.

The falling snow had all but obliterated the view Johnson had hoped to offer his flock of how glaciers and avalanches, and snow and ice, had shaped the landscape by the time they reached the top. But occasional attempts by the sun to break through offered a faint glimpse of Big Wood River drainage below.

Glaciers came out of the Boulder-Mountain and the North Fork of Big Lost River area. They formed the Owl and Prairie Creek drainages in the Smokey, dead ending in the Big Wood River Valley.  Glaciers also came down both sides of what is now Trail Creek Road from Trail Creek Summit, extending as far as Wilson Creek a few miles north of Sun Valley.

“There is plenty of evidence of glaciers in the Pioneer Mountains, including the Wildhorse Canyon and the area around Kane Lake,” Johnson said. “There were lots of little glaciers but never a main glacier filling the valley like you see in the Upper Roaring Valley in Colorado. Glaciers never made it as far as Ketchum and Sun Valley, he said. Nor did a glacier ever flow down the Big Wood River valley.”

The moraines on the Sun Valley side of Galena Summit are not as visible as those in the Sawtooths but you can see some evidence, Johnson said. The Sawtooths evidence more glaciation because they got more precipitation than the Sun Valley side.

The group sidestepped across the hill, snowshoes sinking into six inches of very light powder even though there had been no fresh snow since a fast-moving storm dumped several inches of snow two weeks earlier.

As they did, Johnson spotted a snowshoe hare crouched under a whitebark pine. The hare eyeballed the group, presumably trying to decide whether to join in the discussion. Then it bolted for the sanctuary of another tree well.

“Wow! You don’t get to see that very often,” said Johnson.

A few minutes later, he hearkened to a sound of a red headed woodpecker banging on a tree. He quickly spotted it, noting the wood chippings it had left on the snow under the tree.

“I didn’t realize this was going to be a nature hike!” said Scott Friedman, a retired cardiologist now living in Sun Valley.

The fact that glaciers are receding is cause for alarm, said Johnson, particularly in areas like the Peruvian Andes and the Himalayan Mountains where people rely on glaciers for drinking water year-round.

“That’s a big deal,” said Betsy Mizell, ICL’s community engagement associate. “That’s why the ICL is always looking at what we can do to reduce our carbon footprint.”

The Boulder-White Cloud Mountains, which recently received wilderness designation, are one of the top three of 10 to 12 areas in the United States that are cited as refugees for wildlife like pika and wolverines and trees like whitebark pine and limber pine as climate warms, she added.

Knowing how glaciers carve the landscapes adds to our appreciation of what makes Idaho’s public lands so special, noted Johnson.

“The beautiful lakes, the high alpine lakes, have glaciers to thank for all that,” he said.

Friedman concurred: “I like learning how everything is formed. I’m amazed by the different rock formations in Idaho—and how they all tell a story. And so many different stories.”

IF YOU GO…

Josh Johnson’s Jan. 20 Winter Ecology Snowshoe Hike looking at plant and animal adaptation during winter will begin at 9 a.m. at SNRA headquarters several miles north of Ketchum on Highway 75. The hike is expected to cover about two miles with minimal elevation gain.

Though free, the hike is limited to 10 participants. To reserve your spot, email Johnson at jjohnson@idahoconservation.org. Or, call 208-726-7485.