Curious Alaska: Why are there sand dunes in Anchorage’s Kincaid Park?

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Question: How and when did the sand dunes form at Kincaid Park? Are they natural or man-made? Why aren’t they elsewhere along the coast?

Curious Alaska: The Kincaid Park sand dunes were formed due to a strong wind that lifts sand from below and deposits it up above, said Dick Reger, who has worked in Alaska geology for over half a century. He retired from the state geological survey in the 1990s and has since been working as a consultant.

“I’ve been studying Alaska geology since 1957,” he said during a recent phone call. So, he’s familiar with the sand dunes in Kincaid and how they got there.

The dunes in Kincaid are actually the same as the dunes along the east side of Fire Island, across the water. And they both ended up there in the same way: ferocious winds.

“The Turnagain Arm winds are famous for their frequency and their velocities,” Reger said.

When those winds sweep along the exposed, sandy bluffs that border the park, they pick up the sand and blow it upward. The reason the dunes are only in specific spots is likely because the bluff below does not have any vegetation to protect the sands from the wind and keep them in place, instead leaving the sand vulnerable to strong drafts.

There, the winds shift, twisting in a circular vortex and dumping the sand along the dunes. It’s a little like a sandy tornado.

The vortex, parallel to the bluff, dumps sand, vegetation grows, more sand gets dumped, and eventually it becomes a sand dune, Reger said.

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The dunes are a dramatic and sloping feature adjacent to a motocross track and a short walk from the parking lot. On a recent Tuesday afternoon, school-aged children ran through the trees while others with picnic supplies, dogs and books looked out toward the water.

Tegan Thomas, 24, and Emily Lessard, 25, had taken their hammocks out to the dunes to relax under the cloudless sky before work that afternoon. Thomas grew up nearby and used to play in the sand. She said she’d always wondered how the dunes got there.

Now, the dunes serve as a nice place to hang out and enjoy the sun.

Plus, Lessard said, you can feel the sand between your toes.

“It feels kind of like the beach,” Thomas said.

And the sand itself has its own origin story that dates extremely far back in time.

It starts sometime around 30,000 years ago, during the last Ice Age. The Anchorage area was inundated by glaciers.

As those glaciers moved, they scoured over rock, grinding it up into a finer material left behind as deposits, Reger said. That material is what now gets picked up and swept into the dunes.

The Kincaid dunes have shown up in multiple Daily News stories — from serving as the site of an avalanche that buried three young Nordic skiers last year to their inclusion in an article about nearby beached beluga whales in 2014.

But they’re not the only sand dunes in the state, Reger said.

“They’re very common in the Interior, especially south of Fairbanks and even down the Alaska Highway,” he said.

There are also the famed Great Kobuk Sand Dunes in Northwest Alaska, as well as a 100-foot-thick sand sheet west of Nenana where sand has been blown for tens of millennia.

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