The recent story of a black rock

In June 1867 – a few months before Alaska became part of the United States through the transfer of $7.2 million to Russia – William Healey Dall picked up a shiny black stone from the river bank.

Dall was located near the mouth of the Nowitna River, which flows into the Yukon River between the present-day villages of Tanana and Ruby.

He stowed the interesting stone, scribbled a note about it in his journal, and continued his expedition. His mission was to explore a possible route for a telegraph line along the Yukon River that could connect the United States to Europe via the Bering Strait.

157 years later, Jeff Rasic held the same piece of obsidian during a visit to Washington, DC.

Rasic, an archaeologist and science coordinator for all 15 National Park Service units in Alaska, was traveling to meet with colleagues in West Virginia. He had added a day to his trip from his home in Fairbanks to visit the Smithsonian Institution in Washington.

There, he went straight to the facility's geological collection to further research one of his favorite projects: the sources of ancient obsidian tools found in Alaska.

Obsidian is a black, often translucent stone. During volcanic eruptions, magma sometimes seeps out and turns into this natural glass when it cools.

Obsidian is hard, durable, and can be worked to a razor sharp edge. Archaeologists find it in places across Alaska where people once sharpened spears, scraped hides, and made knives. Hunters in the far north once planted obsidian in the seats of their boats to attract whales.

“It is a chance discovery by nature,” said Rasic. “Because it is so rare, we can very precisely attribute the artifact to its source.”

Much of the obsidian used by humans in Alaska comes from a source called Batza Tena near the Indian River in interior Alaska. There are several other notable obsidian deposits, including near Wiki Peak in the Wrangell Mountains, the Okmok Caldera in the Aleutian Islands, and springs in southeast Alaska.

Rasic is always on the lookout for samples of Alaska obsidian, hoping to uncover long-forgotten sources and discover what the stones can tell us about interactions between Alaska Native peoples.

For example, he once linked an obsidian artifact from a 3,000-year-old site on the Aleutian island of Unalaska to a spring in the Wrangell Mountains, just 20 kilometers from the Canadian border.

“It was a big surprise to find something from interior Alaska (in the Aleutian Islands),” Rasic said.

How does Rasic tell the difference between Wiki Peak obsidian and obsidian from Okmok volcano? He carries a handheld device that looks like a barcode reader.

At the Smithsonian National Museum of Natural History in Washington, Rasic pointed his device at the black stone that Dall had reported as a possible geological source. He pressed the shutter button. The device emitted a controlled beam of X-rays that excited electrons in the stone. Rasic was able to immediately determine the elemental concentration in this piece of obsidian.

Dall's rock was a perfect match for Batza Tena, which makes sense since the source is 70 miles from the beach where Dall collected it.

Rasic was pleasantly surprised to find that this piece of obsidian had been worked by ancient people. He thought the stone might have come from one of those unknown rock outcrops he is always looking for.

Dall's obsidian “obviously came from a nearby camp and was brought there by people with connections to the Koyukuk River and the Batza-Tena spring,” Rasic said. “I was happy to have solved a piece of the puzzle and also to have the chance to overlap in some way with this famous explorer.”

This naturalist and Alaska lover has left his name on more Alaskan creatures and features than anyone else, including the Dall sheep and the white-handed porpoise.

His name is also found on Dall Glacier, Dall Point, Dall Island, Dall Lake, Dall Mountain, Dall Ridge, Dall River, and Mount Dall.