[X-ray technology has allowed researchers a glimpse at the reaches
of the Yellowstone landmark’s prized stone and its importance to
Indigenous people.]
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SUNDAY SCIENCE: OBSIDIAN CLIFF – HUMANITY’S TOOL SHED FOR THE
LAST 11,500 YEARS  
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Jim Robbins
March 20, 2023
New York Times
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_ X-ray technology has allowed researchers a glimpse at the reaches
of the Yellowstone landmark’s prized stone and its importance to
Indigenous people. _

Obsidian Cliff, made of volcanic glass used for milleniums as an
extremely sharp tool for hunters’ weapons., Art World/Alamy

 

YELLOWSTONE NATIONAL PARK, Wyo. — Near the north entrance, an
imposing mountain of black glass rises against the blue sky.

Spanning more than five square miles, the dark, sometimes translucent
mass was formed from a rhyolitic lava flow that oozed out of the magma
chamber of Yellowstone Caldera beneath the park, and cooled rapidly in
the bitter cold of a glacial maximum, about 180,000 years ago.

Known as Obsidian Cliff
[[link removed]], the
Yellowstone mountain is one of the country’s highest quality
deposits of “the sharpest natural substance on Earth,” according
to Douglas H. MacDonald, a professor of anthropology at the University
of Montana and the author of “Before Yellowstone: Native American
Archaeology in the National Park.”

Obsidian is among the most prized tool stones in the world, and this
particular deposit, nearly 100 feet thick, is exceptional because of
its continual use by Indigenous people since the last ice age. Over
the last 11,500 years or so, the stone has been fashioned into deadly
knives, razor-sharp spear points, darts for atlatls, or
spear-throwers, and arrowheads.

The cliff is “nationally significant because we had Native American
groups from all over the country visiting it and collecting the stone
and trading for it,” Dr. MacDonald said.

For modern day researchers, the obsidian columns of Yellowstone have
helped to reveal the travels and migration of people thousands of
years ago. X-ray fluorescence technology has been used to identify the
unique geochemical fingerprint of each separate deposit of obsidian,
pinpointing the provenance of artifacts found elsewhere. Obsidian from
here has been found across the continent.

A fingerprint for the most prized tool stone in paleoindian cultures
transformed the field. It provides a window into the past, a flow
through both space and time over thousands and, in some places,
millions of years. It opens up unknown and unimagined connections and
deepens the understanding of migration, networking and trade in
populations around the world.

“We can figure out where people are moving on the landscape and from
there how the tools themselves reflect their strategies and
culture,” said Elizabeth A. Horton, the archaeologist for
Yellowstone, as she displayed obsidian knives and spear points from
the park’s archives. “How did they interact with this landscape?
Where did people go to visit? What was at that location?”

The application of X-ray technology to archaeology arose in the 1960s
“and changed everything,” said M. Steven Shackley, director of the
Geoarchaeological XRF laboratory in Albuquerque and author of “X-ray
Fluorescence Spectrometry (XRF) in Geoarchaeology.” “Before that
you had to infer. They either just guessed or didn’t do it.”

In recent decades, the technology has become easier to use, more
portable and far less expensive.

The smooth, sensuous black glass has been an important part of
hunter-gatherer cultures for about two million years, going back to
Homo habilis, one of the first human ancestors who made crude stone
tools. (A very modern reference would include the fictional land of
Westeros, the setting for the HBO series “Game of Thrones,” where
it was called dragon glass and made by “the fires of the earth.”)

Researchers are using the approach to study both newly discovered
artifacts and to re-examine existing collections. Archaeologists at
Yale recently deployed the X-ray fluorescence technology on obsidian
artifacts that were gathered at the university’s Peabody Museum in
the 1960s from two key sites in southwestern Iran.

The tools, which date back nearly 10,000 years, were originally
believed to have come from two sources on the Deh Luran Plain in Iran.
But the analysis showed that the volcanic glass came from seven
places, including Nemrut Dağ, a dormant volcano that was more than
1,000 miles from the excavation sites in what is now southeastern
Turkey and in Armenia. Those findings led to the realization that
Neolithic social networks were much larger and settlements were more
complex than originally thought.

Elizabeth Horton, a Yellowstone archaeologist. Natalie Behring for The
New York Times

“Tracing these obsidian artifacts from their sources to their end
points offers insight into how they moved from hand to hand to hand
over time,” Ellery Frahm, an archaeological scientist at Yale and
the lead author on the paper
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X-ray fluorescence can be done in the field with an instrument the
size of a hand drill, reducing a process that used to take days or
weeks to seconds.

The technique is being used widely across the American West, and
Yellowstone has a number of projects underway.

The geochemical fingerprint of the cliff’s volcanic glass has been
found all around the West, as well as in Canada. Area tribes “all
knew about it, all the archaeological sites in Montana that are
important have some form or another of obsidian, and most of it comes
from this place — Obsidian Cliff,” Dr. MacDonald said. “All of
the tribes in Montana, Wyoming and Idaho were going out of their way
to get it.”

One lingering mystery of Obsidian Cliff stumps scientists to this day:
How, some 2,000 years ago, did hundreds of pounds of obsidian wind up
at what is now Hopewell Culture National Historical Park in Ohio,
about 1,700 miles east of Yellowstone. Researchers do not know if the
material traveled through trading networks or was gathered by people
who went on a special journey to the cliff. That’s one of the major
shortcomings of the X-ray analysis.

“If someone sends me an artifact, I can determine the origin of it
with a good degree of confidence,” Dr. Shackley said. “But
determining how it got there is the kicker.”

In the early 1890s, excavators digging in Mound 25 at the Hopewell
location near Chillicothe, Ohio, found an altar with more than 100
burned and broken obsidian spear points, also known as bifaces. One
point was more than 17 inches long and 6 inches wide and believed to
have been designed for ceremonial purposes. About three-fourths the
obsidian at Hopewell has been traced back to Obsidian Cliff using the
X-ray tech.

“The largest of these bifaces are master works, really
remarkable,” said Timothy D. Everhart, a museum curator and
archaeologist at the Hopewell park.

The allure of Obsidian Cliff’s stone glass can be seen as well as
felt in its efficient use as a sharp weapon. In a recent
paper, researchers outlined its noteworthy elements — abundance,
access, aesthetics and quality
[[link removed]].

There is so much that the obsidian here could fill 3,000 stadiums the
size of the Rose Bowl in California, Dr. MacDonald said.

The stone at Obsidian Cliff has few inclusions, which means it lacks
the presence of mineral crystals that can weaken the stone’s
structure, and that contributes to the high quality of the Yellowstone
obsidian and the easy transformation into sharper blades, Dr.
MacDonald said.

“It comes in a variety of colors and is much more translucent than
other sources,” he added. “That increased its value.” In
addition to black, colors reported atop the cliff include brown, red,
mahogany, gray and green.

This arrowhead from Obsidian Cliff glass is about 1,500 years old.
Natalie Behring for The New York Times

In Idaho, west of Yellowstone, Bear Gulch has a comparable
high-quality obsidian, although it is jet black and less translucent.
There are at least eight known obsidian quarry sites in Yellowstone
and many others in the region.

All obsidian shares certain critical features that made it
indispensable. It fractures conchoidally — into smooth, curved
pieces. It was easy to knap, or to flake off, pieces into utilitarian
shapes and didn’t need to be tempered or treated with heat as some
tool stones do. “You can pick it up off the ground and go right to
work,” said David Wescott, an editor of The Bulletin of Primitive
Technology and a longtime knapper.

Sharpness, though, is the main draw.

“If you look at a surgical scalpel and a fresh obsidian flake under
a microscope, the obsidian edge makes the surgical scalpel look like a
dull ax,” Dr. Frahm said. “It is razor sharp. It cuts very, very
cleanly.” In fact, some surgeons use obsidian scalpels.

It is so sharp that many people who work with it, including the staff
members of the Yellowstone archaeology lab, keep a box of Band-Aids
within reach.

The massive wildfires of 1988 in Yellowstone burned off trees and
other vegetation and allowed archaeologists a virtually unobstructed
view of the ground on top of the cliff. One archaeological survey
found 59 different places where obsidian was quarried in some fashion.

In another survey in 2014 Dr. MacDonald and his team found millions of
artifacts on the cliff, including arrow and spear points, along with
billions of pieces of debitage, the stone flakes that remain after
crafting points. Numerous obsidian boulders were smashed and broken
open.

As the climate grows warmer in Yellowstone, many of the snow fields
are receding and previously unknown artifacts are being revealed,
sometimes on wood shafts that were preserved by the snow cover.

Some obsidian artifacts. Natalie Behring for The New York Times

Obsidian Cliff is closed to pedestrians, but it is along one of the
park’s main roads and people can park at an interpretive kiosk.
Collecting is forbidden, but it is permitted at other sites on federal
land in other parts of the country.

Like Mr. Wescott, people still harvest the glassy stone to create
obsidian tools or to hunt with atlatls and arrows with obsidian
points. Knapping a 6-inch long, 2-inch wide spear point, Mr. Wescott
said, “takes the better part of a day.”

But 21st-century uses build on the long history of obsidian toolmaking
that keeps reaching farther back into time. A group of European
archaeologists recently published a paper on their discovery of a
“stone tool workshop”
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obsidian ax heads at a single site in the Awash valley of Ethiopia,
dated to 1.2 million years ago.

Obsidian objects have long been imbued with profound spiritual and
mystical properties of other millenniums. The name of the Aztec god
Tezcatlipoca was Lord of the Smoking Mirror, a reference to obsidian.
An Aztec mirror displayed at the British Museum was used in the 16th
century by John Dee, an adviser to Queen Elizabeth I, as a tool for
divination. X-ray fluorescence tracked the source of the “spirit
mirror” obsidian to Mexico to reveal its Aztec origins.

In ancient Mexico, powdered obsidian was mixed with quartz and
sprinkled in someone’s eyes to treat cataracts.

The Crow people of southern Montana, who gathered much of their stone
for tools from Obsidian Cliff, still wear red obsidian arrowheads
“for spiritual protection,” said Timothy McCleary, the former
archaeologist for the Crow tribe, who now teaches at Little Big Horn
College on the Crow reservation. The arrowheads are passed down
through families, he said.

“Someone might find themselves in a dangerous situation, and it
protects them from any danger,” he said. “Where I’ve seen it
most commonly is on firefighters when they go to fight forest
fires.”

Obsidian Cliff, which is designated a National Historic Landmark,
still figures in the lives of many tribes. “Anytime we go to
Yellowstone, that’s a really powerful place,” said Louise E.
Dixey, cultural resources director for the Shoshone-Bannock tribes in
Idaho. “Prayers are always said there. We go back every year to
remind our people where we came from and remind the non-Indian public
that these are our original homelands.”

_JIM ROBBINS has been writing about science and environmental issues
since 1978. He is a regular contributor to The New York Times, Yale
University’s e360, and Condé Nast Traveler. He has also written
for Audubon, Travel Holiday, Smithsonian, Scientific
American, Vanity Fair, The London Sunday Times, The Boston
Globe, Conservation, Sierra, and High Country News, and has
appeared on NPR, ABC’s Nightline, The McNeil Lehrer Report, and the
BBC. He has covered environmental and science stories across the
United States and around the globe. He lives in Helena, Montana._

_His books include Last Refuge: Environmental Showdown in the
American West, A Symphony in the Brain: The Evolution of New
Brainwave Biofeedback, The Man Who Planted Trees, and The Wonder of
Birds, as well as two books on the brain co-authored with Dr. Les
Fehmi. _

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