Newberry Crater National Monument

The native people living in the area we know as Central Oregon visited Newberry Crater for at least 10,000 years. They came for many of the same reasons people come today and also to quarry obsidian glass, an important material used to craft tools and projectile points. Throughout this time, Newberry Volcano was very active. Explosive eruptions of ash, pumice, and other volcanic products were often followed by the comparatively quiet flow of lava. New obsidian sources were created at about 6,700 years (Interlake and Gamehut flows), 3,500 years (East Lake flows), and 1,300 years (Big Obsidian flow). These eruptions and the eruption of Mount Mazama (which formed Crater Lake in the Cascade Range about 6,800 years ago) periodically buried existing landscapes, including traces of native encampments and quarry sites, under tons of volcanic ash and debris. These ancient buried camps are now archaeological sites, which could reveal volumes about the lives and culture of the humans who visited the crater for thousands of years.

Lava Cast Forest
by Judy Bever

About 6,000 years ago, eruptions along the Northwest Rift Zone leading from Newberry Volcano sent pahoehoe lava surging to the Earth's surface, spilling through the pine forest. Sap stored in live trees was converted to steam by super-heated lava. Steam then cooled the lava, in turn preventing some trees from being burned up completely. Trees were either turned to ash or transformed to charcoal depending upon availability of oxygen.

Molds formed when lava flowed around tree trunks, cooling quickly to fashion a hard coating. Where the flow of lava was rapid, molds did not form. When the lava slowly receded as a result of down flow drainage, the hardened molds of burned trees stood high above the lava surface. Later, charred wood rotted away, leaving lava molds. Roots of these vanished trees still remain 10 to 15 feet below the lava surface. Radiocarbon dates from these roots and recent work done in flow contact areas place the time of eruptive activity at about 6,000 years ago.

Locally known as Lava Cast forest, the region is named for the concentration of these distinctive volcanic features. Correct scientific terminology, however, designates the geologic wonders as "molds." The following definition explains this: A cast fills a mold, while a mold is formed around a object such as a tree.

From the back half of the trail near Trail Stop #9, one can look over the expanse of lava to an island in its midst. Like a river during a storm, the lava flow reached flood stage and then receded. Flood stages are recorded in "bathtub rings" left along the hillsides after lava drained away.

Not all lava trees are standing. When lava surged through the forest, some trees were pushed over by the force of the flow and were carried away, molds forming around some of these. Others remained, anchored by their roots. One of the largest horizontal molds may be seen at Trail Stop #10.

An aerial view of Newberry Volcano shows many fissures leading away from the mountain. Fissures are lines of weakness in the Earth's crust. Volcanic activity occurs along fissures because it is easier for magma to push its way toward the surface. Parts of the Lava Cast forest flow, Cascade Flow, and forest Road Flow are included in the Lava Cast Forest Geologic area. Recent work done on flow contacts has shown that all three flows are from the same short eruptive phase, refuting an earlier belief by geologists that each flow happened at a different time. Lava along the first half of the trail came from the fissure's north end.

Lava gradually cooled and hardened. Over time, wind-deposited ash accumulated in depressions in the rock. As seeds were introduced by wind, animals, or birds, reclamation of the lava flow area began. The struggle to survive harsh living conditions is exhibited by some stunted and misshapen plant forms.

Thousands of years have elapsed since Lava Cast Forest was created. Only recently, (geologically speaking), have the most primitive and simple plant life, mosses, and lichen appeared. They have initiated a chemical process, which if given enough time, will cause breakdown of the lava rock. In turn, the rock breakdown will assist in the formation of organic soil for the future forest. Rock breakdown and soil formation takes place over a span of many centuries in the dry, harsh climate east of the Cascades. Similar lava flows located in humid regions such as Hawaii, where rainfall is plentiful, experience immediate re-vegetation. Watch for mosses and lichen appearing as a grayish/greenish film on some rock surfaces.

Some of the trees seen out on the lava have died and lie where you see them today. Complete decay may take several hundred years to accomplish. As soils improve, shrubs, plants, and small trees ultimately become a climax of final community. If another eruption occurs, the cycle will begin anew.

Newberry Crater: Archeology and Geology

For many years, archaeologists and geologists have been fascinated by Newberry Crater for reasons far different than scenery or recreation. The Crater contains evidence of human activity that dates back thousands of years, and it also holds one of the most remarkable and accessible obsidian flows in the nation.

Archaeologists have uncovered several sites of ancient human activity in Newberry Crater. Using radiocarbon dating, workers have determined that a few of the numerous quarries, work sites, and campsites are close to 9,000 years old. The site on the west side of Paulina Lake is one of the most unique in the Northwest, because of its age, over 8,200 radiocarbon years old, and its ability to tell us how humans have adapted to the many volcanic eruptions that have occurred in the area. Among the artifacts that have been unearthed are spear or dart points that belonged to one of the earliest and least documented cultures in North America. Native Americans from all over the region used the obsidian found in the crater to make tools.

The Big Obsidian Flow within Newberry Crater is one of the geologic wonders of the Pacific Northwest, and, at 1,300 years old, it is the most recent volcanic eruption in Oregon. Created when rhyolite lava spilled to the basin floor from a high vent and formed frozen cataracts of black, volcanic glass, the Big Obsidian Flow has attracted human visitors for hundreds of years. Today, Forest visitors use the 0.9-mile interpretive trail on the flow to gain first-hand knowledge about the black glass and its history.

Visitors to the new monument will find evidence of a wider variety of volcanic events in a more compressed area here than anywhere else in the United States, and they are all easily accessible. Cinder cones, a variety of lava flows, Oregon's longest lava tube cavern, and fields of pumice are some of the volcanic features that make this place remarkable.


What is it? Obsidian. is a natural volcanic glass—remarkably, similar to the glass in your windows. It is not made of crystals, like other rocks are, but has the disordered internal structure of a liquid.

How does it form? When a lava is especially rich in silica (SiO2), it has the stiff consistency of taffy or cookie dough. This is because the silicon (Si) and oxygen (O) atoms stick together, forming a three-dimensional "web" that hinders movement inside the liquid. Because the lava cools fairly quickly above ground, it hardens to rock before its atoms have time to move about and organize themselves into the symmetrical, closely-packed structures of crystals.

What is it used for? Native American Indians have fashioned knives. Arrowheads, and other sharp tools from obsidian for the past 10,000 years or more. High-quality obsidian from Newberry Crater was traded throughout the Northwest. Because obsidian biases are sharper than steel, they cause little scarring; some doctors use them today for delicate operations, such as eye surgery.

Why can't I take a piece home? Newberry National Volcanic Monument was established by the U.S. Congress on Nov. 5, 1990, in order to "preserve and protect for present and future generations Newberry's remarkable geologic land forms. Each of us plays a vital role in caring for our National Monument. Damaging or removing even a small sample of rock degrades our resource and it's illegal.

Contact Information:
(541) 593-2421

Published: 29 Apr 2002 | Last Updated: 13 Sep 2011
Details mentioned in this article were accurate at the time of publication

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