DESCRIPTION:
Newberry Volcano and Caldera, Oregon

Newberry85_newberry_caldera_obsidian_flow_08-20-85.jpg
Newberry Caldera, with the Big Obsidian Flow. Paulina Lake is on the left and East Lake is on the right.
USGS Photo taken August 20, 1985, by Lyn Topinka.
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Newberry Caldera

Location: Oregon

Latitude: 43.722 N

Longitude: 121.229 W

Height: 2,434 Meters (7,985 Feet - Paulina Peak)

Type: Shield Volcano, Caldera

Number of eruptions in the past 200 years: 0

Latest Eruptions: About 1,300 years ago ²

Present thermal activity: Hot springs in eastern crater lake.

Remarks: The most recent eruption 1,300 years ago produced the Big Obsidian Flow. ²

Newberry volcano lies 65 kilometers east of the crest of the Cascade Range and is one of the largest Quaternary volcanoes in the United States -- its broad shield-like shape covers more than 1,300 square kilometers. A summit caldera 6-8 kilometers across contains numerous rhyolite lava flows and domes and related pyroclastic debris; lava flows and tuffs of basalt and basaltic andesite are less common. The flanks of the volcano are composed of rhyolitic to andesitic pyroclastic-flow deposits, dacitic and rhyolitic lava flows and domes, and hundreds of scoria cones and lava flows of basalt and basaltic andesite. An active hydrothermal system is evidenced by warm springs in the caldera and by drilling that has penetrated zones with temperatures in excess of 265 degrees C. at depths of 932 meters.

Newberry volcano is a broad shield volcano located in central Oregon. It has been built by thousands of eruptions, beginning about 600,000 years ago. At least 25 vents on the flanks and summit have been active during several eruptive episodes of the past 10,000 years. The most recent eruption 1,300 years ago produced the Big Obsidian Flow. Thus, the volcano's long history and recent activity indicate that Newberry will erupt in the future.

[Graphic,77K,InlineGIF]
Index map showing Newberry volcano and vicinity

The most-visited part of the volcano is Newberry Crater, a volcanic depression or caldera at the summit of the volcano. Seven campgrounds, two resorts, six summer homes, and two major lakes (East and Paulina Lakes) are nestled in the caldera. The caldera has been the focus of Newberry's volcanic activity for at least the past 10,000 years. Other eruptions during this time have occurred along a rift zone on the volcano's northwest flank and, to a lesser extent, the south flank.

Many striking volcanic features lie in Newberry National Volcanic Monument, which is managed by the U.S. Forest Service. The monument includes the caldera and extends along the northwest rift zone to the Deschutes River. About 30 percent of the area within the monument is covered by volcanic products erupted during the past 10,000 years from Newberry volcano.

Before the Ice Age, Mount Newberry formed as a shield volcano, the highest point of the Paulina Mountains, set apart from the Cascade Range to the west. This peak may have reached a height of ten thousand feet before it collapsed to form a crater. Today, the highest point of the crater is 7,897 foot Paulina Peak.

Native Americans were living in Central Oregon when the last volcanic action occurred about 600 A.D. The first recorded visit by whites to the Newberry Crater area was in 1826, when Peter Skene Ogden, a Hudson's Bay trapper, led his party west.

Newberry Crater is named for Dr. John Strong Newberry, a physician and naturalist, who accompanied the 1855 Topographic Corps Expedition, mapping future railroad routes. Paulina Peak is named for a Snake Indian chief who led raiding parties against white settlers in the 1850s and 1860s.

The Big Obsidian Flow, created 1,300 years ago, covers 700 acres. The black, shiny obsidian field is easily accessible from good roads or a new trail that traverses the flow.

Newberry Crater is named for Dr. John Strong Newberry, a physician and naturalist, who accompanied the 1855 Topographic Corps Expedition, mapping future railroad routes. ... John Strong Newberry (1822-1892) grew up in Ohio, but came to know much of the geology and botany of the West. In 1903 Dr. I.C. Russell examined central Oregon for the U.S. Geological Survey and attempted to use the name Mount Newberry for the Paulina Mountains and Paulina Peak. Dr. John Strong Newberry was a geologist with the Pacific Railroad Surveys in 1855 when they surveyed the central Oregon area. The name Mount Newberry never found acceptance but the caldera at the summit has become known as Newberry Crater.

Paulina Peak is named for a Snake Indian chief who led raiding parties against white settlers in the 1850s and 1860s. ... Paulina Peak, Paulina Creek, Paulina Lake, and North Paulina Peak are a few of the many features in Central Oregon named for Chief Paulina. Chief Paulina was blamed for the deaths of many miners, trappers, and settlers during 1866 and 1867. After raiding several ranches in the John Day country he was pursued by a group of ranchers and shot by Howard Maupin (town of Maupin is named for him).

Newberry Volcano, centered about 20 miles southeast of Bend, Oregon, is among the largest Quaternary volcanoes in the conterminous United States. It covers an area in excess of 500 square miles, and lavas from it extend northward many tens of miles beyond the volcano. The highest point on the volcano, Paulina Peak with an elevation of 7,984 feet, is about 4,000 feet higher than the terrain surrounding the volcano. The gently sloping flanks, embellished by more than 400 cinder cones, consist of basalt and basaltic andesite flows, andesitic to rhyolitic ash-flow and air-fall tuffs and other types of pyroclastic deposits, dacite to rhyolite domes and flows, and alluvial sediments produced during periods of erosion of the volcano. At Newberry's summit is a 4- to 5-mile-wide caldera that contains scenic Paulina and East Lakes. The caldera has been the site of numerous Holocene eruptions, mostly of rhyolitic composition, that occurred as recently as 1,400 years ago. ...

Newberry lies 40 miles east of the crest of the Cascade Range in a setting similar to Medicine Lake Volcano in California (Donnelly and others, this publication). Both volcanoes have the same shape, are marked by summit calderas, contain abundant rhyolitic domes and flows, have widespread ash flows in addition to the more areally extensive basalt and basaltic-andesite flows and their related cinder cones, have similar petrochemistry, and have been the sites of eruptions of pumiceous tephra and obsidian flows during the last few thousand years.

Newberry lies at the west end of the High Lava Plains, a terrain formed of Miocene to Quaternary basalt flows and vents punctuated by rhyolitic domes and vent complexes (Walker and others, 1967; Green and others, 1972; Walker and Nolf, this vol.). The rhyolitic rocks show a well-defined montonic age progression starting at about 10 million years east of Harney basin and decreasing to less than 1 million years at Newberry's eastern border (Walker, 1974; MacLeod and others, 1975; McKee and others, 1976). Newberry rhyolites appear to be a continuation of these age-progressive rhyolitic rocks.

Complex Faulted Terrain

A complexly faulted terrain surrounds Newberry. The northeast-trending Walker Rim fault zone impinges on Newberry's southern flank but offsets only its older flows. A zone of faults that offsets older flows on the lower northern flank extends northwestward into the Cascade Range at Green Ridge. Although Newberry lavas obscure the relations of the Walker Rim and Green Ridge fault zones, they likely join beneath Newberry and represent but one curving fault system. The Brothers fault zone, a major west-northwest-trending zone of faults, extends across the extreme northeastern flank but does no apparently offset surficial Newberry flows. It probably extends at depth to join or abut against the Green Ridge-Walker Rim fault zones.

Lava Flows and Lava Tubes

The north and south flanks of Newberry Volcano, which extend the greatest distances from the summit caldera, are almost exclusively veneered by basalt and basaltic andesite flows and associated vents. The basalt flows form much of the surface in a broad region extending far north of the volcano (Peterson and Groh, 1976) as well as southward to the Fort Rock basin. Individual flows are a few feet to more than 100 feet thick and cover areas of less than one square mile to many tens of square miles. Flow margins are commonly well preserved even on older flows, but the flows are complexly interwoven and it is difficult and time consuming to trace individual flow boundaries. Most flows are of block or aa type; pahoehoe surfaces occur locally on a few lower flank flows. Lava tubes are common, and some extend uncollapsed for distances of one mile (Greeley, 1971); some lower flank flows may have been fed by tube systems. Casts of trees occur in many flows, particularly the younger ones.

The basalt and basaltic andesite flows can be readily divided into two groups on the basis of their age relative to Mazama ash (carbon-14 age 6,600-6,700 years) derived from the volcano at Crater Lake 70 miles distant. The youngest lava flows overlie Mazama ash, and their carbon-14 ages range from 5,800 to 6,380 years (carbon-14 ages of this magnitude are generally about 800 years younger than actual ages). Carbon for isotopic dating was obtained from carbonized root systems at the bases of lava tree casts (Peterson and Groh, 1969) and from beneath cinder deposits that extend as plumes leeward of cinder vents related to the flows (Chitwood and others, 1977). The young flows may have erupted during a much shorter period of time than the age spread indicates, perhaps as little as a few weeks or several years. All other flows are covered by Mazama ash and are older than 6,700 carbon-14 years; surface features on some flows suggest a relatively young age, perhaps 7,000 to 10,000 years, others are likely several tens or hundred of thousands of years old. ...

Cinder Cones and Fissure Vents

More than 400 cinder cones and fissure vents have been identified on the flanks of Newberry -- few other volcanoes in the world contain so many. They are concentrated in three broad zones that join on the upper part of the volcano. The eastern zone is a continuation of the High Lava Plains zone of basaltic vents and parallels the Brothers fault zone; except for cones high on the east flank, most cones in this zone appear relatively old. The northwestern zone of vents is collinear with the zone of faults on the lowermost flank that extends to Green Ridge in the Cascade Range, and the southwestern zone is collinear with the Walker Rim fault zone. Fissures and alined cinder cones generally parallel the belts in which they occur. The distribution of the vents, and particularly of alined vents and fissures, suggests that the northwest and southwest zones, and perhaps the faults that they parallel, are part of one broad arcuate zone that curves in the vicinity of Newberry's summit. Some alined cinder cones and fissure vents near the summit occur in arcuate zones parallel to the caldera rim and likely lie along ring fractures; some occur along faults whose caldera side is downdropped.

Most of the cinder cones are well preserved owing to their high porosity and consequent absorption rather than runoff of water. Larger cones are as much as 500 feet high, typical cones are 200 to 300 feet. Most are marked by summit craters and flows emerge from their bases. Cinders dispersed by prevailing winds during eruptions form aprons extending leeward from some cones such as Lava Butte (Chitwood and others, 1977).

Fissure vents consist of long ridges or trenchlike depressions formed by cinders, spatter and agglutinate flows. Small pit craters are developed along some fissure vents. ...

Shieldlike vents occur at Spring and Green Butte on the southwest flank and Green Mountain to the northwest of Newberry. They are 1 to 3 miles across, have gentle slopes, and are more faulted and older than most surficial Newberry flows.

Newberry Caldera Formation

Williams (1935, 1957) first recognized that the 4- to 5-mile-wide depression at the summit of the volcano is a caldera ...

Newberry Volcano, centered about 20 miles southeast of Bend, Oregon, is among the largest Quaternary volcanoes in the conterminous United States. ...

The youngest period of volcanism within the caldera was associated with the vent for the Big Obsidian flow. It began with eruptions that produced a widespread pumice fall that covers the southern part of the caldera and the eastern flank of the volcano (Sherrod and MacLeod, 1979). Carbon-14 ages of 1,720+/-200 (Higgins, 1969) and 1,550+/-120 (S. W. Robinson, written commun., 1978) years were obtained on carbon directly beneath the fall. ... The pumice fall was followed by eruptions that produced an ash flow that extends over a broad area between the Big Obsidian flow and Paulina Lake. It is well exposed in roadcuts near the Big Obisdian flow. Carbon-14 ages of the ash flow are 1,270+/-60 and 1,390+/-200 years (Pierson and others, 1966; meyer Reubin, IN: Friedman, 1977), with an older age (2,054+/-230 years) obtained many years ago by Libby (1952). The final event was the eruption of the Big Obsidian flow and the domal protrusion that marks its vent. Slight collapse occurred over a one-half-mile-wide area around the vent before the flow was erupted. The flow extends northward from near the outer caldera wall to near the paved road in the caldera and, in its northern part, partly filled an older pumice ring.

The eruptive sequence that culminated in the Big Obsidian Flow 1,300 years ago exemplifies several aspects of a typical rhyolitic eruptive sequence at Newberry volcano. The eruptions began with tephra showers that deposited pumice lumps and dense lava blocks as large as 1 meter (3 feet) within the caldera. ... As the eruption progressed, pyroclastic flows swept downslope from the Big Obsidian vent to Paulina Lake. The boat ramp at Little Crater Campground is excavated in these pyroclastic-flow deposits, as is the caldera road upslope from Paulina Lake. The flows entered Paulina Lake, perhaps causing secondary steam explosions and displacing water from the lake into Paulina Creek. The final stage of eruption produced the Big Obsidian Flow itself, a lava flow that moved slowly, probably advancing only a few meters or tens of meters per day as it oozed down an inner caldera wall and ponded on the caldera floor. The Big Obsidian Flow is about 1.8 kilometers (6,000 feet) long and locally thicker than 20 meters (65 feet).

The Deschutes National Forest is one of the few national forests with potential for geothermal energy development. Such potential offers a great economic opportunity for the area, while providing a long-term renewable energy resource.

Here in the Pacific Northwest and the Western Pacific, a series of volcanoes formed a "Ring of Fire" where underground heat has escaped. These volcanoes range from dormant ones, such as the Three Sisters in central Oregon and Mt. Fujiyama in Japan, to active ones, such as Mt. St. Helens in southwestern Washington and Mt. Pinatubo in the Philippines. This energy can be tapped by drilling wells, usually less than 10,000 feet deep, to bring hot fluids or steam to the surface where it can be used to generate electricity. The world's largest geothermal development is located at The Geysers near San Francisco. This facility produces about twice the amount of energy as the Bonneville Dam on the Columbia River near Portland, which produces about 1,000 megawatts, enough for a city of one million people.

Geologically young volcanoes found in our area suggest that central Oregon may contain some of the best prospects for geothermal exploration in the continental United States. One study done at Newberry Volcano estimated the energy potential to be up to 13,000 megawatts. Another study by Bonneville Power Administration estimates a 16,000 megawatt potential. ...

Newberry Volcano holds the most promise for a viable geothermal development. Located southeast of Bend, Newberry Volcano covers 500 square miles. Hot springs in the caldera have water temperatures ranging from 95 to 175 degrees Fahrenheit. In 1990, the Newberry Volcano area was designated as Newberry National Volcanic Monument. This Congressional designation restricts geothermal development within the caldera, but provides for exploration outside the Monument's boundaries. Before any development occurs, considerable effort is spent on exploration. Test wells drilled to date show that they need to be over 2,000 feet deep to reach beyond the cool ground water, and possibly go 1 to 2 miles or more deep to reach high temperatures and fluids. ...

In June 1994, the Deschutes National Forest and the Prineville District Bureau of Land Management issued a joint Record of Decision to implement the Newberry Geothermal Pilot Project. The decision was based on the environmental analysis and Final Environmental Impact Statement, and included mitigation measures and an extensive monitoring program. In October 1994, the Bonneville Power Administration released their Record of Decision adopting the same alternative as Forest Service and BLM. The approved project included exploration, development, and production operations for 14 well pads, a 33-megawatt power plant, a 115-kv transmission line, and supporting facilities on the west flank of Newberry Volcano, outside of the Newberry National Volcanic Monument. Approval from all three federal agencies allowed the operator, CE Exploration Company, to begin implementation. ...

Newberry Volcano, centered about 20 miles southeast of Bend, Oregon, is among the largest Quaternary volcanoes in thee conterminous United States. It covers and area in excess of 500 square miles, and lavas from it extend northward many tens of miles beyond the volcano. The highest point on the volcano, Paulina Peak with an elevation of 7,984 feet, is about 4,000 feet higher than the terrain surrounding the volcano.

Many of the hills on Newberry's flanks are rhyolitic domes. In addition, pumice rings, obsidian flows, and small rhyolite or obsidian protrusions occur in many places. Most of the domes form rounded hills, such as McKay Butte on the west flank, that are 100 to 500 feet high and up to 4,000 feet across. The largest dome, which forms Paulina Peak, extends southwestward from the caldera wall for 3 miles. Its very elongate outcrop suggests that it was emplaced along a northeast-trending fissure or fault; an obsidian flow crops out farther down the slope on a direct extension of the axis of the Paulina Peak dome and may have been erupted from the same buried fissure or fault. ...

K-Ar ages were determined on six rhyolite domes and flows. The ages range from 400,000 to 700,000 years, although many undated rhyolites are probably younger. Some small spinal protrusions, domes, and pumice rings on the upper southeast flank may be less than 10,000 years old. In contrast to the relative antiquity of many rhyolites on the flanks, those in the caldera are commonly younger than Mazama ash and as young as 1,400 years. ...

Paulina Peak dome extends about 3 miles southwest down the flank (of Newberry Volcano) and is about 1 mile wide. It is marked by large rills parallel to its axis that formed during expansion of the surface of the dome much as cracks form on french bread. The age of the dome is not yet know, but an obsidian flow that occurs on axis with the dome farther down the flank is 0.4 million years, and Paulina Peak dome may be similar in age. ...

Before the Ice Age, Mount Newberry formed as a shield volcano, the highest point of the Paulina Mountains, set apart from the Cascade Range to the west. This peak may have reached a height of ten thousand feet before it collapsed to form a crater. Today, the highest point of the crater is 7,897 foot Paulina Peak. ... Paulina Peak is named for a Snake Indian chief who led raiding parties against white settlers in the 1850s and 1860s.

The Newberry National Volcanic Monument, located about ten miles south of Bend in Central Oregon, is one of the nation's newest national monuments. Established by Congress in 1990, the monument will be managed to preserve for present and future generations the unique geologic landforms and many other resources in the 55,500 acre area. An additional 10,300 acres is included in special management areas.

Access to the volcano is generally excellent, with the most direct route being along Highway 97 going south from Bend. A system of roads for harvesting timber and for recreation covers all but the highest flanks. A road through the caldera and one to the top of Paulina Peak offer access to the top of the volcano. Nearly all the land of Newberry volcano is managed by the Deschutes National Forest.

"Visit A Volcano" - Newberry National Volcanic Monument

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