The Willamette Meteorite, officially named Willamette and originally known as Tomanowos by the Clackamas Chinook Native American tribe, is an iron-nickel meteorite found near Oregon City in the Willamette Valley of the U.S. state of Oregon. The meteorite is the largest one found in the United States. Euro-American society became aware of its existence in 1902, and for a long time it was seen as the sixth largest meteorite in the world. However, with new samples such as El Ali and Gancedo being discovered, the Willamette is no longer in the top ten largest meteorites in the world. There was no impact crater at the discovery site; researchers believe the meteorite landed in what is now Canada or Montana, and was transported as a glacial erratic to the Willamette Valley during the Missoula Floods at the end of the last Ice Age (~13,000 years ago). It has long been held sacred by indigenous peoples of the Willamette Valley, including the federally recognized Confederated Tribes of the Grand Ronde Community of Oregon (CTGR). The meteorite is on display at the American Museum of Natural History in New York City, which acquired it in 1906. Having been seen by an estimated 40 million people over the years, and given its striking appearance, it is among the most famous meteorites. In 2005, the CTGR sued to have the meteorite returned to their control, ultimately reaching an agreement that gave the tribe access to the meteorite while allowing the museum to keep it as long as they are exhibiting it.
Etymology The Clackamas Chinook called the meteorite t’əmanəwas, translated as "spirit power". This name is still used today by the Confederated Tribes of the Grand Ronde, which includes descendants of the Clackamas Chinook and is considered that group's legal successor. Alternate spellings including Tomanowos and Tamanowas.
Physical characteristics and formation
The Willamette Meteorite weighs about 34,200 pounds (15,500 kg). It is classified as a type III iron meteorite, being composed of over 91% iron and 7.62% nickel, with traces of cobalt and phosphorus. The approximate dimensions of the meteorite are 10 feet (3 m) tall by 6.5 feet (2 m) wide by 4.25 feet (1.3 m) deep. Most iron meteorites like Willamette have originated from the differentiated core of planetesimals or asteroids that collided with another object. Willamette has a recrystallized structure with only traces of a medium Widmanstätten pattern; the result of a significant impact-heating event on the parent body. The Willamette Meteorite contains higher concentrations of various metals that are quite rare in Earth's crust. For example, iridium, one of the least abundant elements in Earth's crust, is found in the Willamette Meteorite at a concentration of 4.7 ppm, thousands of times more concentrated than in the Earth's crust.
Emplacement and erosion
The lack of an impact crater at the discovery site was only explained after the 1920s, with the new understanding about the Missoula Floods, one of the largest floods documented. These floods were caused by the collapse of an ice barrier during the last deglaciation. The meteorite presumably landed on an ice cap in what is now Montana or western Canada, and was dragged by the glacier ice to the vicinity of an ice barrier that formed across the Clark Fork River. This barrier had ponded a huge amount of water at Lake Missoula right at the time when the meteorite reached the area and the ice barrier became unstable and was breached. The resulting flood involved up to 10 million cubic metres (350 million cubic feet) per second of water discharge, with large blocks of ice rafting down the Columbia River and the Willamette Valley at the end of the last Ice Age (~13,000 years ago). Some of these ice rafts included boulders (known as 'glacial erratic' by geologists) like the Willamette meteorite, which eventually sank in the flood waters and settled where they were found by humans. The deep crevasses of the meteorite resulted from both its high-speed atmospheric entry and its subsequent weathering. Exposed to the elements for thousands of years, rainwater interacted with the mineral troilite, resulting in a form of sulfuric acid which slowly dissolved portions of the meteorite. This resulted in the gradual development of the hollows that are visible today.
Modern history In 1902, Ellis Hughes was the first European settler to recognize the meteorite's significance. At that time, the land was owned by the Oregon Iron and Steel Company. Hughes attempted to claim ownership of the meteorite, and secretly moved it to his own land. This involved 90 days of hard work to cover the 3⁄4 mile (1,200 m) distance. The move was discovered, and after a lawsuit, the Oregon Supreme Court held that Oregon Iron and Steel Company was the legal owner. According to Native American witness who testified in defense of Hughes at the trial, the meteorite had already been owned by their ancestors long before Hughes found it on the neighboring property, and that being sent up the hill to the stone on dark nights had been a rite of passage for young men of their culture, while their warriors would seek success in battle by dipping their arrows into rainwater collected in the stone's hollows.
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