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Ginkgo Petrified Forest State Park/Wanapum Recreational Area is a Washington state park at Vantage, Washington that includes of shoreline on the Wanapum Reservoir on the Columbia River. Petrified wood was discovered in the region in the early 1930s, which led to creation of the park as a national historic preserve.〔 The strata it lies in is identified as the Miocene Epoch of the Neogene period (15.5 MYa).〔 Over 50 species are found petrified at the site, including ginkgo, sweetgum, redwood, Douglas fir, walnut, spruce, elm, maple, horse chestnut, cottonwood, magnolia, madrone, sassafras, yew, and witch hazel. ==History== During the Miocene epoch, around 15.5 million years ago,〔 the region was lush and wet, home to many plant species now extinct. A number of these trees were buried in volcanic ash, and the organic matter in the tree trunks was gradually replaced by minerals in the groundwater; the resulting petrified wood was protected for millennia by flows of basalt. Near the end of the last ice age, the catastrophic Missoula Floods (about 15,000 BC) eroded the basalt, exposing some of the petrified wood. In prehistoric times, the Wanapum tribe of Native Americans inhabited the region along the Columbia River from the Beverly Gap to the Snake River. The Wanapum people first welcomed white strangers in the area during Lewis and Clark's expeditions across the United States.〔 They lived by fishing and agriculture, carved over 300 petroglyphs into the basalt cliffs, and may have used the petrified wood exposed by erosion for arrowheads and other tools.〔 According to documentation at the park, Wanapum never fought white settlers, did not sign a treaty with them, and, as a result, retained no federally recognized right to the land. Around 1927, highway workers noticed the petrified wood, leading geologist George F. Beck to organize excavations.〔 The Civilian Conservation Corps completed the excavation, built a small museum, and opened the park to the public in 1938. The petrified wood specimens in the museum were collected by Frank Walter Bobo, who was born March 4, 1894 in California. He moved to Cle Elum, Kittitas County, Washington. He became a "desert rat" digging petrified logs from the arid hills of Kittitas and Yakima counties. He was commissioned to collect, saw, and polish the specimens for the museum. Bobo was partially compensated by being allowed to keep one-half of the specimens he prepared while on commission. His son, Don J. Bobo, Teanaway Valley, Washington, inherited his father's collection of about one ton of petrified wood. In 1963, Wanapum Dam was completed about four miles (6 km) downstream, raising the water level of the Columbia River. A new Interpretive Center was constructed and about 60 petroglyphs salvaged from the rising water. Many of the salvaged petroglyphs are on display at the Interpretive Center. In October 1965, the National Park Service designated the Ginkgo Petrified Forest as a National Natural Landmark.〔 Petrified wood was named the Washington state gem by the state legislature on March 12, 1975.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Ginkgo Petrified Forest State Park」の詳細全文を読む スポンサード リンク
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