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Narbona Pass (formerly Washington Pass) is a pass through the natural break between the Tunicha and Chuska Mountains, an elongated range on the Colorado Plateau on the Navajo Nation. A paved road, New Mexico Highway 134, crosses the range through Narbona Pass, connecting Sheep Springs to Crystal. Known in the Navajo Language as So Sila (Twin Stars), the pass was lately named in English for Colonel John M. Washington in 1859. He was a New Mexico military governor who led an expedition into Navajo country in 1849 in which he was accused of walling up a Navajo Spring, and whose troops later shot Navajo leader Narbona. In 1992 the pass gained its current name, which honors Narbona. ==Etymology== The name Narbona Pass comes from the Navajo chief Narbona for whom the Pass was named. ==Geology== The Narbona Pass runs through the crater of the long-extinct Narbona Pass volcano, which formed from violent explosive activity. Before being eroded to their present condition, many of the Chuska-Shiprock volcanoes may have had similar explosive vent structures. The basal deposits in the crater are to thick, composed of massive lapilli tuff or tuff breccia, overlaid by layers of different deposits that indicate a series of explosive phases. These created a complex mix of sheets of volcanic ash overlaid by thick trachytic lava flows. Three basalt magma flows occurred between 27.5 and 24.3 million years ago. The crater is around across, with walls high. Chuska sandstone is exposed along the crest of the Chuska Mountains in the west of the Narbona Pass. It is the remains of the Chuska erg, a windswept sand field from the Oligocene era, about 34 million to 23 million years ago. The erg is thought to have covered about in the southeast Colorado Plateau, and was surrounded by volcanic fields of the same era. The sandstone mostly came from the Precambrian basement of central Arizona, with uranium-lead dates peaking around 1700 million years ago and 1425 million years ago. The sandstone to the west was later eroded, with being lost in the basin, but remnants remain on the mountains. 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「Narbona Pass」の詳細全文を読む スポンサード リンク
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