According to buried depth, the Yellow Rver's Paleochannels can be divided into ground Paleochannels (buried depth 0-8m) and shallowburied Paleochannels theried depth 8-50m). Each of them can be roughly divided int...According to buried depth, the Yellow Rver's Paleochannels can be divided into ground Paleochannels (buried depth 0-8m) and shallowburied Paleochannels theried depth 8-50m). Each of them can be roughly divided into three major Paleochannel belts, stretching Parallel with each other from SW to NE. Sedimentary layers of the paleochannels were mainly made up by sand levee of meanders or natural leavee deposits, and the flooding sedments were found bebeen the layers. The paleochannels in North Shadong Plain were formed in three stags; stage I (buried depth 50-15m) in later period of late Pleistocene-early period of Holocene, stag II (20-8m) in earlymiddle period of HOlocene; and stag III (8-0m) in midddle-late period of Holocene.展开更多
A landslide that probably dates to the end of the Pleistocene has been found in Sierra County. The feature consists of three sub-parallel segments, covering an area about 8 km wide and 10 km long. The head of the slid...A landslide that probably dates to the end of the Pleistocene has been found in Sierra County. The feature consists of three sub-parallel segments, covering an area about 8 km wide and 10 km long. The head of the slide deposits consists of a northeast-trending paleochannel forming an inverted topography. The paleochannel deposits contain many boulders with sizes up to 1.5 meter diameter, indicating flow rate as high as 100 m3/s. The paleochannel ridge is mostly underlain by the hidden lateral contact of the Cretaceous Crevasse Canyon Formation and by the Tertiary Love Ranch and is sharply defined by Yoast Draw valley that cuts a water gap through the 25 m high inverted ridge. The landslide body consists of Love Ranch Formation overlain by a substantial cover of Quaternary fanglomerate. A series of northwest-trending faults have influenced the landslide. The broad western upslope segment of the slide has been washed away, leaving only trace evidence of a landslide. A low slide plane angle of less than 1% slope suggests a seismic trigger.展开更多
文摘According to buried depth, the Yellow Rver's Paleochannels can be divided into ground Paleochannels (buried depth 0-8m) and shallowburied Paleochannels theried depth 8-50m). Each of them can be roughly divided into three major Paleochannel belts, stretching Parallel with each other from SW to NE. Sedimentary layers of the paleochannels were mainly made up by sand levee of meanders or natural leavee deposits, and the flooding sedments were found bebeen the layers. The paleochannels in North Shadong Plain were formed in three stags; stage I (buried depth 50-15m) in later period of late Pleistocene-early period of Holocene, stag II (20-8m) in earlymiddle period of HOlocene; and stag III (8-0m) in midddle-late period of Holocene.
文摘A landslide that probably dates to the end of the Pleistocene has been found in Sierra County. The feature consists of three sub-parallel segments, covering an area about 8 km wide and 10 km long. The head of the slide deposits consists of a northeast-trending paleochannel forming an inverted topography. The paleochannel deposits contain many boulders with sizes up to 1.5 meter diameter, indicating flow rate as high as 100 m3/s. The paleochannel ridge is mostly underlain by the hidden lateral contact of the Cretaceous Crevasse Canyon Formation and by the Tertiary Love Ranch and is sharply defined by Yoast Draw valley that cuts a water gap through the 25 m high inverted ridge. The landslide body consists of Love Ranch Formation overlain by a substantial cover of Quaternary fanglomerate. A series of northwest-trending faults have influenced the landslide. The broad western upslope segment of the slide has been washed away, leaving only trace evidence of a landslide. A low slide plane angle of less than 1% slope suggests a seismic trigger.
