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Text Description: Only found at Site A of Chester Bluff. The GI tephra is semi-continuous across Site A, forming pink pods up to 10 cm thick and 30 cm long, and reworked with up to 60 cm of vertical relief. GI is rarely associated with an organic-rich silt unit, comprising a reddish-brown organic layer interbedded with calcareous gray silt and woody lenses up to 2 cm thick. More commonly GI is reworked within deep-red loess that may be a weathered horizon (Bw). Low vesicular pumice, bubble-walled and tri-cuspate shards. Contains brown glass. The composition reported was calculated from analyses of six samples: UT1872, UT1871, UT1743, UA1055, UA1056, and UA1077. References: ![]() ![]() |
StationID | Latitude | Longitude | Geologist | DateVisited | Age Info | Volcano | Eruption | Location Description | Text Description | Sample ID | Sample Type 1 | Sample Type 2 | Final Unit | Material | Coeff | SiO2 | TiO2 | Al2O3 | FeOT | MnO | MgO | CaO | Na2O | K2O | P2O5 | Total-majors | REF majors | METH majors | Fe2O3/Fe203T orig | FeO/FeOT orig | Volatiles csv | METH volatiles | Cs | Rb | Ba | Sr | La | Ce | Pr | Nd | Sm | Eu | Gd | Tb | Dy | Ho | Er | Tm | Yb | Lu | Y | Zr | Nb | Hf | Ta | Pb | Th | U | Sc | V | Cr | Fe | Co | Ni | Cu | Zn | Ga | Mo | As | Na | K | Ref trace1 | METH trace1 | Rb | Ba | Sr | La | Ce | Nd | Sm | Eu | Gd | Dy | Er | Yb | Lu | Y | Zr | Nb | Pb | Th | U | Sc | Ti | V | Cr | Ni | Cu | Zn | Ga | Ref trace2 | METH trace2 | Light csv | Halogen csv | other major csv | other lile csv | other ree csv | other hfse csv | other hpe csv | other tm csv | other misc csv | |
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Jensen_2008_Chester_Bluff | 65.38 | -142.66997 | Jensen, B. J. L. | Chester Bluff is located in Yukon Charley Rivers National Preserve (YCNP) in east-central Alaska, on the northwest bank of the Yukon River directly upstream from its confluence with the Charley River. It is a terrace comprising a series of individual bluffs dissected by gullies that extend laterally for about 3 km. The south-facing bluffs are dry and substantial excavation (>2m) is needed to reach frozen sediments. Chester Bluff can be broadly differentiated into four units. The base of the bluff is a bedrock terrace exposed up to ~10 m above river level, composed of argillite, part of the Cretaceous Biederman Formation. Deposited on the terrace are 8-10 m of paleo-Yukon River gravel, which are overlain by 5-10 m of sand and silt rhythmites with minor gravel and planar-bedded sand. Up to 40 m of silt, interpreted as loess and interbedded with multiple organic horizons and tephra beds, cap the sequence. Sites A through C were visited in the area and were found to host 19 distinct tephra beds. A near vertical slope at Site A prevented trench completion. Two trenches were excavated on either side of Site A to examine the lateral continuity of tephra beds. Site B was successfully logged from the top of the bluff to the upper-most sand unit associated with the flood deposits. Thick colluvium at Site C prevented completion of the trench at this site. No coordinates provided; location imprecisely georeferenced from Figure 1 in Jensen et al. (2008). | Only found at Site A of Chester Bluff. The GI tephra is semi-continuous across Site A, forming pink pods up to 10 cm thick and 30 cm long, and reworked with up to 60 cm of vertical relief. GI is rarely associated with an organic-rich silt unit, comprising a reddish-brown organic layer interbedded with calcareous gray silt and woody lenses up to 2 cm thick. More commonly GI is reworked within deep-red loess that may be a weathered horizon (Bw). Low vesicular pumice, bubble-walled and tri-cuspate shards. Contains brown glass. The composition reported was calculated from analyses of six samples: UT1872, UT1871, UT1743, UA1055, UA1056, and UA1077. | Jensen_2008_Chester_Bluff_Geophysical_Institute-P2 | Tephra Fall | Cumulate | Glass | 65.7 | 0.84 | 15.46 | 5.29 | 0.13 | 1.2 | 3.76 | 4.4 | 3.06 | 6162 | EMP | 5.29 | Cl=0.16; H2O=1.34 | EMP |
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