Stratigraphic Unit No. 5. Interpreted deposit type: co-pyroclastic flow tephra fall. Thickness: 75 cm. Grain size: medium to fine ash; randomly distributed 1-2 mm to 1 cm pumice lapilli. Bedding: massive. Sorting: well to moderately sorted. Juvenile clast type: tan (pumice-like clasts, yet still poorly vesiculated). Remarks: coarsest (1 cm) pumice lapilli. Munsell color-wet: 10YR 4/2. Munsell color-dry: 10YR 2/2. Grain shape: pumice lapilli-subround to round. Age: 840+/-60 yr. B.P. >1953.
Characterization and discrimination of Holocene tephra-fall deposits, Mount Spurr volcano, Alaska
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