Stratigraphic Unit No. 11b. Interpreted deposit type: tephra fall. Thickness: 5.5 cm (132 cm cumulative; unit broken into 7 subunits based on bedding characteristics). Grain size: coarse to medium ash bound by fine ash stringers. Bedding: massive unit bound by clay/silt stringers. Sorting: well sorted between stringers. Juvenile clast type: black-glassy (dense, scoria-like clasts). Remarks: representative sample. Munsell color-wet: 10YR 2/2. Munsell color-dry: 10YR 4/2. Grain shape: angular-subround. Age: >3930+/-40 yr. B.P.
Characterization and discrimination of Holocene tephra-fall deposits, Mount Spurr volcano, Alaska
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