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Text Description: Stratigraphic Unit No. 11d. Interpreted deposit type: tephra fall. Thickness: 8.5 cm (132 cm cumulative; unit broken into 7 subunits based on bedding characteristics). Grain size: fine lapilli to coarse ash. Bedding: normally graded. Sorting: poorly sorted. Juvenile clast type: tan (pumice-like clasts, yet still poorly vesiculated), and black-glossy (dense, scoria-like clasts). Remarks: representative sample. Munsell color-wet: 10YR 2/2. Munsell color-dry: N 6.5. Grain shape: angular. Age: >3930+/-40 yr. B.P. References:  Characterization and discrimination of Holocene tephra-fall deposits, Mount Spurr volcano, Alaska |
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