Stratigraphic Unit No. 9. Interpreted deposit type: tephra fall, locally reworked. Thickness: 63 cm. Grain size: coarse to fine ash. Bedding: massive; AT-227, AT-228 are mottled with pods of brown lapilli pumice (AT-228) possibly reworked. Sorting: AT-211 to AT-213, well-sorted; AT-227 to AT-228, moderately to poorly sorted. Juvenile clast type: white pumice (AT-211 to AT-213); white pumice (Hayes) and black glass scoria (re-worked Crater Peak) (AT-227, AT-228). Remarks: Hayes tephra-set middle. Munsell color-wet: 5Y 6/1. Munsell color-dry: 5Y 8/1. Grain shape: angular-subangular. Age: ~3650+/-150 yr. B.P.
Characterization and discrimination of Holocene tephra-fall deposits, Mount Spurr volcano, Alaska
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