Scott, K. and Tucker, D., 2004, Natural dams and floods of legend at Mount Baker volcano-evidence from the stratigraphic record of volcanic activity during the Sherman Crater eruptive period (AD 1843 to present):GSA Abstracts with Programs, v. 36, n. 5, p. 377

Natural dams and floods of legend at Mount Baker volcano-evidence from the stratigraphic record of volcanic activity during the Sherman Crater eruptive period (AD 1843 to present)

Initial products of the Sherman Crater eruptive period were the tephra set YP in 1843 and the multi-branched Morovitz Creek Lahar in 1845-1847. Deposits were distributed over much of the SE flank of the volcano, drained by the Baker River, a major tributary of the regional Skagit River drainage. The pale-colored, altered-lithic ash fragments contributed to the unique description, by pioneer paleohydrologist JE Stewart after 1910, of the "tree-staining flood of 1856." The dates and relative magnitudes of that flood and an even larger "Indian-legend flood of 1815" were based by Stewart on memories, recorded by early settlers in 1879 and later, of elderly Native Americans from their youth. Another legend (unknown to Stewart) attributed a large pre-settlement flood on the Skagit River to failure of a landslide dam of the Baker River. This account probably relates to damming of the river at one of two places by the Morovitz Creek lahar. Our detailed Holocene stratigraphy, and remarkable interpretations by pioneer geologist J Morovits, show the maximum height of any blockage was less than 4, m, not the >30 m of legend, and that erosion of at least one of the blockages was gradual. No significant flood on the Skagit River resulted by blockage breaching on the Baker River. We redate the1856 flood as between 1843 (the tephra age) and 1850. That minimum date is based on re-evaluation of dendrochronology-Stewart's interpretation of a 62-yr-old tree cut from a flood bar in 1922, with an assumed ecesis period of 4 yrs (yielding 1856), rather a probable minimum ecesis period on fluvial gravel in the area of >10 yrs. All the 19th century legends of pre-settlement flooding can be explained by a single, probably rainfall-runoff flood between 1843 and 1850. No account is of more than one flood and the earliest and best known account (1879) describes "the one flood of Indian legend." We also doubt a large 1815 flood, based on possibly excessive antiquity given Native American accounts, in particular the example of what we know to be the 1843 eruption of Sherman Crater eruption that was interpreted as in 1877 and later as occurring ca. 1810.