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Date Permissions Signed

5-26-2018

Date of Award

Spring 1994

Document Type

Masters Thesis

Degree Name

Master of Science (MS)

Department

Geology

First Advisor

Kelsey, H. M.

Second Advisor

Burmester, Russell F.

Third Advisor

Suczek, Christopher A., 1942-2014

Abstract

Grain size of particles tend to become smaller in the downstream direction. Abrasion and selective transport are two sets of processes commonly accepted as explanations for observed trends in fining of sediment. Most recent studies have emphasized the effectiveness of selective transport in producing downstream fining in streams with abundant sediment supply. The contribution of abrasion to particle fining of the coarsest class of particles was investigated in Finney Creek, a high gradient mountain stream in northwest Washington that has a high incidence of sedimentation from debris slides and debris flows. Two dominant rock types comprise the coarsest bed material in the studied reach; foliated particles, which are derived from the local bedrock, and non-foliated particles, which are derived from glacial valley fill. Four distinct downstream trends of particle fining are spatially associated with sources of recent deposits of coarse clasts in the channel. While particle sizes of both rock types diminish rapidly from the debris source, overall fining trends are influenced most by the fining trend evident in the foliated class of particles. The primary fining mechanisms are different for the two rock types, and are related most strongly to the inherent durability of each rock type. Selective transport is probably most important for non-foliated particles, and active but overwhelmed by abrasion for foliated particles. Field observations and experimental abrasion studies indicate that abrasion is the dominant set of processes responsible for the reduction of sizes of foliated particles, which abrade at about 10 times the rate of non-foliated particles.

Type

Text

Keywords

Fining of sediment, Particulate fining, Debris flow

Publisher

Western Washington University

OCLC Number

1080953405

Subject – LCSH

Sedimentology--Washington (State)--Finney Creek Watershed; River sediments--Washington (State)--Finney Creek Watershed; Debris avalanches--Washington (State)--Finney Creek Watershed

Geographic Coverage

Finney Creek Watershed (Wash.)

Format

application/pdf

Genre/Form

masters theses

Language

English

Rights

Copying of this document in whole or in part is allowable only for scholarly purposes. It is understood, however, that any copying or publication of this thesis for commercial purposes, or for financial gain, shall not be allowed without the author's written permission.

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