Siletz Bay is a drowned river valley filled with Holocene alluvial
and estuarine sediments and is separated from the ocean by a sand
spit 3.8 km in length. Since the area was settled by white man in the
1890's, the bay has apparently experienced rapid siltation, due to
increased farming and logging. This along with the damming of the
Siletz River sloughs has altered circulation patterns in the bay.
Deflection of the Siletz River flow by the prograding Drift Creek delta
has caused 105 m of erosion since 1912 on the east side of Siletz Spit.
The ocean side of the spit suffers periodic erosional episodes separated
by periods of accretion and dune building. The most recent and
publicized erosion occurred during the winter of 1972-73 when it was
feared that the spit might be breached; one partially constructed house
was lost and three others were saved only by timely riprapping. A
sand mining operation may have aggravated the recent erosion by
disrupting the sand budget, the balance of sand additions and losses
from the beach. All of the foredune on the spit has been stabilized by
dune grass and much of it has been riprapped. The long term effects
of stabilization and riprapping are uncertain. / Graduation date: 1975
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/28660 |
| Date | 13 December 1974 |
| Creators | Rea, Campbell Cary |
| Contributors | Komar, Paul D. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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