Geology Reference
In-Depth Information
structure, extending Bastendorff Beach seaward to
obscure the original configuration. Dune sands here
have been further stabilized by grass plantings.
Among the erosional processes on the coast-
line, landsliding is one of the most significant. Once a
section of land has slumped and come into contact with
the ocean, wave activity cuts away the supporting
material at the toe. A steep cliff which is even more
vulnerable to repeated sliding and erosion is produced.
Landsliding is readily apparent along 70 of the 150
miles of the northern Oregon coast as far south as
Florence. In February, 1961, a large mass of earth
began to move at Ecola State Park in Clatsop County
dumping much of the debris into the sea. Over a
period of two weeks approximately 125 acres was
carried downslope at a rate of 3 feet per day. A classic
case of coastal sliding took place near Newport when
a large block slid seaward from 1942 to 1943 taking 15
houses with it. The opening widened, breaking up the
pavement, roads, and water mains that formerly con-
nected to houses on the slumping ground. Today the
sea is attacking the seaward side of the mass, and
eventually the bulk of the debris will disappear.
Sand Spits
Sand spits partly block the entrance to a
number of rivers, and frequently the sands have nar-
rowed the opening to restrict tidal movement in and
out of the bay. Receiving sands carried on currents,
sand spits develop where a projecting headland diverts
Landslides near Newport began in 1922, but major movement occurred from 1942 to 1943 (photo
courtesy E. M. Baldwin).
