Olympic National Park’s Kalaloch Beach 4
December 16, 2019
Photographer: Ray Boren
Summary Author: Ray Boren
A forested trail along a Pacific Ocean-side strip of Olympic National Park leads down to Beach 4, one of a sequence of access points and beaches in the Kalaloch area from U.S. Highway 101, on the state of Washington’s Olympic Peninsula. At the trail’s end is a somewhat precarious scramble over the tilted and eroded sedimentary strata of what’s called the Hoh rock assemblage (named for the nearby Hoh River and the Native American Hoh Tribe), sprinkled with disc-shaped stones. As illustrated in the photograph above, taken looking down upon the mélange, on August. 9, 2019, the hefty tumbled and rounded rocks appear to have been arrayed upon the underlying, and upended, sedimentary outcrop over time by the ocean’s tides and surf.
The coastal bluff here is composed of sand and gravel transported west from the Olympic Mountains by glaciers and streams during and at the end of the ice-age Pleistocene Epoch. The bluff also includes later marshy, fine-grained silt sediments and carbonaceous clay, which began accumulating some 70,000 years ago, and continue to do so to the present day. The beach’s wave-washed Hoh assemblage sedimentary rocks, which formed 5 to 22 million years ago in a deep ocean basin to the west, have been overturned by younger strata. They’re mostly thin-bedded sandstones, siltstones and conglomerates, mixed with fragments of other rocks and minerals. Geologists call these graywackes, ocean turbidites formed in conditions such as submarine avalanches or strong turbidity currents.
North of the Quinault Indian Reservation, Beach 4 — shown more extensively in a second photo taken on the same day — is popular at low tide for observing tidal pools, found along a series of small, rocky sea stacks. Anemones and starfish thrive in these pools. Visible about 3.5 miles (5.6 km) offshore is Destruction Island, once known as Green Island by early explorers, the largest island off Washington’s Pacific Coast.
Photo Details: Top - Camera: NIKON D3500; Exposure Time: 0.0040s (1/250); Aperture: ƒ/8.0; ISO equivalent: 110; Focal Length (35mm): 27; Bottom - same except: ISO equivalent 125.