Tides are the rise and fall of sea levels caused by the combined effects of gravitational forces exerted by the Moon, Sun, and rotation of the Earth.
Some shorelines experience two nearly equal high and low tides each day, called a semi-diurnal tide. Some locations experience only one high and low tide each day, called a diurnal tide. Some locations experience two uneven tides a day, or sometimes one high and one low each day; this is called a mixed tide. The times and amplitude of tides at a locale are influenced by the alignment of the Sun and Moon, by the pattern of tides in the deep ocean, by the amphidromic systems of the oceans, and the shape of the coastline and near-shore bathymetry.
Tides vary on timescales ranging from hours to years due to numerous influences. To make accurate records, tide gauges at fixed stations measure the water level over time. Gauges ignore variations caused by waves with periods shorter than minutes. These data are compared to the reference (or datum) level usually called mean sea level.
While tides are usually the largest source of short-term sea-level fluctuations, sea levels are also subject to forces such as wind and barometric pressure changes, resulting in storm surges, especially in shallow seas and near coasts.
Tidal phenomena are not limited to the oceans, but can occur in other systems whenever a gravitational field that varies in time and space is present. For example, the solid part of the Earth is affected by tides, though this is not as easily seen as the water tidal movements.
Seal Rock State Recreation Site is a state park in the U.S. state of Oregon, administered by the Oregon Parks and Recreation Department.
Seal Rock is an unincorporated coastal community in Lincoln County, Oregon, United States, between Newport and Waldport on U.S. Route 101.
The community of Seal Rock is named for the Seal Rocks, a ledge of partially submerged rocks that parallel the shore for about 2.5 miles (4.0 km).In Chinook Jargon the area was called Seal Illahe, meaning “seal place” or “seal home”, while “Seal Rocks” is what the locality was called in pioneer times, when it was an early resort community.The name “Seal Rock” appears to refer to the one large rock, about 20 feet (6 m) above water, that was formerly where hundreds of seals and sea lions would rest.
Seal Rock was the terminus of the Corvallis & Yaquina Bay Wagon Road, which was the first road to reach the Oregon Coast from the Willamette Valley.The town of Seal Rock was platted in 1887 and three blocks of hotels were built, but development lagged and the assets of the road company were transferred to the promoter of the Oregon Pacific Railway, T. Egenton Hogg.Seal Rock post office was established in 1890.
Seal Rock State Recreation Site is a day-use site that includes tidepools and a stretch of beach.
Seal Rock is also the name of an address-restricted archaeological site in the vicinity that is listed on the National Register of Historic Places.