Erosion surface in the context of "Cyclothem"

Coastal erosion is the loss or displacement of land, or the long-term removal of sediment and rocks along the coastline due to the action of waves, currents, tides, wind-driven water, waterborne ice, or other impacts of storms. The landward retreat of the shoreline can be measured and described over a temporal scale of tides, seasons, and other short-term cyclic processes. Coastal erosion may be caused by hydraulic action, abrasion, impact and corrosion by wind and water, and other forces, natural or unnatural.

On non-rocky coasts, coastal erosion results in rock formations in areas where the coastline contains rock layers or fracture zones with varying resistance to erosion. Softer areas become eroded much faster than harder ones, which typically result in landforms such as tunnels, bridges, columns, and pillars. Over time the coast generally evens out. The softer areas fill up with sediment eroded from hard areas, and rock formations are eroded away. Also erosion commonly happens in areas where there are strong winds, loose sand, and soft rocks. The blowing of millions of sharp sand grains creates a sandblasting effect. This effect helps to erode, smooth and polish rocks. The definition of erosion is grinding and wearing away of rock surfaces through the mechanical action of other rock or sand particles.

The Moenave Formation is a Mesozoic geologic formation, in the Glen Canyon Group. It is found in Utah and Arizona.

The Moenave was deposited on an erosion surface on the Chinle Formation following an early Jurassic uplift and unconformity that represents about ten million years of missing sedimentation. Periodic incursions of shallow seas from the north during the Jurassic flooded parts of Wyoming, Montana, and a northeast–southwest trending trough on the Utah/Idaho border. The Moenave was deposited in a variety of river, lake, and flood-plain environments, near the ancient Lake Dixie.

An unconformity is a buried erosional or non-depositional surface separating two rock masses or strata of different ages, indicating that sediment deposition was not continuous. In general, the older layer was exposed to erosion for an interval of time before deposition of the younger layer, but the term is used to describe any break in the sedimentary geologic record. The significance of angular unconformity (see below) was shown by James Hutton, who found examples of Hutton's Unconformity at Jedburgh in 1787 and at Siccar Point in Berwickshire in 1788, both in Scotland.

The rocks above an unconformity are younger than the rocks beneath (unless the sequence has been overturned). An unconformity represents time during which no sediments were preserved in a region or were subsequently eroded before the next deposition. The local record for that time interval is missing and geologists must use other clues to discover that part of the geologic history of that area. The interval of geologic time not represented is called a hiatus. It is a kind of relative dating.

Onlap or overlap is the geological phenomenon of successively wedge-shaped younger rock strata extending progressively further across an erosion surface cut in older rocks. It is generally associated with a marine transgression. It is a more general term than overstep, in which the younger beds overlap onto successively older beds. The opposite is offlap, in which each younger rock bed pinches out short of the full extent of the underlying older bed, typically due to a marine regression.

Robert Island or Mitchells Island or Polotsk Island or Roberts Island is an island 11 miles (18 km) long and 8 miles (13 km) wide, situated between Nelson Island and Greenwich Island in the South Shetland Islands, Antarctica. Robert Island is located at 62°24′S 59°30′W / 62.400°S 59.500°W / -62.400; -59.500. Its surface area is 132 km (51 sq mi). The name "Robert Island" dates back to around 1821 and is now established in international usage.

Much of the Coppermine Peninsula in the west of the island is made up by a perched strandflat surface that was at sea level in the past.

The Ethiopia-Yemen Continental Flood Basalts were erupted during the Oligocene. They cover an area of about 600,000 km in Yemen and Ethiopia, with an estimated volume of greater than 350,000 km. They are associated with the Afar Plume and the initiation of rifting in the southern Red Sea and Gulf of Aden.

In Ethiopia flood basalts cover an old erosion surface with occasional flat areas or peneplains. Burial of old surfaces by lava has preserved laterite soils in both Yemen and Ethiopia.