Irregular Waves, Island, Island Arc, Isle, Islet: Word Origins, Descriptions of Coastal Features, Processes

In the current alphabetic series of word origins and physical descriptions of coastal features and processes, here are irregular waves, island, island arc, island chain, isle, and islet.

Irregular Waves
Waves that have variable heights and random wave periods (times between consecutive wave crests passing a given point) are called irregular waves. Most wind-induced waves are irregular waves.

Island
Modern English island is an alteration (influenced by Old French isle) of the earlier form iland, from Middle English iland, from Old English igland, a combination of ig ("island") and land ("land"). Igland is akin to Old Norse eyland. Ig is akin to Old English ea ("river") and Latin aqua ("water").

A tract of land smaller than a continent and surrounded by water is an island. Islands are located in oceans, seas, lakes, and rivers.

A group of islands is known as an archipelago, from Archipelago ("Aegean Sea"), from Italian Arcipelago ("Aegean Sea," literally "chief sea"), from Italian arci- ("original, primary") and Greek pelagos ("sea").

A continental island is an unsubmerged, but entirely water-surrounded, part of a continental mass. Greenland, the world's largest island, is a continental island.

Oceanic islands result from volcanic activity, with lava piling up from the ocean floor till it rises above the surface of the water. The lava piles forming Hawaii, for example, reach as high as 32,000 feet above the ocean floor.

Island Arc
An island arc is a long. curved chain of islands associated with volcanic activity. A well-known example is the Aleutian-Alaska Arc.

Island arcs usually consist of two parallel rows of islands, the inner row being a string of volcanoes and the outer row being nonvolcanic islands. When the chain has a single arc, many of the individual islands are volcanically active.

Generally, an island arc has a landmass or a shallow sea on its concave (inner) side and a deep-sea trench on its convex (outer) side.

Island Chain
A group of islands forming a line is called an island chain.

Isle
Modern English isle comes from Middle English isle, from Old French isle, from Latin insula, probably from in ("in") plus -sula (akin to Latin salum, "sea," and sal, "salt").

An isle is an island, especially a small island.

Islet
The English word islet comes from Middle French islette, a combination of isle ("island") and the diminutive suffix -ette.

Islet is another word for a small island.
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