Gravity Wave, Groin, Ground Swell, Gut, Guyot: 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 gravity wave, groin, groin bay, groin system, ground swell, group velocity, gut, and guyot.

Gravity Wave
A gravity wave is a wave propagated in the surface layers of water by the tendency of gravity to maintain a uniform level. Water waves longer than 5 centimeters are usually regarded as gravity waves.

Groin
Modern English groin is an alteration (influenced by groin meaning the nose of an animal, now a British dialectal word) of Middle English grynde, from Old English grynde ("abyss"). The word is akin to Old English grund ("ground").

The original meaning of groin is the fold between the lower abdomen and the thigh. Another sense of the word is in architecture: the projecting curved line along which two intersecting vaults meet.

Extended to coastal terminology, groin denotes a rigid, relatively narrow structure built from the shore seaward for tens to hundreds of yards for the purpose of protecting the shore, as by reducing erosion or by trapping sand and other drifting sedimentary materials. Some groins have openings through them; others are solid.

Groin Bay
The beach area between two groins is called a groin bay.

Groin System
A groin system is a series of groins designed to protect a stretch of beach. Also known as a groin field.

Ground Swell
A ground swell is a broad, deep swell or undulation of the ocean, in deep water or shallow coastal water, caused by long-continued strong winds or by seismic disturbance.

Group Velocity
The velocity at which a series of similar, equidistant waves travel is called a group velocity.

Gut
Modern English gut comes from Middle English gut, from the Old English collective plural guttas. The plural form alone was used for several hundred years before the singular finally developed in standard usage. The word is probably akin to Old English geotan ("to pour").

The original meaning of gut is the entrails or a portion of them. Extended, the word denotes any narrow passage.

On a coast, a gut is a narrow waterway, such as a strait or inlet. A moving channel in generally still shallow water is also called a gut.

Guyot
The generic word guyot is derived from the surname of Arnold H. Guyot (died 1884), an American geographer and geologist.

A flat-topped seamount (submarine mountain) is a guyot.
____________________________

Encyclopaedia Britannica Ready Reference 2004. CD-ROM. Encyclopaedia Britannica, 2004.

Merriam-Webster's Collegiate Dictionary. 11th ed. Springfield, Mass.: Merriam-Webster, 2006.

Merriam-Webster's Geographical Dictionary. 3rd ed. Springfield, Mass.: Merriam-Webster, 2007.

The Oxford English Dictionary. 2nd ed. Oxford, England: Clarendon Press, 1989.