EM 1110-2-1100 (Change 1)
31 Jul 03
I
ICE AGE
A loosely-used synonym of glacial epoch, or time of extensive glacial activity; specifically of the latest period of
widespread continental glaciers, the PLEISTOCENE Epoch.
ICE FRONT
The floating vertical cliff forming the seaward edge of an ICE SHELF or other glacier that enters the sea.
ICE SHELF
A extensive sheet of ice which is attached to the land along one side but most of which is afloat and bounded on the
seaward side by a steep cliff (ICE FRONT) rising 2 tp 50+ m above sea level. Common along polar coasts (Antarctica,
Greenland), and generally of great breadth and sometimes extending tens or hundreds of km seaward from the continental
coastline.
IMPERMEABLE GROIN
A GROIN constructed such that sand cannot pass through the structure (but sand may still move over or around it).
INCIDENT WAVE
Wave moving landward.
INDIAN SPRING LOW WATER
The approximate level of the mean of lower low waters at spring tides, used principally in the Indian Ocean and
along the east coast of Asia. Also INDIAN TIDE PLANE.
INDIAN TIDE PLANE
The datum of INDIAN SPRING LOW WATER.
INFRAGRAVITY WAVE
Long waves with periods of 30 seconds to several minutes.
INLAND WATERS
Waters landward of the baseline (COASTLINE) from which the marginal seas are measured and over which
complete sovereignty is exercised. Also known as "internal waters."
INLET
(1) A short, narrow waterway connecting a bay, lagoon, or similar body of water with a large parent body of water.
(2) An arm of the sea (or other body of water) that is long compared to its width and may extend a considerable distance
inland. See also TIDAL INLET.
INLET GORGE
Generally, the deepest region of an inlet channel.
INSHORE (ZONE)
In beach terminology, the zone of variable width extending from the LOW WATER LINE through the BREAKER
ZONE. Also SHOREFACE. (See Figure A-1)
INSHORE CURRENT
Any current in or landward of the BREAKER ZONE.
INSULAR SHELF
The zone surrounding an island extending from the LOW WATER LINE to the depth (usually about 183 m;
100 fathoms) where there is a marked or rather steep descent toward the great depths.
A-40
Appendix A Glossary of Coastal Terminology
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