EM 1110-2-1100 (Change 1)
31 Jul 03
PIER
A structure, usually of open construction, extending out into the water from the shore, to serve as a landing place,
recreational facility, etc., rather than to afford coastal protection or affect the movement of water. In the Great Lakes, a term
sometimes improperly applied to jetties.
PIERSON-MOSKOWITZ SPECTRUM
Wave spectrum typical of fully-developed deep water waves.
PIEZOMETRIC SURFACE
The level at which the hydrostatic water pressure in an aquifer will stand if it is free to seek equilibrium with the
atmosphere. For artesian wells, this is above the ground surface.
PILE
A long, heavy timber or section of concrete or metal that is driven or jetted into the earth or seabed to serve as a
support or protection.
PILING
A group of piles.
PIPING
Erosion of closed flow channels (tunnels) by the passage of water through soil; flow underneath structures, carrying
away particles, may endanger the stability of the structure.
PLACER DEPOSITS
Mineral deposits consisting of dense, resistant and often economically valuable minerals which have been
weathered from TERRIGENOUS rocks, transported to the sea and concentrated in marine sediments by wave or current
action.
PLACER MINE
Surface mines in which valuable mineral grains are extracted from stream bar or beach deposits.
PLAIN, COASTAL
See COASTAL PLAIN.
PLANFORM
The outline or shape of a body of water as determined by the still-water line.
PLATEAU
A land area (usually extensive) having a relatively level surface raised sharply above adjacent land on at least one
side; table land. A similar undersea feature.
PLEISTOCENE
An epoch of the Quaternary Period characterized by several glacial ages.
PLUNGE POINT
(1) For a plunging wave, the point at which the wave curls over and falls. (2) The final breaking point of the waves
just before they rush up on the beach. (See Figure A-1)
PLUNGING BREAKER
See BREAKER.
POCKET BEACH
A beach, usually small, in a coastal reentrant or between two littoral barriers (often rocky headlands).
A-58
Appendix A Glossary of Coastal Terminology
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