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Beach sand moves from a rivermouth, to the beach and then to an offshore underwater canyon. This geographic system is called a littoral cell. Streams and rivers deposit their transported sands in the form of a delta at the mouth of the river. Wave action will then smear these river deltas along the shore to form new beaches. When the waves break at an angle to the shoreline, a portion of the incoming wave energy is directed along the shore. These currents flow parallel to the shore. They are called the "longshore currents." Surfers call this the "drift." These same currents that transport a surfer down the beach from his point of entry will also move the beach sands from their initial sources at the mouths of rivers and streams. A "submarine canyon" is submerged ancient river valley that extends into the sea. These valleys were flooded underwater as ice melted during the last ice age. Now these canyons act to intercept the longshore transport. The sand flows into these canyons in periodic "avalanches" called turbidity currents. The beach sand flows into these submarine canyons where they are deposited forever. Thus, the littoral cell, from the rivermouth to the underwater canyon is a continuous loss system. There must be a continual sand supply in order to maintain a steady state of shoreline sand equilibrium. If there is not, the beach will lose sand.(Source: Surfrider Foundation's Coastal Structure Manual) Wetland Loss in the U.S. "Wetlands have been disappearing at a rapid rate through most of this country's history. The U.S. Fish and Wildlife Service estimates that 104 million acres remain of the 220 million that were here when the country was first settled. The Service's most recent national report estimated that the rate of loss between the mid-1970s and the mid-1980s was about 290,000 acres per year. More recent studies by others indicate that the rate has continued to drop, and is currently less than 100,000 acres annually. This is a significant decline from an earlier survey, from the mid-1950s to the mid-1970s, when the loss rate averaged nearly 500,000 acres per year. No estimates are available for the coastal subset." The above is an excerpt from "Coastal Wetlands," prepared by Jeffrey Zinn. This is from the Oceans & Coastal Resources: A Briefing Book, which is the Congressional Research Service Report 97-588 ENR. It's available at http://www.cnie.org/nle/mar-20/k.html. 
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"It has been estimated that if the shallow tropical seas warm by as little as one or two degrees Celsius over the next century, many coral species would become extinct (three were lost from the eastern Pacific during the El Nino event of 1982-83 alone) and some reefs might disappear altogether." 
(Source: The Diversity
of Life, by Edward O. Wilson, The Belknap Press of harvard University Press,
1992, pg. 271)
Riding inside the curl of the wave, or getting "tubed" is truly thrilling. Whether bodyboarding, bodysurfing, or board surfing, time in the green room is an exhilarating experience. Often times, there's wave spray in your face so you can't see and/or your eyes may be closed for the brief second or two that you're tubed. Or perhaps you're on the shoulder of the wave and think that you may be getting close to being tubed, but aren't sure. Can you claim it? One way of knowing is sound. If you're in the tube, the sound you hear changes dramatically. It's tough to explain, but the sound deepens and is as if you're in a very small room. When you hear it, you know it. So next time you catch a wave and think you got a tube ride, remember that if you didn't hear it, it probably didn't happen.
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