Block · one region of the page, as the scanner read it. It may hold a whole story, part of one, several, or an advertisement; stitching blocks into articles is the next step. Text is supplied OCR.
Page 3 · column 3 of 9 · from the scan, no model involved
Beaches Vanish as
Sand Drifts Away
Some people going to their favorite beach this summer may be surprised to find it has vanished. The ocean may have carried the sand away, leaving behind a mud fiat, a strip of rubble, or a bluff shored up with concrete or sandbags by desperate residents.
But hope is growing that more beaches can be saved, the National Geographic Society says. Engineers are learning more about the natural forces that destroy beaches; the same knowledge can be used to create beaches.
To study how sand may leave a beach, investigators have tagged grains with radiation or fluorescent paint.
Sand Is Fickle
A beach may seem motionless to vacationers, but the sand is almost constantly shifting. The grains tend to drift steadily in one direction. A beach can survive only if it receives a constant supply of new sand. Curiously, most of this sand comes from the land, not the sea. Erosion and rain grinds mountain boulders into tiny chips of quartz and feldspar. Streams and rivers wash the bits to the sea.
The smallest pieces, known as silt, settle at river mouths to form deltas. Ocean currents carry larger pieces-sand--along the coasts and deposit them on the shoreline.
Beaches starve for sand when a nearby river no longer delivers the supply it needs to replenish losses. The construction of a dam upstream to control floods and conserve water may destroy a beach hundreds of miles away. The sand from the mountains piles up against the dam and never reaches the starving beach.
To hold the sand on their
91.1%