Chris Harkins, age 8, of Philadelphia, Pa., for his question:

WHAT MAKES THE OCEAN WAVES?

When you spend a lovely day on the beach, you can watch the tide come in and go out. Every six hours, the little waves with lacy collars wash up and down over the sand. Some people think the ocean waves are caused by the tides, but this is not so. Almost always they are made by winds blowing over the surface of the ocean.

The waves that reach the beaches are started by winds blowing over the sea. Gentle breezes make little waves. Strong winds whip up big waves  and all of those waves travel on and on. The tossing waves from huge howling storms may travel a thousand miles over the oceanAll of the everyday ocean waves are made by big or little winds. But sometimes there is a shuddering seaquake in the ocean floor.

It upsets all the water and heaves it around. This causes a great tidal wave called a tsunami  which may be wilder than any waves the winds can make.