Sandra Davis, age 13, of Peterborough, Ont., for her question;
Which is the deepest ocean?
Seen from the moon, our earth would‑look like a very watery world. Almost three quarters of its surface is covered by seas. When the Pacific is turned to face the moon, our planet would seem to be almost all water. For the waist of the wide pacific reaches almost half way around the world. Put we know that this surface picture does not give a true idea of the ocean deep below. The floor of the ocean has more ups and downs than the land.
The deep ocean usually begins far from land. Four deep basins are gouged into the crust of earth and hold most of the seawater. The Arctic basin covers the north pole. The Indian Ocean basin begins off southern Asia. The Atlantic and Pacific basins begin near the Arctic Circle and cut right down to the Antarctic. Here, their waters merge with the Indian ocean to sweep around the entire world as the Antarctic Ocean.
The continental shelves join the land masses to the deep ocean basins. They are sloping plains of shallow waters, teeming with life, Off Canada the shelf is about 100 miles wide, off California about 20 miles and off Florida the shelf is but a .sill a few feet wide.
The deep ocean begins where the continental shelf ends. Usually there is a sheer cliff 13,000 to 30,000 feet high. At this point the depth of the ocean floor plunges from 400 to 500 feet to the black abyss two to five miles below. Arid the floors of the deep ocean basins are more varied than the highest mountains and lowest valleys on the dry land. This underwater geography is not yet fully charted. Measuring by echo sounding is new and the job is a big one.
He can estimate the average depths of the oceans, however. The small Arctic Ocean, 58 million square miles in area, averages 3,963 feet, almost 3/4 of a mile, in depth. The Indian Ocean, almost nine tenths the area of the Atlantic, averages 13,002 feet, nearly 2 and a half miles in depth.
The stormy Atlantic covers an area of 31,830,700 square miles. Its average depth is average depth is 12,8'74 feet, not quite as deep as the smaller Indian Ocean. The biggest ocean is the Pacific ‑ over twice the area of the Atlantic. All the dry land in the world could be dug red into the Pacific Ocean without a ripple. Its vast basin and surrounding shelves hold half the seawater on the entire earth. The newest average depth estimated for the Pacific is 14,052 foot, almost 2 3/4 miles, making it the deepest as well as the largest ocean.
Taken together, the average depth of all the oceans is between 24 and 21 miles. But valleys in the ocean beds are far deeper than the average depths. A trench called the Milwaukee Deep in the Atlantic floor off Puerto Rico is over 30,000 feet deep. A trench off Mindinao in the Pacific is 34,580 feet deep enough to dunk Mr. Everest with over 1.1 miles of water above its proud crown.