|
Beneath the surface of the ocean are miles and miles of high mountains and plunging
chasms that dwarf the overland’s most famous canyon, the Grand Canyond of the Colordo
River. Instead, the greatest canyons on earth are found below the Bering Sea between
Siberia and Alaska. Here, seven canyons exist together. Among them are the 240-mile-long
Bering Canyon, the 60-mile-wide Navarin Canyon, and the 9,000-foot-deep Zhemchug Canyon.
The Grand Canyon, in contrast, is only 10 miles wide and mile deep, winding 250 miles
through Arizona.
They were created 75 million years ago when slow movement of the crust plates created
a broad shelf 8,500 feet above the ocean floor from Alaska to Siberia. Today, the shelf
forms the bed of the northern half of the Bering Sea, the part exposed as dry land when
ice ages lower the level of the oceans. During one of these dry-land periods, the
shelf’s edge began to crack and erode. Rivers flowing across the plain also cut into
the sea floor and deposited tons of sediment at its outer edge. When the sea level rose
again, the ocean waves and currents crashed with the shallow seafloor. Gullies widened,
sediments were weakened, and gigantic landslides and mudflows swept down its slopes.
Some 1,400 cubic miles of sediment and rock were removed in the process, helping to
create Zhemchug Canyon.
|
![[forces of nature]](../fon.gif){kind=small}
![[heading]](head.gif)
![[images]](images.jpg)
