Is This an Ocean or a Lake?

Is This an Ocean or a Lake?. Indiana Dunes National Lakeshore. Here you can surf the waves, stroll the shoreline, and see the dunes, but you are not at the ocean. Lake Michigan is part of the world’s largest fresh water system–the Great Lakes. Extending northward for 307 miles and averaging 118 miles from east to west, it is, indeed, a great lake. , , This vast body has 1,180 cubic miles of water, enough to cover 48 states two fee deep. For the millions of people living within its watershed, it is a valuable source of fresh drinking water. , , What’s the Difference? , Lakes:

• made of fresh and salt water.
• surrounded by land.
• larger and deeper than ponds and fed by rivers.
• considered temporary, in geologic terms.

Oceans:

• large, continuous bodies of salt water.
• responsible, through evaporation, for rainfall on land.
• affect wind and climate patterns.
• cover nearly 71 percent of the Earth’s surface.

(Graphic Caption) , Imagine how this landscape looked 14,000 years ago, when a mile-thick sheet of ice covered the region. As the glacier slowly melted it left depressions in the earth that gradually filled with water. These huge basins are called the Great Lakes.