Lakes are bodies of water that give life and enjoyment to people and animals alike. They are often beautiful, scenic destinations. What are lakes, and how did they get here? Read on to learn more!
A True Natural Wonder
If you’ve ever spent time at a lake, you know there are plenty of activities to enjoy. Swimming, canoeing, waterskiing and fishing are just a few. Looking out over one of these bodies of water, you might wonder: How did this lake get here? Where did all this water come from? Found on every continent in the world, lakes are unique natural wonders! Join us as we learn more about lakes and uncover their origins.
What Defines a Lake?
Lakes are defined as bodies of water surrounded on all sides by land. They can be quite small, like a secret fishing hole tucked deep in the woods. Lakes can also be enormous, like the Great Lakes of the U.S.. In fact, some giant bodies of water that we call seas are technically lakes (more on that later)!
In most lakes, the water temperatures separate into distinct layers. If you’ve swum in a lake during the summer, you may have noticed that the top layer of water is quite warm. Why is that? The hot sun beats down on the top of the water, warming it to a cozy temperature. However, the sunlight can’t reach down to the depths, leaving you with chilly toes! This temperature layering is called thermal stratification.
Fresh or Salty?
Lakes are typically freshwater, but not always. This brings us to some extreme lakes of the salty type. Ever heard of the Great Salt Lake in Utah? It’s the largest saltwater lake in the Western Hemisphere. It’s even saltier than the ocean. How about the Caspian Sea between Europe and Asia? It’s another enormous body of saltwater that’s truly a lake: the largest lake in the world!
What makes these lakes salty? Many lakes are fed by rivers, and the rivers bring small amounts of natural salt. There are also outlets where the water flows out of the lake. This gradually refreshes the water, like re-filling your wading pool as water splashes out. Salty lakes are different, because water does not flow out. Water from the lake evaporates, but the salt stays behind. This makes for very salty water!
How Are Lakes Formed?
Now back to one of our original questions: Where did lakes come from? Many freshwater lakes were formed as a result of glacial movement. Over thousands of years, huge glaciers moved slowly over the earth, carving out soil like a giant ice cream scoop. This left behind huge basins, like giant bowls. As the glaciers melted, the water filled the basins and voila! Lakes were formed.
In other cases, tectonic plate movement under the earth’s crust created giant cracks in which lakes formed, like the Dead Sea (yes, it’s a lake, too!). Other lakes known as oxbow lakes are formed when a meandering river floods and pools in one place. And did you know that volcanoes can create lakes? Sometimes when a volcano erupts or collapses, it leaves behind a large crater called a caldera (think ‘cauldron’). Over the years, this caldera fills with rain and melted snow and creates a deep lake, such as Crater Lake in Oregon.
Lakes are bodies of water surrounded on all sides by land, and they exhibit thermal stratification. Lakes can be fresh or salty and vary greatly in size and depth. Lakes can be formed by glacial and tectonic plate movement, flooded rivers and volcanic craters.