How Are Lakes Formed

Underwater Treasures

Buried treasure is all around us in Detroit Lakes, but only a few are willing to dig for it.

That’s because the trinkets and valuables are buried not in the earth, but under water.

“People would be so surprised at the things they can find in the lakes around here,” said Gary Thompson, otherwise known as “Seal”, a nickname he earned because of the amount of time he’s spent in the water.

That’s about 3,500 recreational and commercial dives over his 44-year diving career.

Thompson is the owner of Discovery Dives in Detroit Lakes.

He started out his operation 24 years ago in DL as a store called Tri-State Diving, which sells and rents diving equipment.

“People were always coming in telling me they didn’t have a dive buddy or didn’t know the good places to dive around here, so I decided to start adding these trips where we take people out and help them just enjoy a day diving,” said Thompson.

Thompson’s Discovery Dives has been taking certified divers around area lakes for 20 years.

Now, “Seal” is again getting his crew (which consists of five other divers) geared up for another summer full of underwater adventure with weekend trips starting the first weekend in June and going until Labor Day.

Although Tri-State diving and Discovery Dives operates from Carmen Lake, (located near Little Floyd Lake), the weekend excursions happen all over the area.

“We’ll take about eight to 10 people out on the boat for two tank dives,” said Thompson, “We’ll take a dive in the morning, then take a break and eat something, and then another dive after a while – it ends up being about three quarters of a day.”

“Seal” says divers can expect to “discover” an array of things in area lakes, including very old, valuable tools, fishing gear, boats, anchors, old soda and beer bottles, and even 30,000-year-old bison bones.

“I have a collection of about 100 bottles,” Thompson says, “One of them is an 1897 whiskey bottle, and another one says ‘Diamond Bottling Works, Detroit, Minnesota’ – from back when the town was just ‘Detroit.’”

Although Thompson and his fellow divers are fortunate enough to discover these historical artifacts, he encourages divers to leave them in the water for others to one day find.

In addition to old (and sometimes valuable) treasures, Thompson says the freshwater fish are fantastic to see … all 300 different species of them.

Geology – The Origin and Types of Lakes

We often talk about inland lakes, in order to distinguish them from the word “sea.”

The speed of outflow of water from a lake is so low, that a person may not even notice it, which leads to the name of standing water. Smaller lakes are called, depending on the type, pool, pond, swamp, or shallow lake. Large lakes are sometimes called “sea,” for example, Dead Sea.

Inland lakes, with a total of 2.5 million square kilometres, occupy 1.8 percent of the land surface. The largest European inland lake is Lake Ladoga in Russia. The world’s largest lake without outflow is the Caspian Sea.

Globally, the distribution of lakes is very irregular, but there are regions where there is a larger concentration of lakes. These are mainly regions that have lake plates, which were formed by glaciers (particularly during the Pleistocene), found for example in Scandinavia and North America. The lakes receive their water from river mouths, atmospheric precipitation, or even from springs on the bottom of the lake.

There are freshwater and saltwater lakes. Saltwater lakes form in places, where water has no outlet, since in such a case the water evaporates and the salt concentration increases. The saltiest lake on earth is the Dead Sea, which is about nine times saltier than the oceans.

Freshwater lakes are found in places where water can flow in and flow out, for example by means of sluices, over which the water sometimes flows. Freshwater lakes are very important for our lives. They contain 95 percent of the global freshwater supply.

Only hundred years ago, the prevalent opinion was, that the lakes are remnants of ancient seas. This theory, however, applies in the case of just a few lakes. For example, the Caspian Sea was probably connected with the Black Sea some 50 million years ago. It is possible, that Lake Ladoga, situated in Russia, formed a part of Baltic Sea. These bodies of water, separated from seas, are called residual or regressive lakes. The water of the original sea, however, is long gone, because water of every lake is totally renewed every few decades.

Many lakes formed in depressions or by sinking ground. Crater lakes are the result of volcanic processes. When the summit of a volcano collapses or is blown off, it creates a circular depression, which fills with rainwater.

Tectonic lakes are those that formed as a result of the movement of the earth’s crust, for example, trench lakes. When the earth layers reform and break apart, this creates basins, or deep trenches and kettles. Tectonic lakes are often very deep. One of this type of lakes is Baikal in southeast Siberia (it is 1620 metres deep). Blind river lakes form, when a loop of a river meander separates, forming a semi-circular lake. This type is called oxbow lake.

The field guide to geology

Lakes

Practical physiography

Textbook of limnology

Environmental sedimentology