Scientists confirm the discovery of 40 huge holes at the bottom of Lake Michigan

NOAA's Great Lakes Ecology Research Laboratory (GLERL) has identified nearly 40 circular structures on the bottom of Lake Michigan, Live sciences I mentioned.

In 2022, NOAA researchers surveying the Great Lakes used sonar to detect unusual circular depressions at the bottom of the lake. These depressions, ranging from 91 meters (300 ft) to 183 meters (600 ft) wide, caught the attention of shipwreck hunters at the time, although scientists have only recently been able to examine them more closely.

During an expedition in August, the team discovered about 40 of these features, which are believed to be sinkholes. These formations were found about 22.5 kilometers (14 mi) southeast of Sheboygan, aligned in a line extending toward Port Washington.

“There were dozens of them in our search network,” Brendon Billaud, the shipwreck hunter who first noticed them in 2022, said in an interview with Live Science. “Most of them ranged between 500 and 1,000 feet [152 to 309 meters] Its diameter was irregular in shape.”

These gaps were likely formed by typical geological processes.

The US Geological Survey notes that “underground craters are most common in what geologists refer to as ‘karst terrain’.” “In these areas, certain types of subsurface rocks can dissolve naturally due to groundwater circulation. Dissolvable rocks include salt beds, gypsum, limestone and other carbonate formations.”

The underlying limestone of Lake Michigan helps explain the creation of these sinkholes. While their formation is straightforward, these structures are far from ordinary. Similar cenotes in Lake Huron host unique microbial communities that thrive in oxygen-poor, sulfur-rich groundwater, resembling life on Earth about 2.5 billion years ago.

“Like early Earth, Lake Huron's Middle Island Crater is dominated by microorganisms. Scientists recognize three main domains of life: bacteria, known for their diversity and adaptability; archaea, known for their ability to survive in extreme conditions and produce methane; and eukaryotes, which Includes plants, animals, fungi and protists,” states a study of Lake Huron streams.

On the bottom of the lake, bacteria form a purple mat.

“DNA analysis revealed that the majority of the purple mat is composed of Autumn Phormidium, a photosynthetic cyanobacterium. These filamentous organisms use light energy to convert dissolved carbon dioxide (CO2) into organic carbon.”

These microorganisms are found in diverse environments, from Yellowstone National Park to ice-covered lakes in Antarctica.

“We also discovered methane-producing archaea in the sediments and several eukaryotic species within the mat. While many of the DNA sequences are similar to known organisms, some represent new and perhaps undiscovered microbial life forms.”

More research is necessary in Lake Michigan to determine whether it contains similar life forms, although GLERL scientists told the Milwaukee Journal Sentinel that they believe the gaps are similar to those in Lake Huron and may provide insight into early Earth conditions.