{"id":9058,"date":"2023-11-22T07:30:04","date_gmt":"2023-11-22T06:30:04","guid":{"rendered":"https:\/\/www.lakebeyond.com\/?p=9058"},"modified":"2023-11-22T07:30:04","modified_gmt":"2023-11-22T06:30:04","slug":"how-much-basalt-is-below-lake-superior","status":"publish","type":"post","link":"https:\/\/www.lakebeyond.com\/how-much-basalt-is-below-lake-superior\/","title":{"rendered":"How Much Basalt Is Below Lake Superior"},"content":{"rendered":"
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Lake Superior is located in the Midwest United States, roughly on the border of Minnesota and Wisconsin and Ontario, Canada. It is the largest of the five Great Lakes, famously referred to as “Gitche Gummi” by the indigenous Ojibwe people. A significant feature of this lake is that it is largely composed of basalt, a type of volcanic rock. <\/p>\n

Basalt is a “dark-colored, fine-grained, igneous rock composed mainly of plagioclase, pyroxene, and some olivine. It most commonly forms as an extrusive rock, such as a lava flow, but can also form in small intrusive bodies, such as an igneous dike or a thin sill.” So, how much basalt is actually underneath the lake? <\/p>\n

Scientists suggest that Lake Superior is composed of roughly 16.4% basalt. This is a significant amount considering that basalt, in comparison to other rock types, is quite rare and hard to find. According to a study from the University of Minnesota Duluth, between 1.3 to 5.3 billion cubic meters of basalt, is below Lake Superior. <\/p>\n

What makes this phenomenon so interesting is that it is a result of billions of years of volcanic activity. This is because “basaltic basement rocks, which are the oldest rocks of our continent, were the original material that made the ancient North American bedrock”. In the present day, the basalt found in this lake originates from the Midcontinent Rift System, which is a 2.7 billion year old system of dikes and faults. <\/p>\n