The Causes Of The Sioux Quartzity

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IV. Mesoproterozoic
Depending on what part of Minnesota you would have been in during the Mesoproterozoic there would have been different things occurring. In Northern Minnesota, the greenstones and granites were eroding away along with the gneiss and granite in north central Minnesota. This erosion created a lot of quartz, which was eventually turned into quartz sandstone (Ojakangas, and Matsch 1982). These quartz sandstones are the Sioux Quartzite of southwestern Minnesota, the Nopeming quartzite of the Duluth area, and the Puckwunge formation of north-easternmost Minnesota. In other parts of the state, you would have seen a Mid-Continent Rift Forming.
The Sioux Quartzite is somewhere between 1.7 and 1.6 billion years old (National Park Service 2014). The Sioux Quartzite is mostly made up of quartz, but the unique variety called the Pipestone or
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The basalt along the North Shore came from the Mid-Continent Rift. There has been many different basalt lava flows in the North Shore. In Two Harbors, the basalt that would have been on the top of the lava flow is littered with amygdules. An amygdule is just a gas bubble or vesicle that has been filled with minerals. The basalt under the amygdaloidal basalt formed at the bottom of the lava flow because it doesn’t have any amygdules. In Gooseberry Falls, the amygdaloidal basalt is at the bottom of the falls and the basal basalt is at the top of the falls. The amygdaloidal basalt is more easily eroded compared to the basal basalt, and this is why you have the waterfalls. The split rock lighthouse also has amygdaloidal basalt and basal basalt near it. The amygdaloidal basalt is closer to the lighthouse. There is some fine grained sandstone in between the basalt. There are also some anorthosite xenoliths present in the basalt. The lighthouse sits on top of an anorthosite dike. All the basalt along Lake Superior dips toward the

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