Large outcrops of Archean granitic and tonalitic gneiss downriver from the dam just north of Biron. Access is from public parking at the north end of the dam.
Steven Dutch, Natural and Applied Sciences, University of Wisconsin - Green BayFirst-time Visitors: Please visit Site Map and Disclaimer. Use "Back" to return here.
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NW 1/4 Sec 34, T23 N, R 6 E Large outcrops of Archean granitic and tonalitic gneiss downriver from the dam just north of Biron. Access is from public parking at the north end of the dam. |
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Geologic map of the outcrops after Laberge and Weis (1968).
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View of the dam |
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The main outcrop area |
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Left and below: Looking east from the outcrop area to the dam. Below: looking along the contact between light granitic gneiss and darker tonalitic gneiss. |
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Close-up of foliated granitic gneiss |
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Close-up of foliated tonalite |
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Contact between granitic and tonalitic gneiss |
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Contact between granitic and tonalitic gneiss |
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Two ages of dikes in tonalite gneiss. |
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Banded tonalitic gneiss |
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Mafic dike cutting through granitic gneiss. |
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Differential weathering of granitic gneiss and tonalitic gneiss (darker and more weathered). Aplite dikes stand out in highest relief because of their lack of mafic minerals. |
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Differential weathering of granitic gneiss and tonalitic gneiss (darker and more weathered). |
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Chemical weathering along joint plane in tonalitic gneiss |
Laberge, G. L. and Weis, L. W., 1968; A Greenstone Belt in Central Wisconsin? 32nd Annual Tri-State Geological Field Conference Guidebook. Stop 7, pp. 20-23.
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Created 3 May 2005, Last Update 18 Apr 2007
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