Boreal Forest Rings

 forest, region

 Upload a photo

Look at the areal photo in the link. Zoom in for a look at the rings. Four rings can be observed in the area of this polygon.

Following is from the Earth Science Picture of the Day for 26 April 2007 (link below):

"In the boreal forests of Northern Ontario and Quebec, more than 2,000 large-scale forest ring features have been found during the course of aerial photographic surveys. What causes them has been the subject of speculation since they were observed in the very first aerial surveys conducted of the region decades ago. Since the 1990s, they have been the subject of detailed ground-based research investigations. Present research indicates that there are complex electrochemical reactions between underlying metallic ore bodies and the overlying limestone, creating shallow ring-shaped depressions at the surface."
epod.usra.edu/blog/2007/04/boreal-forest-rings.html