Exploring the Northwoods Country, Part 5: Up Close and Personal | Ely, Minnesota, USA
Taken at the location cited in Part 3 of this set.
Peering through this famous geologic site's protective chain-link fence, we get a much better view of the magnificent ellipsoidal structure of some of the boulder's pillows.
The parent basaltic lava of this big chunk of Ely Greenstone first took on this mega-lumpy form when it was extruded into the cold water of a now long-vanished seafloor about 2.7 Ma ago, during the Neoarchean era. At that point, one of the major building blocks of ancient North America, the Superior Craton (or Superior Province), was being built up by a series of terrane collisions and mountain-building events.
The oceanic crust that was the Ely Greenstone's original setting has over a vast span of time found itself locked in the heart of a great continent. For what it's worth, geologists classify this rock unit as part of the Vermilion Greenstone Belt of the Superior Craton's Wawa Subprovince.
You'll find the other photos and descriptions of this series in my Exploring the Northwoods Country album.
Exploring the Northwoods Country, Part 5: Up Close and Personal | Ely, Minnesota, USA
Taken at the location cited in Part 3 of this set.
Peering through this famous geologic site's protective chain-link fence, we get a much better view of the magnificent ellipsoidal structure of some of the boulder's pillows.
The parent basaltic lava of this big chunk of Ely Greenstone first took on this mega-lumpy form when it was extruded into the cold water of a now long-vanished seafloor about 2.7 Ma ago, during the Neoarchean era. At that point, one of the major building blocks of ancient North America, the Superior Craton (or Superior Province), was being built up by a series of terrane collisions and mountain-building events.
The oceanic crust that was the Ely Greenstone's original setting has over a vast span of time found itself locked in the heart of a great continent. For what it's worth, geologists classify this rock unit as part of the Vermilion Greenstone Belt of the Superior Craton's Wawa Subprovince.
You'll find the other photos and descriptions of this series in my Exploring the Northwoods Country album.