 Rocks of this group north of Lake Superior are the layers of the North Shore Volcanic Group and the adjoining formations of the Duluth and Beaver Bay Complexes.The North Shore Volcanics originated c. 1109-1096 mya from hundreds of individual lava flows, forming six distinct tilted and partially stacked plateaus which total more than 8,000 meters in thickness.These tilt toward the syncline under Lake Superior, as shown in the adjacent picture of the Sawtooth Mountains, the slopes of which mirror those of the shoreline rocks.