Ontonagon Sandstone and Hills

There is a single factor that can define the majority of the water flowing in Ontonagon County - sandstone. Underneath the red clay soil much of the county is resting on the smooth, grainy rock, defining many of the riverbeds and waterfalls here. The Trap Hills, extending southwest from the copper-bearing Keweenaw Ridge, also create a number of small drops over the volcanic rocks. Most of this county is dominated by the Ontonagon River flowing over the smooth sandstone, a creamy brown flow sluggishly winding a slow way to Lake Superior.