The Canadian Shield (also called the Precambrian Shield, or Laurentian Shield, or Laurentian Plateau) is now a vast area of scenic sparsely-populated forest-covered rocky hills that was originally a region of very large mountains (the ancient Grenvilles) and some volcanic activity, but over the eons the area was eroded. Mountains have deep 'roots' and float on the denser mantle below, much like icebergs at sea. As mountains erode, their roots rise, and are slowly eroded as well. The rock that now forms the surface of the Canadian Shield was once far below the earth's surface and is some of the oldest surface rock on earth, hundreds of millions to billions of years old. The hills of the Shield contain many lakes, rivers, wetlands, and outcrops and I am fortunate to live within a fairly short drive of them. Click here for further information on the Shield.