“And what of the next geological bond between the Stars and Stripes and the Union Jack?” “Next in order,” replied Mr. Brock, “comes the Lowland province, embracing the southern portion of Ontario and the valley of the St. Lawrence. It consists mainly of flat-lying palæozoic rocks, and is, so to speak, an extension of part of the State of New York. On both sides of the international boundary the mineral products are the same—namely, clay, cement, and other building materials, as well as petroleum, natural gas, salt, gypsum, and other non-metallic products. They are extremely valuable, if they do not appeal to the imagination in quite the same manner as the metallic minerals.” “The two geological areas you have dealt with so far,” I ventured to point out, “have covered only a portion of Eastern Canada.” “Exactly,” replied Mr. Brock. “But the next geological province to be considered embraces about two million square miles, or more than one-half of the Dominion. It may conveniently be called the Laurentian plateau. It runs from Newfoundland to the eastern border of Manitoba, embracing the vast territories lying north of the St. Lawrence Valley, and enclosing Hudson Bay like a huge V. It is an area of pre-Cambrian rocks, and one extension passes into New York State (where it supports some large and varied mineral industries), and another extension crosses into Michigan, Wisconsin, and Minnesota (where it provides the Michigan copper mines and the great Lake Superior iron ranges). “These pre-Cambrian rocks are remarkable for the variety of minerals they contain. Iron, copper, nickel, cobalt, silver, gold, platinum, lead, zinc, arsenic, pyrite, mica, apatite, graphite, feldspar, quartz, corundum, talc, actinolite, the rare earths, ornamental stones and gems, and building materials are found in the Laurentian plateau, and nearly all of them are being profitably mined. And since the list I have just given you is far from complete, it would perhaps be better to describe the wealth of the Laurentian plateau negatively. Diamonds have not yet been located in that geological region, though, I should add, as they have been found in glacial drift brought from that area, they undoubtedly occur there.