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Our transcription: For almost a billion years, the Superior Province was almost all that existed of North America. Then, other regions were added: the Churchill Hudsonian Province, 1.8 billion years ago, the Central Province, 1.6 billion years ago, and the Grenville Province, about 1 billion years ago. In these regions geologists find rocks similar to those making up modern mountain ranges, and in the very youngest parts of North America, mountains are still growing. These observations suggest that mountain building, a process geologists call "orogeny" is an essential part of continental growth. Generally speaking, the further one travels from the craton, the younger a continent becomes, and the youngest, most rugged parts of a continent lie at the edge of the ocean. In fact, the essential key to mountain building lies in understanding this link between ocean basins and continents.
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