Continents don’t come of age all at once. Rather, they are assembled, piece by piece, through the long process of plate tectonics. Every continent has a core – or a ‘craton,’ as geologists call it – that serves as its original landmass. Onto this nucleus of a continent, new land carried along by plate tectonics eventually bumps into the craton, and becomes part of the new continent, growing it larger through successive collisions. Thus, most continents are oldest in the middle, with progressively younger parts added around the edges. North America was ‘born’ about 3 billion years ago with the assembling of the Superior Province, which makes up the bedrock in south-central Canada and north-central United States. A sequence of five events each added a new piece of land, as the young continent gained the real estate that became Manitoba, Ontario, the Great Lakes Region, and northern Minnesota. The youngest part of the original North American craton is called the Minnesota River Valley terrane, which is a chunk of land that slid into the young North American continent around 2.6 billion years ago. At the time of this tectonic collision, Minnesota and the Dakotas were home to soaring mountain ranges as landmasses collided and pushed rocks upward. Pressure and heat from the tectonic activity caused the bedrock to buckle and melt, creating liquid magma. Pockets of molten rock flowed upward within Earth’s crust, but didn’t reach the surface, so the magma didn’t erupt like a volcano. Instead, these magma pools cooled slowly while still underground, forming crystals of feldspar, quartz, and dark mica. Western Minnesota contains several of these granite intrusions, and because geology has no concern for state lines, one lone spot of granite welled up in South Dakota, not far from the Minnesota border. This was the birth of the Dakota Mahogany Granite, in what is now Milbank, S.D. The formation of Dakota Mahogany marks the last time the Midwest endured a tectonic collision. Since then, seas have advanced and retreated across the landscape, the continents have rearranged themselves in different parts of the globe, and vast ice sheets grew, then melted, then grew again, over the course of several ice ages. After 2.6 billion years of erosion, the Midwest’s former mountain ranges have been worn down, leaving the landscape mostly flat. Through all of this, Dakota Mahogany sat patiently, waiting for its day in the sun.