Why Two Northern Places Trade

Two Places, One Northern Exchange

In a snowy northern interior, Northwind Basin lies west of Ravenrock Shelf. A river begins in high ground near the shelf and winds through the basin. Low hills surround the basin. Its broad, level floor is sheltered from some strong winds, while the higher shelf is more exposed.

People built the main Northwind settlement near a gentle bend in the river. The flat ground gives families room for homes, storage sheds, and a road. The nearby spruce forest provides timber and fuel. In warmer months, small boats can carry goods on the river. In winter, when the ice is safe, sled teams can travel along its broad, fairly smooth surface.

Ravenrock Shelf has a different set of useful features. Its rocky ground contains a quarry that provides cut stone. The shelf has few level spaces, so many homes stand in a sheltered notch beside the quarry. A narrow road called Raven Pass crosses the ridge toward Northwind. The pass is steep, and wind can pile snow across it. Sleds and wagons usually move more slowly there than on the flatter routes.

The two places trade because their resources differ. Northwind sends timber to Ravenrock, while Ravenrock sends stone to Northwind. Traders choose routes according to land and weather. When the river ice is safe, it offers a smooth winter path between the places. When ice is unsafe, traders can use the valley road or the harder route through Raven Pass. The exchange near the river bend connects these routes. In one winter week, traders recorded the loads that arrived by each route in the graph.