In 1501 a Portuguese expedition set out to map the coast that Cabral had claimed the year before. Andre Goncalves led it; Amerigo Vespucci sailed with it, and would later lend his own name to two continents. Three ships reached the Brazilian coast on 7 August 1501, anchoring near the place now called Arraial do Marco, roughly 45 nautical miles from the cape. The naming convention was simple and it produced the map Brazil still uses: whatever saint the church calendar assigned to the day you charted a feature, that saint got the feature. This headland went to Saint Roch, whose feast falls on 16 August - which places the naming more than a week after the ships first touched the coast, somewhere in the long, slow business of working north and west along an unmapped shore. Cabo de Sao Roque has carried the name ever since, in Portuguese and in the English of the charts that transliterated it as Cape St Roque.

Why did navigators care about a headland with no harbor? Because of where it sits on the bend. A ship crossing from West Africa toward South America is making the shortest ocean passage between the two landmasses, and the shortest passage ends at this corner. Get your latitude right and Sao Roque is the first thing you see. Get it wrong and the consequences diverge sharply, because the coast turns here: miss to the south and you run down the long eastern shore toward Recife and Salvador; miss to the north and you are into the westward-trending coast that leads to the Amazon. For centuries of Atlantic sailing, this cape was the fork in the road, the landfall that told a navigator which Brazil he had arrived at.

Up close the drama is smaller and gentler than the map implies. About six kilometers of coastal dunes run along the cape, backed by low cliffs that look out over coconut palms toward the water. A lighthouse marks the point. Offshore lie the Parrachos de Maracajau - shallow coral formations that fill at low tide into natural pools clear enough to see the bottom, protected by state decree since 2001. The reef draws far more visitors than the headland does, which is a common fate for places whose importance was mainly to people trying to avoid running into them.

Maxaranguape is a municipality of roughly 10,500 people spread across 132 square kilometers, with 20 kilometers of Atlantic coastline and about 46 kilometers of road between it and Natal, of whose metropolitan region it forms part. Around four fifths of it falls within the Atlantic Forest biome and the rest is caatinga - the thorn scrub of the Brazilian interior beginning almost at the water's edge. Rain concentrates between March and August; one May day in 2005 dropped 200 millimeters in twenty-four hours. Fishing and tourism carry the place now, and the traffic that once made the cape matter passes far offshore or higher overhead, on flight paths that still use the same corner for the same reason. It is a quiet place. It is also, on every chart of the South Atlantic ever drawn, a name in bold at the exact point where the continent turns its shoulder.