As late as the 1870s, the interior of souhern Patagonia was practically unexplored and unmapped. The inland areas show only a few rivers, mountains and lakes, some quite inaccurately. By contrast, the coastal features are more detailed, the result of decades of hydrographic surveys.

The map also reflects the unsettled nature of the national boundary between Chile and Argentina. The broad grey line (see images) denotes roughly the cordillera of the Andes. The lands lying to the east of this line, bounded to the north by the rivers Limay and Negro, and to the east by the Atlantic Ocean, are described as "Patagonia: Eastern Chili or Colonial Territory of Magellan".