It stands on a mound of calcareous tufa, containing great numbers of fossil shells, the most recent of which resemble those found in the marly tufa close to the coast.

The fort stands on the south side of the town, on a high perpendicular bank overhanging the Coanza.

This river is here a noble stream, about a hundred and fifty yards wide, admitting navigation in large canoes from the bar at its mouth to Cambambe, some thirty miles above this town.

There, a fine waterfall hinders farther ascent.

Ten or twelve large canoes laden with country produce pass Massangano every day.