Cordillera Oriental

Boyacá sits on a branch of the Andes known as the Cordillera Oriental.

Few people were offering rides on Route 55, a two-lane highway that weaves into the eastern mountain range known as the Cordillera Oriental.

Dr Davies and his compadres were in Colombia, in the Serranía de las Quinchas, an area of cloud- and rain-forest in the foothills of the Cordillera Oriental that was, until a peace deal signed in 2016, part of the sphere of influence of the FARC, a group of rebels fighting to overthrow the government.

The south-east drainage basin, which is smaller and economically less important than that of the Madeira, discharges into the Paraguay and extends from the Sierras de Chiquitos south to the Argentine frontier, and from the Cordillera Oriental east to the Paraguay.

Between these and the Cordillera Oriental is an apparently confused mass of broken, intersecting ranges, which on closer examination are found to conform more or less closely to the two outside ranges.