he confluence of the Sotara and
Guaitara at the point where the united streams turn westward to cut
their way through the mountains to the sea. The Sotara or upper Patia
rises on the southern slope of a transverse ridge or dyke, between the
Central and Western Cordilleras, in the vicinity of Popayan, and flows
southward about 120 m. to the point of confluence with the Guaitara.
The latter has its sources on the elevated plateau of Tuquerres and
flows north-west to meet the Sotara. The canyon of the Patia through
the Western Cordillera is known as the "Minima gorge," and has been
cut to a depth of 1676 ft., above which the perpendicular mountain
sides rise like a wall some thousands of feet more. The upper course
of the Guaitara is known as the Carchi, which for a short distance
forms the boundary line between Colombia and Ecuador. At one point in
its course it is crossed by the Rumichaca arch, a natural arch of
stone, popularly known as the "Inca's bridge," which with the Minima
gorge should be classed among the natural wonders of the world. There
is a narrow belt of low, swampy country between the Cordillera and the
coast, traversed at intervals by mountain spurs, and across this the
river channels are usually navigable. The San Juan has built a large
delta at its mouth, and is navigable for a distance of 140 m. inland,
the river flowing parallel with the coast for a long distance instead
of crossing the coastal plain. It rises in the angle between the
Western Cordillera and a low transverse ridge connecting it with the
Baudo coast range, and flows westward down to the valley between the
two ranges, and then southward through this valley to about lat. 4 deg.
15' N., where it turns sharply westward and crosses a narrow belt of
lowland to the coast. It probably has the largest discharge of water
of the Pacific group, and has about 300 m. of navigable channels,
including its tributaries, although the river itself is only 190 m.
long and the sand-bars at its mouth have only 7 or 8 ft. of water on
them. The San Juan is distinguished for having been one of the
proposed routes for a ship canal between the Caribbean and Pacific.
At one point in its upper course it is so near the Atrato that,
according to a survey by Captain C. S. Cochrane, R.N., in 1824, a
canal 400 yds. long with a maximum cutting of 70 ft., together with
some improvements in the two streams,