Nechí River

Nechí River
Country	Colombia

Nechí River is a river of northwestern Colombia. It flows into the Cauca River. Nechí River rises in the municipality of Yarumal, and serves as a boundary between the municipalities of Antioquia, Campamento, Angostura, Anorí, Yarumal, Valdivia, Tarazá, Cáceres, Zaragoza, El Bagre, Caucasia and Nechí. Significant gold deposits have been found in the area.

Nechí in the Yamesí language takes its name from Ne which means "gold", and Chi which means "river". This is because there are significant mineral reserves in the area, including gold.

The river is about 7 degrees north of the equator. The Porce River, is a south tributary of the Nechi.Angostura is a municipality situated where the Nechi river breaks through the Andes. The weather is torrid and the humidity very high, even in the dry season when the temperature ranges between 24 and 35 °C (75 and 95 °F).

Mining properties of the area lie in an oval basin surrounded by crystalline rocks. This basin has been cut through by the Nechi river, which separates the properties. Within this basin are flat tables of gravel deposits whose edges form terraces. The bedrock of each of these gravel benches is clay, either red or blue according to exposure, in which are included beds of peat or brown coal. Each of these gravel benches is a re-concentration of the bench above it, and represents a former stationary level of the river. California Hill is a remnant of the upper bench. Below this was a lower bench whose bedrock stood above water-level. These two benches have been nearly removed by erosion and ancient workings. The third bench, partly submerged, forms the greater portion of the higher dredging ground. The fourth bench is that being dredged now and is nearly submerged. The outer and higher bench gravel is on the clay which lies directly upon the rim rock, but toward the centre of the basin, where there are lower layers of gravel, is assumed to be bedrock. The gold here is of fairly uniform sized thin flakes. There is very little black sand.

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Wikipedia