Trabancos River

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The Trabancos is a river in Spain that flows between the Zapardiel and the Guareña rivers, and is a tributary of the Duero river. The source of the Trabancos is in Moraña, a region in the north of the province of Ávila, near Blascomillán. The Trabancos is at an elevation of approximately 1,100 metres (3,600 ft), is approximately 85 kilometres (53 mi) long and, although its river bed is stable, only has a constant water flow during and immediately after torrential rains.

From its source in the province of Ávila, to its mouth in the village of Pollos ("Village of Chickens" in Spanish) in the Vallisoletana ("confluence of waters") region, the course of the Trabancos is markedly affected by a geologic fault originating in the Tertiary era—likely pre-Pliocene that, like most of the observed faults of that geological era, follows a NNE-SSW direction. As shown in the graph below, the fault separates material laid down during the Oligocene epoch on the right margin, from material laid down during the Miocene epoch on the left margin. The surface level represents material deposited during the Quaternary period.

Archeological research in areas that surround the Trabancos River, between the villages of Castrejón and Pollos (Valladolid province) have been compared with the specialized bibliography and the published geological charts (infra). This produced identified a sequence of river terraces as follows, on the left hand margin of the chart: TT-1 platform (the most ancient, at +35/40 meters over the flood plain); the TT-2 platform (the second one at +25/30 meters); the TT-3 platform (at +15 meters over the floodplain); and the TT-4 platform (at +10 meters, the last and most recent).

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