Trabancos River . State Spain Length Elevation at source Provinces Ávila and Valladolid River mouth Duero River near the Villageof Pollos (Valladolid province) Elevation at mouth River - Hydrology 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 , is approximately long and, although its river bed is stable, only has a constant water flow during and immediately after torrential rains. The river's course is affected by a geologic fault, and the surrounding region has evidence of human habitation dating back to the prehistoric era.
Fluvial geomorphology 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).
The right hand margin of the designated chart depicts a gravel plateau present along the middle and final courses of the Trabancos River. The scientist Alfredo Pérez-Gonzalez named this formation "Superficie de Alaejos" ("The Plateau of Alaejos", after a nearby village). The Alaejos Plateau incorporates a number of different types of materials, including red argillic soil and a colluvium buildup of gravels with rounded stones of quartz and quartzite.
The terraces of the Trabancos River only occur on the left hand side of the valley. Their sediments overlie Miocene sediments. This is the result of a hard slope in the opposite margin, where the terrain is heavily eroded, which renders the formation and maintenance of river terraces impossible.
Of the previously mentioned river terraces, the one known as TT-4 is only visible near Narros del Castillo (Ávila). Terrace TT-3 is the best preserved of the lot; although its height on the bed of the stream is not constant, it clearly stands out on the floodplain. Terrace TT-2 is quite well preserved as well, although it has been more heavily sculptured by other small tributaries of the Trabancos River. By contrast, terrace TT-1 is greatly eroded; although some sections survive to the south of the municipality of Alaejos (Valladolid), they are very difficult to differentiate from the colluvium floor that covers the Superficie de Alaejos. Entering into land in the municipality of Pollos, the stream stops to form river terraces, cutting traversely and lowering enough (between 40 and 60 meters) to meet the terrace deposits of the Duero River.
The TT-3 platform features a very compact and thick Miocene epoch conglomerate formed of river-smoothed pebbles of quartzite, most likely cut by the Trabancos River ages ago, and cemented together by chalk and sandstone materials. While this Miocene conglomerate emerges from the banks of each river terrace, the quartzite in the conglomerate on the TT-2 platform, just northwest of the municipality of Siete Iglesias de Trabancos, likely derives from the action of the Duero River rather than the Trabancos River, as a slope in the terrain is thought to have caused the formation of an alluvial fan that deposited quartzite on the fluvial fossil river bed of the Trabancos.
The fact that the river terraces of the Trabancos River cut and cross some terraces of the Duero River indicates the affected Duero River terraces are younger than those not formed from activity of the waters of this river. The "superficie de Alaejos" carve-out intrudes 4 to 6 meters into the Duero River terrace designated TD-7 (+74/80 m) to the northwest of Siete Iglesias de Trabancos village. Likewise, the TT-2 fluvial terrace of Trabancos cuts some Duero River terraces. Since the previously mentioned Duero River terrace named TD-7 has been dated by Alfredo Pérez-González (op.cit.) to the beginning of the Middle Pleistocene, meaning the river terraces of Trabancos River are younger than the "Superficie de Alaejos", it appears plausible that this postdates the creation of Trabancos valley: the proposed date could, thus, be halfway through the Middle Pleistocene or later.
History of the Trabancos region Although the eastern portion of the river is of insignificant hydrographic importance, at least until the 13th century, it played an important role in the history of the North Spanish Plateau.
Prehistoric era Evidence of prehistoric human habitation has been unearthed in hillsides in some areas of Narros del Castillo (Ávila), and in Siete Iglesias de Trabancos (Valladolid), dating from the Quaternary period, and have been further pinpointed as originating in the Lower Paleolithic era. At both sites, collections of lithic stone artifacts knapped during the Acheulean period are found on the surface (not as a result of archeological excavation), including centripetally knapped lithic cores, others displaying non-arranged lithic reduction, as well as lithic flakes characteristic of both the Levallois and Kombewa techniques, chopping tools, and handaxes.
Only ambiguous archaeological evidence has been found dating from the late Roman period. It has been suggested by some that this is a result of the severity of the land and weather in the Trabancos valley and its surrounding regions. Possibly, during the pre-Roman period the territory was a no-man's-land between the Hispanic tribes of the Vaccei and Vettoni.
Some archaeological remains have been found in the municipality of Siete iglesias de Trabancos (Valladolid), but they are not well preserved, having been situated on the surface of the terrain. Such remains consist of, for instance, broken pieces of comb-decorated pottery that appear to date from Spain's Iron Age. There are few other examples of prehistoric findings directly along the Trabancos river. However, in the surrounding regions, such as the municipality of Alaejos (Valladolid), archaeological investigation has unearthed several human burials sites that have been dated to the Bronze Age. In addition, some prehistoric remains have been found near the mouth of the Trabancos River, in Pollos village that originated from the Duero River. These include relics of the Spanish Bronze Age classified as Cogotas pottery, as well as Proto-Cogotas pottery, both featuring incised decoration.
Roman times The Romans likely came to the Trabancos region in the 2nd century, during the campaigns of Lucius Licinius Lucullus (152 BC), but the area was peripheral to the regions of principal occupation, as well as to the creation of early towns and more importantly, trade routes: most travel routes were in the east of this region, which followed the river Eresma from the town of Coca (Cauca, in Roman times) and Matapozuelos village (Nivaria in Roman times), up to Simancas (Septimanca); and at the west, for the "Vía de la Plata" ("silver road"), the most important Roman route in Lusitania Province. Nevertheless, it is known that in the Vallisoletan area, there were several villages that probably are of pre-Roman origin. In fact, the etymology of the word 'Trabancos' suggests a name originating before the Roman occupation.
At the Lavachicha site (municipality of Castrejón, Valladolid) several pieces of typical Roman pottery named terra sigillata hispanica have been unearthed and there was also an archaeological excavation in the 1980s that revealed a necropolis from late Roman times or, perhaps, from Visigothic times. Similar remains of late Roman pottery, have been found in Carpio (Valladolid), but only at ground level, and not from archaeological excavation. Another municipality crossed by the Trabancos River is Nava del Rey (a small town located in Valladolid), where, once again, are found superficial pieces of terra sigillata hispanica and a striking plate fragment with red gloss, resembling those that were carried by Roman legionaries on military campaigns.
The Middle Ages In the Middle Ages, the area remained a zone of little interest. No written documents exist prior to the 12th century that mention the region. It is known, however, that between 711 and 740 AD the Berbers had stationed troops in the valley of the Duero, but the majority of these peoples left the area because of a severe drought that occurred sometime between 750 and 753 AD. Only the most important centers of habitation survived (Medina del Campo, Olmedo, Alcazarén, Tordesillas, etc.).
During the Christian conquest, little emphasis was placed on resettling the region, as it was essential for the sovereigns of the time to consolidate more strategic zones (in the 11th century, priority was placed on the south of the Sistema Central, a mountain range located in the center of the Iberian Peninsula), which is why Medina del Campo remained intact into the 12th century.
Nevertheless, Tomas Mañanes, a professor at the University of Valladolid, who investigated the Trabancos valley and Guareña area, found numerous defensive turrets or "Torrejones" (according to the local dialect) that were dated to the 11th century; that is to say, previous to any official resettlement. Specifically, more than ten defensive structures of various sizes were verified along the course of the Trabancos River in the province of Valladolid.
Character and purpose of the Torrejones Almost all the torrejones are in areas now uninhabited (except those in Castrejón and Alaejos, both of which were turned into castles, in later history). The torrejones were relatively simple square or egg-shaped structures, with several floors, built of limestone or brick. At least two categories of torrejones can be identified: The first have small peepholes in their walls and are built in regions that were in isolated areas at the time of use, and the other are small castles located in what were rural farming villages (though today they are deserted).