Geography-Physical Characteristics

Geology, Geomorphology and Soils.

GEOLOGY, GEOMORPHOLOGY AND SOILS

From a geological point of view, the proposed territory belongs to the Hercynian domain, covering the entire western region of the Iberian Peninsula. The predominance of siliceous materials as well as the revival of the ancient systems of faults and fractures caused by Hercynian origin of the Pyrenean mountains have determined a very irregular relief in this region, characterized by a complex series of mountain ranges, deep valleys and small tectonic depressions. In this landscape granite masses, in soft and round stand out, along with other steep blocks, more common in the mountains which form the eastern boundary of the proposed area, where slate-quartz screes and ridges abound. Among them we can find bands of limestone materials with low power, corresponding to the Vegadeo, Cándana and Aquiana formations.

The core of the proposed space is represented by the Terra Chá, the largest sedimentary basin in this sector, where Neogene materials have accumulated: marl and other detrital fine sediments from the upper Miocene, on which the depositional and most recent edaphic cycles have later developed. This great depression, which represents a large flattening area, more or less degraded by the action of the Miño river basin, is framed by the Northern Ranges (Xistral, Carba, Lourenzá and Cordal de Neda) by the Galician Ridge (Ranges of A Loba and Cordal da Serpe) to the west and the ranges of Meira, Mirador and Puñago to the east. The flatland extends until it reaches Lugo, only interrupted by small residual elevations or “outeiros” (small elevations of land isolated and of little extension).

From the edaphic point of view, the fundamental catena which could be established from the peaks to the lower areas, would comprise a soil sequence that starts with Leptosols (Litosol and Ranker), continuing on Cambisoles of Dystric, Humic or gleico types, according to drainage conditions. In almost permanent hydromorphic environments and massive texture, Gleysols are formed, especially in areas with marl, while from unconsolidated rocks and poor bases, Podzols can be formed. Alongside these soils, Histosols (peat bogs) stand out, located in low-lying areas associated with flooding conditions, as well as in slopes and peneplains in mountain areas, where the cold and heavy rainfall play a key role as a limiting factor on the decomposition of organic remains. Finally, we would find Vertisols, associated with flat topography, which present a high clay content, and impose severe limitations to vegetable growth.