||The River Nedonas travels through the town of Kalamata. Its mouth lies west of the Kalamata harbour and its catchment area lies at the western side of the north part of Mt. Taygetos. The special feature of this site is a deep narrow gorge, with a length of 9 km, lying between Chani Lagou and the military shooting area just north of Kalamata. This gorge has a SW-NE axis vertically crossing the axes of the mountains the main peaks of which are: Klera (689 m), Goupata (867 m), Amoutsa Korfadi (970 m), Melisto (1237 m), all to the northwest of the gorge, and Koryfi (480 m), Aetos (944 m), Agios Georgios (1104 m), all to the southeast of the gorge. The Kalamata-Sparti national road follows the line of the gorge, which is the only natural pass between the two towns. The typical landscape of this site is formed by deeply carved limestone occurring along the gorge as well as the tributaries, the main ones being: Karveliotiko Rema (just east of km-stone 13), Grias Rema (just to the northwest), Dafnorema (north of Angoudi Rachi) and Skoura Rema (between Goupata and Klera). These black bituminous limestone belong to the Tripolis geotectonic zone and are deeply karstified. Stratigraphically, they are overlain by the Oligocene flysch formation (siltstones, claystones). The substrate of the limestones is phyllitic-quartzitic rock (metamorphic units of the Tripolis zone). These metamorphic rocks outcrop in the Cheromata-Lazarolakka and Alagonia-Artemisia areas, east and north-east of the site. Their relative impermeability ensures a high runoff of water moving towards the Nedonas gorge. Due to the karstification a high percentage of runoff water in the Nedonas riverbed infiltrates through the limestone, thus contributing to the enrichment of the groundwater and maintaining the relatively low runoff towards the river mouth. The geomorphological development of the Nedonas gorge is due to extensive erosion which occurred during the postalpine elevation of the area; erosion was promoted across large NE-SW striking faults. At the same time, zones of weakness in the limestones (due to tectonic stresses) were exposed to erosion, thus promoting rockslides and landslides on the slopes. This led to the temporary obstruction of the water flow in the gorge and to the formation of small lakes behind dams of landslide material. These longitudinal lakes were not perennial; the destruction of the dam during a subsequent flashflood was the rule, but muddy sediments were left behind and formed a locally soft substrate for plants. A striking example of such a process can be observed at the km-stone 16. Extensive rockslides on steep slopes occurred during the Kalamata earthquake of 13.09.1986, which led to a temporary closure of the Kalamata-Sparti national road. With the exception of the tectonically strongly affected zones of steep slopes, the limestones offer stable substrate for plants and trees to establish biotopes. Karstic holes and caves have been observed in many places along the gorge. These indicate older levels of groundwater circulation as well as positions of paleo-springs, before the deepening of the gorge to its present level. These holes are very important habitats for many wild animals (bats, foxes, hares, birds etc.) according to the location, the relative accessibility of water, and the degree of safety which they offer to the respective animals. The maquis vegetation belonging to the Oleo-Ceratonion zone is highly developed and of very good quality and biodiversity. This is due to the following factors:- The orientation of the Nedonas gorge ensures low insolation at least for the northwest exposed sides, thus preventing an environment too dry for plants growth. This has a positive effect on the biomass production of the maquis, which thrives under favourable conditions.- As a result of the above factor, fires which could otherwise destroy extended areas of woodland in the open mountainous area, even at higher altitudes, are less effective in the relatively humid microclimate of the gorge. So, the survival of an ecosystem established in the gorge is more probable. This also seems to be a positive factor for the animals which may remain undisturbed in the gorge without the danger of fire.- As the gorge connects the lowland of the Kalamata area with the highland of Mt. Taygetos, this ensures a high probability of species mobility (especially of animals searching for food, water, security and a new territory). Plant seeds can also be easily transported through the gorge by means of animals or floods. - Since the largest part of the gorge itself is not easily accessible to man, due to steep topography and low agricultural value, a further advantage is therefore offered to the flora and fauna of the gorge. The only accessible area of the gorge is near to the km-stone 16, where olive trees have been planted and the shepherds bring their animals (goats and sheep) for watering. The rough geomorphology of the area, does not permit the establishment of villages. All residences are distributed in places outside the Nedon as gorge. Scattered smaller agricultural and pastural buildings and homes, are met mainly on the southern flank of the gorge, on the small plateaus above it. The ecosystem seems to be in an equilibrium with grazing animals. This is due to the density of natural maquis vegetation, the inaccessibility of most localities, and high biomass production as described above. As far as the Nedonas Plain and the southwestern end of the gorge are concerned, the natural ecosystem is almost totally absent due to urbanization in the town of Kalamata. The straightening and the concrete cover of the riverbed and riversides, has destroyed all natural vegetation, which has been replaced with artificially planted and irrigated trees. Ironically these trees are irrigated with water pumped from boreholes just next to the riversides. There is also a limestone quarry at the southwestern end of the gorge, just beyond the military shooting site. However, these factors do not minimize the great aesthetic value and scientific importance of the Nedonas gorge.