The Guara Western Mountain-Chain, is corresponded with the vastest part of the Externals Hills of Pyrenees, next to the Somontano (Under-Mountaines) of Huesca and it is an anticlinal that is directed the Depression of the Ebro River. It is shown as a bulk of calcareous and sandstones of the cretaceous and the eocene crossed, and even cut, by the Alcanadre, Guatizalema, Isuela and Flumen rivers, what gives cause for "foces" (river throat) of huge beauty, very appreciated by the alpestrian.

Emphasizes in the vault anticlinal, the peak of Guara, with its 2.077 m. of height. The erosion has given cause for you scarp known in the Pre-Pyrenee with the name of "Mallos"; and in this zone there are in Gratal, Roldán, Vadiello, Riglos, Agüero, etc.,.. The presence of glacis (levelled, declivitys) permitted the useful bench-covers existence for the cultivation (Used, Nocito, etc., ..) that today, as a rule, they are abandoned. The eocenes marls (of gray bluish, and abundant in the Canales -Berdún for example-) form wide depressions in the confluences of the rivers and ravines, what facilitated the creation of dammings, as that of Belsué of 14 Hm3. (near it is the Refuge of Guara), that of Vadiello for the waters of the Guatizalema (16 Hm3. for 69 Ha. dammed), that it is a spot very it frequented by burglars and apprentices (there they are the famous pegs); and the most ancient, that of Arguis,for the waters of the Isuela river.

The project of this last damming (Arguis), date of the XVII century being his accomplisher, Mr. Francisco de Artiga. It was made an increase in 1.929 (2,7 Hm3.) that permitted to water in the Hoya (hollow) of Huesca 2.500 Ha.(*). It is located the damming, in the depression understood between the Mountain Chain of the Eagle and Gratal one (peak of San Julián ·1.529 m.·), with the population of Arguis in its margins, to 1.044 m. of altitude, in the ancient highway that was carrying to the port of Monrepós (22 Km. to Huesca). Is a tourism enclave to Sundays walker, that takes advantage the water, to the shade and the bars and food services.

In Geology, the Mountain Chain of Guara understands all the territory band, more or less folded, that to I peep of the Pyrenee form part of the External Mountain-Chain of it , of West to East of the System, and whose origins are soared to a sedimentary grave during the secondary Era to the Terciary, with accrued calcareous elements that, to be lifted slowly (around the end of Eocene), form the own relief that characterize it. Below, the erosion demolished part of these materials and buried them, fossilizing with pudingas (rounded stones conglomerated) and conglomerate the pre-existents relief. New subsequent erosion, isolated the hardest sediments, emphasizing material in the landscape (above all conglomerates), letting erect steep and mallos. The primitive water courses reflect in increase and begin to be encased little by little, building narrow steps, that in million of years form the current throats, waterfalls, gorgas, gorges and trenchs in hard soils, that it is where reflect the waters. A previous observation to the composition or lythological structure of the Mountain Chain of Guara, will permit us to understand the abundance of karstics phenomena, that in this zone are not so abundant as in the Easterner (there be at the point 11 Kms. of tour, in the Solencio de Bastarás). Of the almost 80 Km2. of karstics lands of the Mountain Chain of Guara, nine are occupied by conglomerates, of mainly calcareous nature.

Historically, as nearly all the explorations of the Pyrenee of Huesca, have origin in the spontaneous initiative of French naturalists and some national: Lucien Briet or Lucas Mallada for example. It is 1.966 when an accident in the Grallera Alta, conditions that the Speleologic Group of Badalona makes the first decrease to that cavity and since then is begun a series of projects in that zone. Intervened as support group, members of Peña Guara" (Society from the mountains), that from that collaboration formed the group of Spelelogy that, with the time, it has channeled the principal activity in this Western sector of the Guara Mountain Chain.

In Climatology, this zone is of transition between the cold of the mountain of Pyrenee and the continental climate of the Depression of the Ebro river. In the Half North (Gratal and Guara), it does not make excessive heat in the Summer, being the inferior rains to the of the Pyrenee but superior to those of the Depression of the Ebro. The era of more rains is the Autumn by a greater Mediterranean influence. The minima are given in Winter and Summer though in June and September also it can rain what is its. What is customary is that are registered between 700 mm. and 800 mm., but in all the zone are surpassed 500 mm. (Huesca: 551 mm.) with respect to the temperatures, the annual average is in connection with 12 degrees. In Winter 7,5º and in Summer 18º. Minimal absolute of - 14º (Belsué) in the month of February. Sporadic frosts in May. For the Hoya de Huesca, these values means are located in 23º in Summer and 4,6º in Winter. In Summer can be reached 40 degrees and they are frequent 35º; while in Winter, the temperature does not rise of 10º, and stays in 0º during days. Spare the days of violent Cierzo (North wind) and the fogs (that yes are frequent in Arguis). This impinges on the vegetation favoring the presence of the carrascal (ground covered with small holms oaks) of sweet acorn with a forest of junipers, mastic tree, bearberry and arbutus. Frequently, the carrascal is demoted and given step to the aromatic plant scrub (rosemary, thyme, lavender) or the appearance of variants (aliagas -ligneous shrub-). Most dry and sunny soil is shared by the carrasca-pine; the young-oak forest appears in the sunlights; there is abundance of grasss of crunches alpine, much more fresh in the expensive North (greater snow) while in the sunlights, the grass is finer but buds very soon. The box, in the abandoned grass zones, finishes being imposed, conditioned the possible entry of the cattle that is stopped before the scrub. Exist good forest repopulation to laricio-pine base, with mountain annotations by periods of fifteen to twenty years that it has resulted in detriment of the cattle-raising. To practical effects, nearly all the North half is abandoned to the forest development.

In Demography, the population experienced a decrease accused from 1.960 with an emigration of the field to the city, that drove to the entities disappearance of population as Bentué de Nocito, Ibirque, Used, etc., ... that they are scarce example. If to the industrial development was joined to it some demoted grasss and scarce agricultural resources, it can be understood the massive emigration that was channeled to Huesca and in smaller proportion, to Sabiñánigo. Thus since, data of the census in 1.980, gave in the municipalities of the zone a population of 1.365 inhabitants, aged, with an ages pyramid in exempt regression; there were entities that they were not registering neither births nor marriages in many years.

Economically it corresponds to this zone a mixed economy of mean mountain: the traditional cattleman - forest (ruined by the emigration), and the grain producer. There are large difficulties for the development agricultural: pending notables, shortage of depressions and of cultivable terrace; near a continental climate very accused, is joined the absenteeism of the owners that finishes in a sub-development of the earthly devoted finally, in part, to the cereal. The properties are generally large by the emigration and the sale of the goods. It exists a Neighbors Society, named "of the Honor", in Nocito that acquired 800 Ha. of grasss in the Mountain-Chain of Guara with capacity for 5.000 wooly, as well as the pardinas(labour grounds) of Zamora, Sierrahum and Usieto.

These calls pardinas, they are a form of development originating from abandoned peoples, properties of the church or defensive zones that they were bought by particular, groups of cattlemen or for the ancient Forest Patrimony of the State, to widen its development. Tend be large (more than 200 Ha..) in lands little able for the cultivation but with a multiple utilization (agricultural, cattleman and forest).

The small terraces and depressions are employed for the cereal and the orchard (10 Ha. maximum). The inhabitable kernel tends be a great building (or more than one) complemented additionally scattered by the mountain; generally there is corral. Was tending be attended by medieros (men who work for a half benefice) who were obtaining a tenth or fifth part from the crop and the whole the cattle activity, without benefit on the forest development. Those of the Mountain Chain of Guara was rented for grasss to the Roncal, Ansó and Hecho (moving from winter to summer pasture or vice-versa). Also they were employed as "aborrales" where the cattle was happening 15 days in its road to the bank. Today they are intended for the cattle-raising. The cultivated agricultural surface is minimal and discontinue. What more yield gives, they are: the potato, forage and orchards (the almond-tree in the southern municipalities). The wooly cattle is in decadence: something of bovine in Arguis and Nueno; and the goat cattle takes advantage the scrub of the sunlights of Guara. All this completes economic table of a region whose only inducement is the tourism of the day or of the week-end, that uses the refuges, descends by the rapids of the rivers or envisages the beautiful landscapes; natural beauties of Vadiello or Guara, the Hermitage of San Cosme y San Damián, etc., .... From 27 of December of 1.990, this geographical area, was designated PARK OF THE MOUNTAIN-CHAIN AND THE CANNONS OF GUARA