the limestone plateaus of Borja and of Zaragoza. Sistema Ibérico The Aragonese section of the Sistema Ibérico straddles the provinces of Zaragoza and Teruel. It is a set of hills without a clear structural unit, which can be divided into two zones: Sistema Ibérico del Jalón and Sistema Ibérico turolense. In the first, the Moncayo stands out with , formed by Paleozoic quartzites and slates, partly covered by Mesozoic limestones. The second is formed by elevated terrain (from to in general), but flattened and massive. To the southwest of the depression the summits of the Sierra de Albarracín range are reached above , southeast the are reached in the Sierra de Javalambre range and finally the Sierra de Gúdar range () transitions to the Maestrazgo area in the Valencian Community. Climate and vegetation There are two main types of climate in Aragón, the Semi-arid climate and the Oceanic climate. Its irregular orography creates several microclimates throughout the entire community. From the High mountain Alpine climate of the central Pyrenees to the north, with perpetual ice (glaciers), to the Humid subtropical climate (which is very common in Huesca's lower altitude areas) to the steppe or semi-desert zones, such as the Monegros Desert, passing through the intense continental climate of the Teruel-Daroca area and the Mediterranean climate in the southern areas bordering Castilla La Mancha and the Valencian Community. The main characteristics of the Aragonese climate are: Rainfall is mostly low, with much of Aragon placed in a bowl of low ground between the Pyrenean mountain range to the north and the Sistema Ibérico mountain range to the south, cut off from maritime air masses. This situation means that the rain falls mainly in the higher areas, and that the temperature range features large contrasts, with cold winters and hot summers, as typical of continental climates. Rainfall is also irregular, as typical of Mediterranean climates, with randomly alternating dry and wet years. The air currents are often encased in the middle Ebro Valley from northwest to southeast, giving a characteristic wind, the cierzo, which stands out for its intensity and frequency. Temperatures are very dependent on the altitude. In the Ebro Valley the winters are relatively moderate, although the frosts are very common and the thermal sensation can decrease a lot with the cierzo. Temperatures in summer can exceed 40 °C in the central areas. In mountain areas winters are long and