cross the territory from south to north, paralleling the Querétaro-San Luis Potosí highway. Most plains are located in the north, and are of sedimentary soil with some protrusions of volcanic rock. Altitude varies from 1,900 to 2,460 meters above sea level with the highest elevations at mountains called El Buey, Pie de Gallo, El Patol, El Nabo, and El Paisano. The city proper is on a plain at 1,900 meters. There is only one river, the Querétaro River, which carved the La Cañada. There are numerous streams, many of them seasonal, and fresh water springs near the mountain areas. The climate is temperate and semi-dry in which the summers can be hot, with high up to 36C in May and June. Freezing temperatures are possible in the winter. In most areas, various species of cacti can be seen such as the organ pipe and nopals, as well as the yucca. Trees adapted to dry climates include mesquite, willows and cypress, near streams and rivers. Animal life mostly consists of small mammals, deer, predatory birds and reptiles. In some areas, monarch butterflies can be seen as well. Nature reserves in the municipality include the Peña Colorado, Tángano, Parque Ecologicao Joya-La Barreta and the El Cimatario National Park. Near the city is the Sierra Gorda de Querétaro, part of the Sierra Madre Oriental, was declared by UNESCO as a Biosphere Reserve. This protected area is very rugged terrain, filled with canyons, steep mountains, waterfalls and deep abysses with a total expansion of 24,803 hectares. The area contains 360 species of birds, 130 species of mammals, 71 of reptiles and twenty-three of amphibians. It also contains about thirty percent of the country's butterfly species including the endangered Humboldt, the Jaguar the Oso Negro and the Guacamaya. Plant species include 1,710 different species including endangered species and is considered to be one of the best-preserved forested areas in Mexico. The Missionary Route of Friar Junípero Serra passes through here as caves such as the Sótano del Barro are located here. The territory contains deposits of gold, silver, manganese, tin, mercury, lead, zinc, opal, quartz, cantera stone (for building) among other minerals. UNESCO World Heritage Site In 1996, the historic center of Querétaro was declared a World Heritage Site by UNESCO. According to UNESCO's website, the "old colonial town of Querétaro is unusual in having retained the geometric street plan of the Spanish conquerors side