after the volcanic rock it is principally made up of. Other elevations include Cerro Viejo, Napateco and Las Navajas. The main river is the Tulancingo River, which is part of the Metztitlán River system. There are four small lakes called Los Alamos, Otontepec, San Alejo and La Ciénega. The climate is temperate to cold with an annual average temperature of 14C and average rainfall of between 500 and 550 mm per year. Most rain falls from June to October. Forested areas include trees such as pine, ocotea, oyamel, cedar and walnut trees. Most wildlife consist of small mammals such as rabbits and squirrels with birds such as hummingbirds, doves and woodpeckers and reptiles such as snakes. In the Tulancingo Valley, some of the oldest human remains of Mexico were found in Tecolote Cave. However, the most important site is Huapalcalco. This site is located about three km from the center of modern Tulancingo and contains a pre-Hispanic pyramid and cave paintings. In the cliffs of Huapalcalco and nearby, there are fifty groups of cave paintings, some of which date back as far as 10,000 BCE. The pre-Hispanic site was first excavated in the 1950s by Instituto Nacional de Antropologia e Historia (INAH). Carbon dating has placed objects as far back as 1,100 BCE. In the 7th century, a ruler by the name of Quetzalcoatl ruled here until he left to found Teotihuacan. While the remains of this site do not look impressive, they are the forerunners of the Teotihuacan civilization. The center of the site is a five-level pyramid measuring twelve meters at its base and is eight meters high. The function of this site was that of a ceremonial center. At the top of the pyramid, there is a monolithic altar, which was probably used for the deposit of offerings. The name means House of Green Wood. Most people of the city are familiar with the San Miguel Municipal Cemetery located on Miguel Hidalgo Street in the main city. However, the city and municipally have a number of notable cemeteries. Cemeteries here are a custom brought and imposed by the Spanish after the Conquest. Prior to this, the indigenous peoples buried their dead underneath their houses. The first cemetery in the city was located next to what is now the cathedral. Today, this cemetery no longer exists, as it has been abandoned and built over. Another notable cemetery in