This mountainous region is one of the chains that form the Transversal Neovolcanic Axis which goes from the Pacific Ocean to the Atlantic with a width that varies between 20 and 75 kms. Small earthquakes in the southern part of Mexico City, originate under this range and statistics exist which foretell the birth of a new volcano in the following 1,000 years. The Chichinautzin has 76 major craters without including its offsprings. One of the most important is the Cuautzín measuring 3,510 mts above sea level, the Toxtepec surrounded by a broad lava field and the Pelado with a base of ample forest (3,620 mts. above sea level). Located between the City of Mexico and the City of Cuernavaca, this zone is an important lung provided by nature.