Tlacolula de Matamoros
The caves and rock shelters vary in size and what they contain. Many contain paintings and other forms of graphic representation. Contents include ceramics and stone tools. The corn materials show similarities to the first vestiges of the domestication of wheat and rye in the Middle East. One of the deepest caves is called the Cueva de la Paloma. The caves have been studied since the 1960s, especially the Cueva de Guilá Naquitz (white stone in Zapotec), which has some of the best evidence for the domestication of corn and squash, which dates back more than 10,000 years. Other caves, such as those near Yagual and Mitla confirm findings at Guilá Naquitz and show human occupation to about 8000 years BCE the sites also show similarities to the Head Smashed and Buffalo Jump Complex sites in Canada. Many more smaller caves with similar artifacts are thought to exist in the area.
Canyon
The Yarlung Tsangpo Grand Canyon (or Tsangpo Canyon), along the Yarlung Tsangpo River in Tibet, is regarded by some as the deepest canyon in the world at 5,500 m (18,000 ft). It is slightly longer than the Grand Canyon in the United States. Others consider the Kali Gandaki Gorge in midwest Nepal to be the deepest canyon, with a 6400 m (21,000 ft) difference between the level of the river and the peaks surrounding it.