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.
Neffs Cave
In 1952 the Salt Lake Grotto of the National Speleological Society was established, and several weeks later the grotto's members obtained permission from the National Forest Service to explore the cave. They spent nearly eleven hours in the cave but had not reached the end of the main passage before they had to turn back. Teams from the grotto returned in 1953 and 1956, and in the last visit they succeeded in reaching the bottom of the main passage. They calculated a vertical depth of 1186 feet (361 meters), which was later revised to the present figure of 1163 feet (354 meters). Neffs Cave is the 13th deepest cave discovered in the United States.