sentences:  The archaeologist Eliécer Silva Celis pioneered in the study of them in the 1960s.Later research has been performed by Carl Henrik Langebaek, Diego Martínez, Álvaro Botiva, Pedro Argüello García, and others.The black, red and white rock art is present at an altitude of at and shows human faces, Suns, maize, eyes, mountains, masks, and other figures.