(Pre-Columbian) Amazonian rock art

Amazonian rock 'art', in the form of petroglpyphs, are concentrated in the mountainous parts of its northern range, from Columbia to the Guyana's and Venezuela. Their function remains obscure and there does not seem to exist a systematic overview. One of the most impressive sites is Werehpai in South West Surinam. The site was discovered and named by a Trio named Kamanja was also part of the excavation crew. The site holds 313 petroglyphs. The fact that in all of Surinam there are 192 other petroglyphs known, distributed across 29 sites, gives a clue about Werehpai's magnificence. Charcoal and pottery found at the site have been carbon-dated as 4200 to 5000 years old.

The most famous site is the Venezuelan Caverna da Petra Pintada, the 2nd image shows a marvellous matrix-like structure on the right. The last 2 are from Venezuela but from other parts of the country. This is a great website with many pics in a for me unreadable language.

Taken from Hanlon's 'in trouble again'.

Brancusian if anything.

The oldest reference that I am aware of is "Notes of a botanist on the Amazon & Andes 
being records of travel on the Amazon and its tributaries, the Trombetas, Rio Negro, Uaupés, Casiquiari, Pacimoni, Huallaga and Pastasa : as also to the cataracts of the Orinoco, along the eastern side of the Andes of Peru and Ecuador, and the shores of the Pacific, during the years 1849-1864" by botanist Richard Spruce whose observations (and illustrations) are perfectly clear:

Although we have no elements where from to determine positively the date and mode of execution of the picture-writings, those questions seem to me to have been involved in unnecessary mystery. The instruments used in scraping such deep lines in the granite were probably chips of quartz crystal, which were the hardest cutting-instruments possessed by the aborigines of South America. In the Amazonian plain I know of but two extensive deposits of large rock-crystals one of which is a good way up the Rio Branco, and the other is at the foot of Mount Duida, near the village of Esmeralda, therefore in the immediate neighbourhood of the Casiquiari. I know also of but one such deposit on the Pacific side of the Andes, namely, in the hills of Chongon near Guayaquil; yet pieces of quartz, some of which have served as knives, others as lance- or arrow-heads, are found strewed about the sites of ancient towns and settlements through several degrees of latitude. Whatever the instrument used by the Indians of the Casiquiari, it is difficult to assign any limit to the time required for the execution of the figures; but any one who has seen an Indian patiently scraping away for months at a bow or a lance before bringing it to the desired symmetry and perfection, or who knows that it has taken a lifetime to fashion and bore the white stone which the Uaupes Indian wears suspended from his neck, will understand that time is no object to an Indian. I can fancy I see the young men and women sitting in the cool of the morning and evening, but especially in the moonlight nights, and amusing themselves by scratching on the rock any figure suggested by the caprice of the moment. A figure once sketched, any one, even a child, might aid in deepening the outlines. Indeed, the designs are often much in the style of certainly not at all superior to those which a child of five years old in a village school in England will draw for you on its slate; and the modern inhabitants of the Casiquiari, Guainia, etc., paint the walls of their houses with various coloured earths in far more artistic designs. 

Having carefully examined a good deal of the so-called picture-writing, I am bound to come to the conclusion that it was executed^by the ancestors of Indians who at this day inhabit the region where it is found ; that their utensils, mode of life, etc., were similar to those still in use ; and that their degree of civilisation was certainly not greater probably less than that of their existing descendants. The execution of the figures may have ranged through several centuries, a period which in the existence of a savage people is but a year in that of the highly-civilised nations of modern Europe. In vain shall we seek any chronological information from the Indian, who never knows his own age, rarely that of his youngest child, and who refers all that happened before his own birth to a vague antiquity, wherein there are no dates and rarely any epochs to mark the sequence of events.