UPPER COLCA PROJECT
Arequipa, Peru
Chivay / Cotallaulli Obsidian Source
Field Visit
Nicholas Tripcevich
October, 2001
Recently published descriptions of two principal obsidian sources in the south-central Andes prompted me to visit the the Cotallaulli/Chivay and the Alca source areas in September-October 2001 (Brooks, 1997; Burger 1998a; Burger et al, 1998b, 2000; Jennings and Glascock, 2002).
Reconnaissance Survey Notes
The following is based on field notes from a 3 day trip to the Chivay source. Please refer to maps and photos available on this website. The obsidian source was relocated based on coordinates and description given by Burger et al (1998a). Based on this information the west-facing slopes of Cerro Ancachita and Cerro Hornillo to the east of the town of Chivay were our initial objective. We climbed by way of the Quebrada de Los Molinos (panorama). Using published coordinates (Burger et al 1998b), we proceeded into the caldera on the north-western foot of Cerro Hornillo. Scattered obsidian nodules were observed in area (photo, GPS data).
The western shoulder of Cerro Hornillo was climbed first. Although some nodules were found eroding from the hillside no specific obsidian source area was noted. Interestingly, small walls and a possible developed spring water source were located in this area (photos, GPS). Additional walls and miniature structures were noted on the flat benchlands around 5000 masl immediately west of Cerro Hornillo (GPS). A panorama photo was shot from a promontory near there. From this area we surveyed northward towards Cerro Ancachita, a triangular peak of rhyolite, the highest peak in the vicinity. Cairns were noted leading out of the caldera to the east-south-east, the least precipitous route out of the caldera in any direction.
Obsidian was noted at the southern base of C. Ancachita prior to ascending the peak. The summit of Cerro Ancachita is made up of vesicular cobbles of aphanitic rhyolite. The summit (5,131 masl) provides a good view of the surrounding regions. The caldera was re-entered from the western shoulder of the peak. At the base of the peak an expansive zone of obsidian was found, several hundred meters further west of the less-dense distributions on the southern slope of the peak. In both areas the obsidian begins in the white ashy soil covered in grass and marshlands that appears around 4950 masl immediately downhill of the boulders that cover the flanks of C. Ancachita. Obsidian might further extend up underneath the boulders to higher altitudes but it would be inaccessible. The obsidian flows here are extensive, it’s safe to say that on the north side of the caldera below Ancachita half of the entire valley bottom is covered in obsidian. In this photo the whole expanse of obsidian deposits that we located are in view eroding out across the valley below the edge of the boulders field on the flank of Cerro Ancachita.
The best flow observed was in this area was just below the boulders on the east side of a bofedale immedately southwest of the summit of Ancacita (photo, GPS). Nodules in the area were noted that measured 22cm in length, 19cm diameter. No indisputably cultural lithic debris was noted in this immediate area.
Departing from the caldera to the south-westward an interesting corral covered in primary reduction obsidian flakes was noted (photos, GPS). See description of Corral 3 below.
Corrals and Cairns: Corral(s) 1
A number of corrals were also located in the valley, their age is difficult to determine. The first few to be located are very high (5000m) and are in a rocky areas far from pasture land near the top of Cerro Hornillo (photos 1-7). One walled area has rocks tiled inside the wall as if to level the sloping ground in the area and to cover the irregular surface of larger rocks in the ground in that spot. A double-alignment of rocks in the lowest part of a protected gully was found nearby. The construction is 2m by 3m, and is 90cm deep in the center. The location in the lowest part of the high valley suggests that it was a spring of water that has been developed (photos 1, 2), though currently there is no sign of moisture.
The other corral walls are on a rocky plateau partway up the south flank of the valley. It features a wall circling around the whole plateau area, a small rock shelter under one large boulder, some more complicated aligned walls that might have been a structure, and miniature doorways made of three rocks (photos 1, 2). Some obsidian flakes were found near the rockshelter, no ceramics or other cultural remains.
Cairns dot the landscape in various parts of the north-west flank of Cerro Hornillo. A trail suggested by series of cairns was noted climbing out from the center of the caldera at a bearing of 140 degrees. A large nodule with the cortex removed was seen along this series of cairns, high above where obsidian was occurring naturally.
Corral 2
This feature consists of a wall on one side and a number of large boulders and cairns on the other. It is underneath a red stain on the east wall of the caldera between Co. Ancachita and Co. Hornillo.
If it is the remains of an old corral, it is of interest because it is between the marked trail mentioned above and the abundant obsidian source below Ancachita. It is probably just a corral serving as a staging area for pastoralists and their herds making the push over the summit out of Quebrada de Los Molinos.
Corral 3
Because of the base of this corral was cleared of stones the natural obsidian is exposed. The base is littered with natural obsidian as well as some flaked material (photos). It is situated in one of the only sheltered location in the high valley, and it is immediately adjacent to the largest bofedale in the valley.
The structure consists of walls of flat stones and large boulders. There is no evidence of a roof, however some of the larger boulders serve as rockshelters and have fire scars on them. The corral is clearly maintain by modern pastoralists, some plastic soda bottles were noted. The entire floor of the corral was covered in dung, natural obsidian, and some primary reduction debitage.
Thanks to Wyatt Parzybok for his assistance in this visit.
References
Brooks, S. O.
1997 Source of volcanic glass for ancient Andean tools. Nature 376:449-450.Burger, R. L.
1998a The Alca Obsidian Source: The origin of raw material for Cuzco Type obsidian artifacts. Andean Past 5:185-202.Burger, R. L., F. Asaro, G. Salas and F. Stross
1998b The Chivay obsidian source and the geological origin of Titicaca Basin type obsidian artifacts. Andean Past 5:203-223.Burger, R. L., K. L. Mohr Chavez, S. Chavez
2000 Through the glass darkly: Prehispanic obsidian procurement and exchange in southern Peru and northern Bolivia. Journal of World Prehistory 14(3): 267-362.Jennings, J. and M. D. Glascock
2002 Description and method of exploitation of the Alca obsidian source, Peru. Latin American Antiquity 13(1): 107-118.