Orientations of Preincaic Monuments

The Sites

Samaipata. Samaipata is a small village situated at 120 km to the south-west of Santa Cruz, on the road to Cochabamba. On the top of the hill named 'el fuerte', near the village, there is a very large sculptured rock, 200 meters long and 60 meters wide, orientated in the east-west direction.

In the sketch, according to Rivera Sundt (1979), 5 sectors can be noticed:
1) Sector 1: at the west end base of the monument there are a few circular pedestals curved with reliefs representing felines as jaguars and pumas. There are also eight curved pits aligned towards structures of the sector 2;
2) Sector 2: further east towards the top of the hill there are three rectangular sculptures about 30 meters long with 262 regular rombs curved in the rock. The sculpture represents a snake and is locally named 'El cascabel' ('the back of the snake'). This most interesting feature of the monument seems a trail pointing directly to the sky;
3) Sector 3: to the east of the monument a circular sculpture shows 18 seats named 'the Priest Choir' and many rectangular ditches;
4) Sector 4: to the north side of the hill top at the back of an enclosure there are five large trapezoidal niches above the niches there are grooves once possibly used to substain a roof;
5) Sector 5: to the south side of the hill top several niches terraces and other features are curved on he rock. Also the remains of the walls of several ruined ancient buildings possibly indicate the dwellings of the priests. 500 meters to the south-east there is a deep shaft ('chincana') of unknown purpose.

Probably this interesting monument was the centre of religious activities where fertility rites were celebrated. The carvings are dated with no doubt back to the Inca period by modern archaeologists. The makers are unknown. Archaeological excavations have shown a sequence of occupations: first a pre-tiahuanaco culture, then traces of this civilization that has connected this zone to the Andean region. Perhaps in this region, during the Inca period, have reigned the people of Chanè, ruling the lowlands under the Grigotà cacic. Later the Incas, allied with the Chanè, dominated this region untill the occupation by the Tupi Guaranì.

From the archaeoastronomical point of view, the most interesting feature is the orientation of the Cascabel, resembling to a trail taking to the the sky. This and two other directions have been measured, namely the direction of the 8 carved pits in sector 1 and the long rectilinear engraving in sector 1 near the seats complex. The orientation of the rock wall, in sector 5 facing south, has been measured too, it has five engraved pseudo doors. This wall has been worked to provide a better orientation for the walls extending towards the south from it. These structures are clearly Incaic. On a plane in front of them there are traces of walls made of 'adobes': probably these are the ruins of a house for the priests. The orientation of the axis of the house has been measured.

The Titicaca Lake. The Titicaca lake is the most sacred lake in the Andes. Near the lake there was the ceremonial centre of Tiahuanaco, the capital of the culture of the Aymara population, one of the most important in South America. It first developped around the time of Christ and lasted for over a 1000 years extending also into Peru and Northern Chile.

The Tiahuanaco region, together with the Collasuyu region, was conquered by the Inca army after defeating the Chanca, at the time of the emperor Pachacuti Yupanqui (ca. 1460AD). On the islands of Titicaca Lake the Incas have built important constructions like the one on the Island of the Sun, the Pilcokayna or 'Duke Palace', and the one on the Island of the Moon, the Acclahuasi or 'Virgin House'.

Pilcokayna - Island of the Sun (Titicaca Lake). The ruins are located half the way up the east coast of the Island of the Sun. The building is rectangular and contains rooms and several doors with the typical trapezoidal shape of the Inca style. On a terrace on the upper part of this construction a door offers a special view on the wide blue lake. The azimuths (A) and the height on the horizon (h) in the Pilcocayna monument have been measured in both directions, for each of the external walls. The front direction of the door opening on the upper terrace has been measured too.

Measurements and Interpretation

Samaipata. The orientation of the carved trail (measurement a) is the direction of the rise of the Pleiades at about 1AD. An observer at the top of the hill watching toward A = 71.0° and h = 0°, corresponding to the declination 18.1°, could see the rising of the Pleiades at around 500AD, and also the rising of Regulus in 600AD. The alignment of the 8 pits in sector 1 (measurement b) points to the rise of the Pleiades at 500BC and of Aldebaran at 500AD. The long rectilinear engraving in sector 1, near the seats complex, (measurement c) to the East matches the rise of the Pleiades at about 500BC.

If we consider that the Pleiades cluster ( 'Collca' in the quechua or 'Qutu' in the aymara languages) was important in the Andean world as a celestial signal for sowing (mainly mais) or for the prediction of yields, then it is possible to think that the alignments found at Samaipata were devised for the observation of this star cluster. Accordingly, the monument should have been built between 1AD and 500 or 600AD. Perhaps the eight pits were used first and the 'cascabel' later on, as a more recent construction. Of course only the archaeological research may work out a precise dating for the monument.

The orientations in (d) and (e) are both meridian, with a difference of 7.4° and 4.4°. They may have been chosen as a reference to the sun at noon.

	Structure	Azimuth	Height	Decl.	Object
a	Cascabel	71.0°	6.75°	+15.7°	rise of Pleiades 1AD and of Regulus 600AD
b	Eight pits	75.1°	6.0°	+12.2°	rise of Pleiades 500BC and of Aldebaran 500AD
c	Rect.engraving	74.9°	6.0°	-	rise of Pleiades 500BC
d	Rock wall	172.6°	-	-	Meridian
e	Axis of the house	175.6°	-	-	Meridian

The Ticaca Lake as seen from the Shuttle

Pilcokayna. The table shows the orientations measured in the island of the Sun. For the orientation in (c), we reckon an uncertainty of 1 or 2 degrees. This is the direction of the rise of the Pleiades at about XI century AD. Probably the alignments to the rise of the Pleiades are not casual, due to the importance of the star cluster in the Inca cosmology and also to the concurrence of their heliacal rise or set with many religious feasts.

	Structure	Azimuth	Height	Decl.	Object
a	Front wall opposite direction	155° 335°.4	0° 11°.3	-60°.5 +53°.4	rise of Alpha Crucis, Beta Crucis and Achernar 1500AD
b	south wall opposite direction	238°.9 67°.4	24°.5 -	-34°.5 +21°.8	set of Fomalhaut 1000AD, rise of Pleiades XIVcent.
c	frontal door of upper terrace	68°.9	-	+20°.4	rise of Pleiades XIcent.

Acclahuasi. The table shows the measured orientations in the island of the Moon. Of these c) and d), parallel to the shore, both point to the set of the Sun at the June solstice, which is the day of the Inti Rayni, the most important ritual festivity of the Incas.

	Structure	Azimuth	Height	Decl.	Objects
a	mountain wall opposite	116.4° 296.4°	10.0° 7.7°	-27.9° +22.8°	- June solstice Sun set
b	lake wall opposite	115.6° 296.9°	14.1° 7.8°	-28.0° +23.2°	- June solstice Sun set
c	SE wall	26.4°	-0.8°	+59.3°	-
d	NW wall	27.4°	9.1°	+16.7°	set of Pleiades at IIcent. AD

Conclusion

The number of matches suggests that these orientations, with great probability, were established intentionally. The Andean peoples kept up a wide interest at all times on the astronomical objects, especially the Pleiades and the Sun, both for their religious rites and their agricultural works.

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