The daily recording of sunsets from the dotted crosses of Acalpixca and Atlapulco in Xochimilco, Mexico City

Abstract

Here we present an analysis of the Pecked Crosses from a perspective based on naked-eye observation of solar sunsets, from the center of the cruciform designs, and the descent of the Sun on prominent hills, already detected in other studies of the Cuenca de Mexico, which were occupied to record calendar dates, such as the Preclassic site of Cuicuilco and the Postclassic site of Tenochtitlan. To the west of Mexico City, the San Miguel Hill and the Ajusco volcano, belonging to the mountain range of Cruces, were important promontories that were part of the indigenous worldview, with relevance comparable to the volcanoes of the east, such as Popocatépetl and Iztaccíhuatl. On them important rites of request for rain and fertility were carried out and to date are the scenes of these Catholic syncretic practices of the wooden crosses visited on the day of the Holy Cross and other dates by the residents of the nearby settlements.

The study began by counting the holes in the pecked crosses to see if they have a calendrical value. Located in the crosses and pyramids, the sunsets were observed, recording the dates on which the Sun descended at relevant points. The azimuths of the Sun were also measured. their axes with a compass and the height of their horizons towards which their lines are directed with a clisimeter. In the case of pyramidal structures, the theodolite was used to measure their orientations, obtaining interesting results.

What we found is that in one of the ACA 2 crosses the points contained in its design add up to 253, a number very close to the ritual calendar count of 260 days, and that the axes of the crosses mark twice the date of the zenithal transit, dates of the Cuicuilco horizon and the alignment at sunset of the Templo Mayor of Tenochtitlán. We detected a very relevant sequence of days that makes us think that the positions of the Sun seen from the pecked crosses were used to locate the points of the territory where the pyramids were to be built, based on the sunsets of certain days, according to a daily sequence previously observed. Reusing as observation points the Pecked Crosses located in the mountainous area of Acalpixca and Atlapulco, to orient the pyramidal structures in the Postclassic sites (Barrio del Huacal and Barrio de Tenezcalco). This proposal is different from that of Aveni, who measures the orientation of the axes of the crosses and sees that the azimuths of the petroglyph coincide with the degrees of deviation of the urban layout of Teotihuacan and thinks that the cruciform designs were used to orient the city.