Eddy (1977a, pp. 160-162) discusses a medicine wheel at Fort Smith, Montana, which has six spokes. One of these is aligned to the summer solstice sunrise, but the other spokes are not discussed.
Alice and Tom Kehoe (1979) describe effigy figures and medicine wheels that coincide with astronomical alignments. The most striking of these is the Minton Turtle effigy in south-central Saskatchewan (see Figure 6.40).
The principal alignment is from the tail to the head; it would have coincided with the heliacal rising of Sirius at summer solstice at ~2300 b.c. At 1 a.d., there would have been a shift of about 4° off this axis according to Eddy (cited in Kehoe and Kehoe 1979, p. 13). There is also a good summer solstice sunrise alignment and a possible sunset alignment for the same day. The height of the central mound would have prevented observation of the Sirius rising (at the horizon) with any precision unless there were a marker, perhaps a pole or a standing human. It is also possible that the central cairn was built later. But whereas at the 2300 b.c. date, Sirius's horizon rising could not have been observed along the axis if it was blocked by the central cairn (given the present height of the cairn), at about 1 a.d., Sirius would have appeared to rise over the center of the cairn (again at present height). The height of the central cairn also would have affected the visibility of the Sun at horizon rising, but a precessional shift would not have helped in this case. This monument has been identified as a representation of a badger by Brace (1987, pp. 92-93) on the basis of information from Cree and Assiniboine informants. This reflects the assumption that the uppermost features of the figure are "ears"; however, they also correspond strikingly with the eyes of a turtle viewed ventrally (see, for example, Figure 15.3).
At the Roy Rivers wheel, there seems to be a marker for summer solstice sunset. Although the Kehoes do not make such an argument, it could also be postulated that one of the 15 small cairns at the site marks summer solstice sunrise, which, however, still leaves 14 cairns unexplained. This brings us to the more general idea of the multiple purposes evidenced by the many different forms of medicine wheels.
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