# Schaefer 2020: A Case Study of the Picture Rocks Sun Dagger, Plus a Review of the Intentionality of Sun Daggers > Bradley E. Schaefer, James Stamm, 2020. 9 records on Mysteries Department cite it. The most recent re-analysis of the Sun Dagger's intentionality. Source: https://mysteriesdept.com/sources/SRC0D9KTCE25TNP/a-case-study-of-the-picture-rocks-sun-dagger-plus-a-review Publisher: Mysteries Department Licence: CC BY 4.0 (credit Mysteries Department and link the page) --- [Sources](https://mysteriesdept.com/sources)[Great houses of Chaco Canyon](https://mysteriesdept.com/mysteries/chaco-canyon)Schaefer 2020 **0** # A Case Study of the Picture Rocks Sun Dagger, Plus a Review of the Intentionality of Sun Daggers Bradley E. Schaefer, James Stamm, 2020. _Journal of Astronomical History and Heritage 23(3): 427-451_. A field study of a Hohokam sun dagger near Tucson and a review of sun daggers in the Southwest. Using two regional surveys whose declinations cluster at the solstices and equinoxes, it argues most such markers are intentional, but that chance light-and-shadow coincidences on spirals run at 20 to 33 per cent, that one spiral marking three or four dates is very unlikely, and that at Fajada Butte at most two of the four claimed markings are intentional and the lunar ones are chance. It reads sun daggers as sun shrines, not calendars. **Great houses of Chaco Canyon** Articledoi: **[10.3724/sp.j.1440-2807.2020.03.01](https://doi.org/10.3724/sp.j.1440-2807.2020.03.01)** Checked against the original0 ## What it's used for here The most recent re-analysis of the Sun Dagger's intentionality. ## Cited by on this site 9 records [The light play on the spirals is coincidence; the spirals were not placed to mark the sun.](https://mysteriesdept.com/mysteries/chaco-canyon/answers/ANS0D9KVKQW67D9/the-light-play-on-the-spirals-is-coincidence-the-spirals) Answer ANS [A 2020 review treats the slabs and their edges as natural.](https://mysteriesdept.com/mysteries/chaco-canyon/evidence/EVD0D9KVJGT44D0/a-2020-review-treats-the-slabs-and-their-edges-as-natural) Evidence EVD [Across the Southwest, light-marking sites cluster at the solstices and equinoxes far above the chance…](https://mysteriesdept.com/mysteries/chaco-canyon/evidence/EVD0D9KVH9R2VGB/across-the-southwest-light-marking-sites-cluster-at-the) Evidence EVD [Chance coincidences of light and spiral are common, 20 to 33 per cent of candidate sites in one field test.](https://mysteriesdept.com/mysteries/chaco-canyon/evidence/EVD0D9KVKZP1TBZ/chance-coincidences-of-light-and-spiral-are-common-20-to-33) Evidence EVD [Ethnography of the descendant peoples links sun daggers with sun shrines, where a sun-watcher kept vigil with…](https://mysteriesdept.com/mysteries/chaco-canyon/evidence/EVD0D9KVKG244EY/ethnography-of-the-descendant-peoples-links-sun-daggers-with) Evidence EVD [One spiral designed to mark three or four separate dates is very unlikely; the extra dates are most likely…](https://mysteriesdept.com/mysteries/chaco-canyon/evidence/EVD0D9KVNY65NF6/one-spiral-designed-to-mark-three-or-four-separate-dates-is) Evidence EVD [The probability that a single spiral was designed to mark four dates is very small.](https://mysteriesdept.com/mysteries/chaco-canyon/evidence/EVD0D9KVPNM46QK/the-probability-that-a-single-spiral-was-designed-to-mark) Evidence EVD [Two regional surveys find the declinations of light-marking sites clustered at the solstices and equinoxes,…](https://mysteriesdept.com/mysteries/chaco-canyon/evidence/EVD0D9KVM7G4W53/two-regional-surveys-find-the-declinations-of-light-marking) Evidence EVD [The great houses of Chaco Canyon](https://mysteriesdept.com/mysteries/chaco-canyon) The mystery article MYS ## Cite it ``` Schaefer, B. E., & Stamm, J. (2020). A Case Study of the Picture Rocks Sun Dagger, Plus a Review of the Intentionality of Sun Daggers. Journal of Astronomical History and Heritage 23(3): 427-451. https://doi.org/10.3724/sp.j.1440-2807.2020.03.01 ``` [Read it free at doi.org](https://doi.org/10.3724/sp.j.1440-2807.2020.03.01) Key **SRC** 0D9KTCE25TNP Kind Journal article Rights arXiv-nonexclusive Kept 27 Oct 2026, for editors Checked Against the published article Added by [apollo](https://mysteriesdept.com/u/apollo) The record Bibliographic records are CC0. Take this one as CSL-JSON, BibTeX or RIS. [CSL-JSON](https://mysteriesdept.com/sources/SRC0D9KTCE25TNP/a-case-study-of-the-picture-rocks-sun-dagger-plus-a-review/csl.json)