Abri Blanchard Calendar: The Moon

Possible Origin of the Yīn Symbol

Images: Lynn Fawcett
Images: Lynn Fawcett

The two dots or lines of the yīn symbol are associated with the moon, darkness, and night. The reason for the choice of notation can perhaps be understood if we look at the diagram on the left above. It is based on a beautiful time-lapse photograph by Juan Carlos Casado. Mr Casado took pictures of the sunset followed by the moonset at the Spring Equinox in 2008. Hence we have the possible inspiration for the yīn symbol, sunset on the right and moonset on the left. From this I concluded that the Abri Blanchard bone depicts cycles of both the sun and the moon.

Using the data for Bordeaux in February and March 2013¹, I have added the dates and phases of the moon to Mr Marshack’s diagram. I have no idea if this is a valid thing to do. It may be pure coincidence, but the moon's phases appear to match those on the bone.

Image: Alexander Marshack © Peabody Museum: Annotation: Lynn Fawcett
Image: Alexander Marshack © Peabody Museum: Annotation: Lynn Fawcett

The diagram (above) begins with the Chinese New Year on 3 February (the solar term lìchūn). It is a cross quarter day; the equivalent of the European festival of Imbolc. At this point the solar longitude is 315°. Note how Mr Marshack’s analysis gives us a unique version of the yīn symbol. The starting point is clearly marked.

Next note how we have two marks for each day with the exception of 12 February, when the new moon first becomes visible to the naked eye. Likewise, there is an extra mark on February 24 when the moon does not pass the meridian, and therefore does not rise or set on that day.

Then note how the cycle ends on 4 March below the point at which February 3 begins the cycle. If you follow the spiral round, you can see that it resembles what we currently think of as the infinity symbol. The never ending cycle of time that governs all of the 'clocks' on Earth. In astronomy this shape is known as an analemma.

Abri Blanchard: Sunset and Moonset



Sunset Time

Sunset Azimuth

Moonset Time

Moonset Azimuth

2 February 2013





3 February 2013





4 February 2013





Data prepared with Solar Calculator 2.2 from iesmith.net2, using the decimal coordinates: Latitude: 44.999556° and Longitude: 1.101306°. Time is local time (CET). The magnetic declination adjustment was disabled.


Lastly, let’s take another look at the data for 3 February 2013. I chose 2013 as the source for the illustrative data simply because it is the current year (I am writing this in July 2013). If you look at the data in the table, you will see that the azimuth for the sunset on 2 February and the azimuth for the moonset on 3 February are less than one degree apart. In other words, the sunset and the moonset were aligned like the yīn symbol. I don’t know how often this alignment would occur on 3 February, but it is certainly not every year.

Coincidentally, 2013 represents the beginning of a new cycle known as a bak’tun in the Mayan calendar. Perhaps we have two ancient calendars beginning new cycles.

In depicting the cycle of the moon, we have accounted for 32 of the 69 dots identified by Mr Marshack. Next we will identify the five planets.


Image Credits:

Possible Origin of the Yīn Symbol: Lynn Fawcett, January 2014: After Photo: Sunset and Moonset at 2008 Equinox: Juan Carlos Casado: TWAN: The World at Night: Source: http://twanight.org/newTWAN/photos.asp?ID=3001347: Accessed: 11 July 2013

Schematic rendition of the engraved marks on the bone from the Abri Blanchard as determined by microscopic analysis, indicating the differences in the engraving points and the strokes structuring the serpentine form: Alexander Marshack, 1972: The Roots of Civilization: The Cognitive Beginnings of Man’s First Art, Symbol and Notation, p.48, Fig. 9: Weidenfeld and Nicholson: © President and Fellows of Harvard College, Peabody Museum of Archaeology and Ethnology: Courtesy of the Peabody Museum of Archaeology and Ethnology: Peabody ID Number: 2005.16.1.318.57: Schematic Rendition of the Incised Design on a Carved Bone Fragment: https://www.peabody.harvard.edu/


1. Data for dates and phases of the moon from Time and Date: Moonrise and Moonset in Bordeaux: http://www.timeanddate.com/worldclock/astronomy.html?n=328&month=2&year=2013&obj=moon&afl=-1&day=1: Accessed 11 July 2013

2. Solar Calculator 2.2: iesmith.net Photography: http://www.iesmith.net/tools/solarcalc.html: Accessed: 11 July 2013