A few weeks ago I volunteered to help Bernie Taylor, a fellow member of Rose City Astronomers, to investigate whether the so-called “Hancock Woman” pictograph out near Fossil, Oregon might be a solar calendar.
Bernie wrote the book Biological Time and he was kind enough to give me a copy. I have only had time to skim it heavily at this point but I highly recommend it to anyone interested in biological rhythms and the way animal behavior changes during lunar and solar cycles in nature.
Bernie knew that I was going to be at OMSI Camp Hancock Field Station with my telescope the weekend prior to the Autumnal Equinox on 22 Sep 2014. The pictograph is not far from Camp Hancock. He had a question he wanted me to investigate in the field. On the sunrise of the equinox, if you held up a staff in front of the pictograph, would the rising sun cast a shadow down the vertical length of the figure's body? As Bernie explained it to me the idea here is that the shaman would have gone out with his assistant at that time of year watching and waiting for the equinox. Presumably when the shadow falls on the meridian it would signal the time to harvest the crops, time a hunt, or perhaps for some other symbolic purpose. We don't actually know.
We do know that seasonal markers among native peoples of North America is not at all unusual. Some tribes and cultures built very elaborate solar calendars to keep track of the seasons and events. One of the more famous examples is Fajada Butte, a Chaco Culture solar calendar that tracked both solstices and equinoxes with a stunning degree of accuracy. Here's a short (24 second) video showing the phenomenon:
Likewise the Cahokia people constructed a large round red-cedar “Woodhenge” that accurately tracked the seasons. The priest would stand in the middle of the circle and could look due east on the equinoxes to see the sun rise directly over Monks Mound. On the two equinoxes shadows at sunrise will fall directly to the west (and likewise shadows at sunset will fall directly to the east). By watching the shadows he knew exactly when the Vernal and Autumnal Equinox had arrived.
And so armed with Bernie's notes, a hand-drawn map to the site, and a six-foot long staff, on Saturday, 20 Sep 2014 my wife and I trekked out along with OMSI staff and a few members of our astronomy club to scout it out. The two OMSI staff members would do the actual test on the morning of the Autumnal Equinox. For now I wanted to take some photos and do compass measurements to see what was theoretically possible. I have not researched this particular area or the pictograph itself so the Hancock Woman is something of a mystery to me. Here's the wide-view:
The artist used red pigment and probably finger-painted the image. Here are two more shots, one a bright color-enhancement of the pictograph for those like me with red-green color blindness, and the other an untouched close-up of the face:
No one is sure what the strange pictograph illustrates. Is that the sun and the moon? An aura? A god or goddess? Bernie suggests that the "rays" are tick marks counting down the days until the staff's shadow hits the meridian.
We got there about 11:30 PDT. First I took some measurements of the site itself. It's hard to see in the photos but the pictograph is painted on a canyon wall face that runs from SW to NE on a 45 degree angle. (All azimuth bearings I cite will be true north rather than magnetic north.) Right next to it is a predominant cliff jutting out at 170 degrees or almost due south. This figure shows a top-down view of the site:
There is one more detail about the site. To the south is a line of hills that rise about 20 degrees from the horizon. So the rising sun has to clear those hills before first light can strike the staff and cast a shadow on the pictograph. If the staff is positioned directly in front of the pictograph the shadow would be perpendicular to the 45 degree cliff surface (or 135 degrees). I'm using the Sundroid Pro app for the Android OS to determine sunrise, sunset, azimuth, and elevation data. This figure shows the sunrise and sunset geographic north bearings and times for both solstices and equinoxes:
To simplify matters the equinoxes are due east and west (90 and 270 degrees respectively). Note that the actual number for this location is 89.4 and 270.3 but I want to keep this simple. So the question is: at what point does the equinox sun clear the south hills? It turns out that at 08:51 PST the sun will reach an elevation of 20.1 degrees at an azimuth of 112 degrees. This is somewhere between when it rose on the horizon and somewhere short of the Winter Solstice sunrise at 123 degrees. It will not reach the needed 135 degrees until 10:32 PST.
So I'm not sure that an equinox event gets us anywhere. And maybe that's not a surprise. The Northern Paiutes who lived in the area prior to the encroachment of white settlers were nomadic, subsisting on game, pine nuts, and berries in season. The beginning of spring and fall would be important to a farming community but maybe not so much to a hunter-gatherer tribe.
But there was something interesting that happened while we were there. This photo is timestamped at 12:15 PDT where we noticed that the cliff face at 170 degrees acted as a gnomon and was casting a shadow down the middle of the pictograph:
We were all pretty excited by the event. But if you think about it a little bit more it might be nothing. That's because solar noon doesn't occur until 12:54 PDT when the sun reaches 180 degrees at its highest point overhead. There are two events that the natives in the area would be looking for if they wanted to tell time: first light (or sunrise) and solar noon. They did not have clocks and "12:15 PDT" a good 39 minutes prior to solar noon would have no meaning for them.
There's another problem. Because the gnomon is at 170 degrees every day prior to solar noon this shadow effect will occur. The event is only special if it seems to confirm some kind on intentionality on the part of the artist who might have used the natural features of the site to create the shadow effect. Let me back up a bit and ask: what time of year would be most important to natives living in the area? The longest day of the year? Maybe. My first guess was the shortest day of the year. The petroglyph is in the high desert with lots of sun. Many ancient desert cultures paid attention to the shortest day of the year. For example the Babylonians celebrated the annual rebirth of the sun god on the Winter Solstice. Is it feasible that the natives who painted this pictograph wanted to keep track of the shortest day of the year? We can check it:
21 Dec 2014
Sunrise: 07:37 PST at 123 degrees
Sunset: 16:23 PST at 237 degrees
At sunrise the sun is below the southern hills which as I mentioned are about 20 degrees above the horizon. It makes first light on the Winter Solstice when it reaches about 21 degrees elevation at 11:15 PST. By luck, coincidence, or design that is at 170 degrees. The sun moves 5 degrees every 20 minutes:
I checked other dates before and after the Winter Solstice. They are all close. But it is the shortest day of the year where the sun rises over those hills to shine directly on the cliff face "gnomon" that is lined up best. It might just be a coincidence. And this is all based on my compass readings which are far from exact. But I think it would be worth going out to the site on the Winter Solstice to see if at 11:15 PST during first light the shadow crosses the meridian of the pictograph.
[Updated: Many thanks to Dawn Nilson for a correction. An earlier post read "petroglyph" when it should be pictograph. A petroglyph is cut into the rock while a pictogram is painted onto the surface of the rock. Subtle but important distinction. Thanks Dawn!]