Sundials - World's Oldest Clocks

North American Sundial Society

nass_news_2012_apr_GardomEdgeMonolith
Gardom Edge Monolith
[photo courtesy of Dan Brown, Nottingham Trent University]

A two meter standing stone at Gardom’s Edge may be an astronomically aligned monolith set up during the Neolithic period 2,500 – 1,500 BCE to recognize the summer solstice.   According to Dan Brown, Andy Alder and Elizabeth Bemand of Nottingham Trent University, “Such an astronomically aligned stone could be described as a seasonal sundial … However it is not intending to mark local time during a day or measure exact dates during a year.  Rather the seasonal shadow casting allows for the display of cosmological knowledge such as the ‘death’ and ‘rebirth’ of the Sun”…

The upward facing north slope of the stone remains in shadow until near the time of Summer solstice.  Today the stone points south at an upward tilt of 58.3° +/- 2.9°, seemingly aimed at the highest rise of the summer sun, computed for the Gardom Edge latitude of 53.26° as 60.7° in Neolithic times.

Was this a single day’s observance?  The researchers have carried out 3-D computer modeling of sunlight on the upper edge of the stone through the seasons, adapting for changes in the Earth’s ecliptic plane back four millennia.  As they calculate, depending upon the angle of the stone, not only could it be completely illuminated at solstice, the top edge could have been in light for several hours before and after solstice. 

The researchers conclude, “Given its uniqueness as one of the few single standing stones in this region, this idea [of astronomical alignment] cannot be confirmed through comparison with other sites close by.  This fact makes it challenging to rule out chance alignment of the stone that could seem to create a seasonal sundial.”

Nevertheless, the presence of packing stones at the base of the monolith indicate intentional stone alignment.  “Other examples of shadow casting in the British Isles have also demonstrated that the skills were present at this time including the symbolic importance.”

Download Research Paper: http://arxiv.org/abs/1203.0947