Okotoks Big Rock – Managing Vandalism with Technology

The word ‘Okotoks’ translates from the Blackfoot language as ‘Big Rock.’ The name was given by the resident indigenous people to a very large boulder that is known as a glacial erratic – boulders that have been moved from their original location by glacial ice. Okotoks is by far the largest erratic in Alberta; it is about the size of a two-story house and is estimated to weigh nearly seven million kilograms. The Big Rock is a well-known landmark in southern Alberta. It is a designated provincial historic resource owned by the Government of Alberta, and is accessible to the public by means of a hiking trail, signage and a parking lot. What is not well-known is that the Okotoks Big Rock has a great deal of Aboriginal rock art painted on its surfaces.

Okotoks Big Rock Erratic

Okotoks Big Rock Erratic

Rock art includes pictographs (paintings) made with a red paint composed of iron-rich hematite (red ochre). The existence of a few red ochre images on the Big Rock has been known for decades, but the revolution in digital photography and image enhancement has brought to light a whole lot more art on the Okotoks erratic than previously known. Specifically, we now know that some areas of the rocks were extensively rubbed with red ochre. Since these red areas lack definable rock art figures like humans and animals, it was long believed that the red blotches were simply part of the rocks’ natural colour. Through enhancement we can now pick out hand prints and finger swipes, telling us these red blotches were indeed made by human beings.

Rock art at Okotoks Big Rock

Rock art at Okotoks Big Rock

Photo-enhanced areas of red ochre smeared on Okotoks Erratic. Note hand prints at top.

Photo-enhanced areas of red ochre smeared on Okotoks Erratic. Note hand prints at top.

All rock art sites are sacred to Native people; rock art represents communication between human beings and the spirit world. Blackfoot people still visit the Okotoks site, conduct ceremonies, and hold the site in great reverence. Thus, it is all the more sad and frustrating that the Okotoks erratic has been subjected to extensive and increasingly frequent bouts of vandalism. As the site is operated by the province and is open to the public, there comes a point where some action needs to be taken. It is an eyesore, an embarrassment and severely disrespectful to the Blackfoot beliefs about the sacred character of the rock. But what can be done with a massive rock surface covered with graffiti that underneath lies fragile, precious painted pictures that tell stories of ancient Aboriginal people?

In the past few years, serious incidences of graffiti were washed off the rock face using a high pressure water sprayer. More recently, an environmentally friendly paint stripper had been used with good success. But critical to any graffiti removal has been potential impact to underlying rock art. We realized that we could never properly manage the site until we had a high-quality “map” of the rocks that plots the complex rock structure and the locations of all the rock art images. We realized that the best way to make a physical record of the Big Rock was to record it in 3D using a portable laser scanner. While documentation won’t stop vandalism at Okotoks, it will make us much better prepared to deal with future instances in a way that protects significant historical resources.

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A partnership with the internationally respected organization CyArk was formed. CyArk is a nonprofit organization dedicated to digital recording and preservation of the world’s most significant sites. Among their credits are 3D recordings of the statues of Easter Island, Pompeii, ancient Thebes, and Mt. Rushmore. CyArk also digitally stores the 3D information for each site, serving as a world archive of heritage data. CyArk retained a local service provider to assist with the equipment and expertise to conduct the laser scanning. In early October 2013 the entire external surface of the Okotoks Big Rock, including the tops of the rocks and some internal crevices, was scanned during two days of field work. The result is a strikingly accurate rendering of the Okotoks erratic in both its geometric shape and the plotting of all known rock art images. The project also resulted in production of an accurate 1:200 scale model of the Rock that will be useful for planning and educational purposes.

3D rendering of point cloud data from laser scan at Okotoks with enhanced photography overlaid. Red areas are red ochre paint; note square-bodied human figure at upper left.

3D rendering of point cloud data from laser scan at Okotoks with enhanced photography overlaid. Red areas are red ochre paint; note square-bodied human figure at upper left.

In addition to the rendering and scale model, the project also raised awareness about negative impacts associated with graffiti and heightening understanding of the value and importance of historic resources to the community. Further Alberta Culture now has a sophisticated tool to use for site management.

Alireza Farrokhi holding 1:200 scale model of the Big Rock

Alireza Farrokhi holding 1:200 scale model of the Big Rock

Sadly, the rocks have already been subjected to more graffiti in the months since our project ended; however, we now have accurate information on the type and location of rock art that will assist in graffiti removal efforts. There are other threats to the cultural and natural significance of the Okotoks erratic. It has long been a favoured place for climbers, subdivisions are rapidly encroaching on the site, and public visitation is increasing. There are many challenges ahead in the long-term management of the Big Rock, but thanks to the careful recording conducted through Innovation Program funding we have a solid baseline of information about this very special place that will guide future management.

Written by: Jack Brink, Curator, Royal Alberta Museum and Alireza Farrokhi, Head of Conservation and Construction Services, Historic Places Stewardship

 

2 comments

  1. This is a very comprehensive survey of the Rock Art problems in Alberta. I hope we can do more digital surveys of rock art as well as glyphs from around the province.

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