Moments of ah ha, moments of D’oh!

Some days I have moments of ah ha with my job.

Ah Ha!
Ah Ha!

Other days I have plenty of self-inflicted D’oh moments!


Last week I had several moments of both ah ha and D’oh in the same afternoon. In my last post, I told you about how the Provincial Archaeology Office tried to relocate some of the older sites in the inventory the old-fashioned way; by going out into the field and finding them. This week I am going to share with you a similar post, except this time we are going to use some newer technology to relocate some sites.

In 2011, I wrote two blog posts on the Intermediate Period in North West River and Sheshatshiu. The first post focused on Dr. William Fitzhugh’s work in NWR. Fitzhugh spent two field seasons, 1968 & 1969, working in the Hamilton Inlet area of Labrador. For those of you who don’t know Dr. William Fitzhugh is the Director of The Arctic Studies Center at the Smithsonian National Museum of Natural History. He used this information to write his PhD thesis: Environmental Archeology and Cultural Systems in Hamilton Inlet, Labrador: A Survey of the Central Labrador Coast from 3000 B.C. to the Present. In his thesis, Fitzhugh provided this map showing the location of his sites:

Red dots show the location of the sites found by Dr. Fitzhugh
Red dots show the location of the sites found by Dr. Fitzhugh

The Provincial Archaeology Office did not exist in 1968-69. Therefore, Fitzhugh’s site location information was not transferred to the maps used to keep track of site locations. In the ensuing years since 1968-69, many things have changed in NWR to the point where it is now hard to rectify Fitzhugh’s site locations with what the community looks like today. Because of not having transferred Fitzhugh’s site data, we could not confidently plot his sites. We knew they were in NWR but we could not say accurately where they were. Essentially the sites were displayed in our ArcGIS system as something like two starbursts; essentially, we had two sets of coordinates for more than 35 sites.

PAO site locations for Fitzhugh's sites in NWR
PAO site locations for Fitzhugh’s sites in NWR

When I wrote the posts on the Intermediate Period in 2011, I tried to georectify Fitzhugh’s map with the PAO topographic map in ArcGIS. Georectify means to align digitally a satellite or aerial image with a map of the same area. In georectification, the images are layered on top of one another and a number of corresponding control points, such as street intersections, are marked on both the image and the map. These locations become reference points in the subsequent processing of the image. The GIS software then warps the images so they fit together and overlap exactly. When I tried to georectify the above maps I was not able to get enough control points so I couldn’t get the images to line up properly and therefore I could not accurately plot the sites.

First georectify attempt
First georectification attempt

As you can see, particularly from the shoreline in the upper left corner, the maps did not line up. Part of my problem was that I could not get enough control points and I used one control point that was actually way off. There is a small wharf just above the letter ‘H’ in NORTH on Fitzhugh’s map. I assumed incorrectly that this wharf lined up with the wharf on the colour PAO map that is just above the letter ‘N’ in North.

I recently had reason to go back to trying this georectification exercise for Fitzhugh’s NWR sites. That’s when I had both a moment of ah ha and a moment of D’oh! It occurred to me that I could retry this georectification exercise or I could just email Dr. Fitzhugh and ask him if he had a decent map or perhaps even coordinates for his sites. My ah ha moment! Please see the kid in the red shirt above. My next thought was, well, why had no one thought of that before now? My D’oh moment, please see Homer.

Within an hour or two, Dr. Fitzhugh responded to my email, unfortunately, he was not able to help with a better map or coordinates. Archaeology in 1968-69 was conducted very differently than it is today. While he couldn’t supply any information, something he said in his email was very helpful; he stated that he “…used the air photo to produce the map…” Looking at his map, the air photo was inset at the bottom left corner. Well, of course, the map was based on the air photo, why hadn’t I realized that before? A Homer moment, D’oh! Looking through our collection of air photos, I realized we had one that dated to around the same time. Looking closely at the air photo I realized that the wharf that I had been using as a control point on our colour map was not the same as the one on the Fitzhugh map. I scanned the air photo and enlarged it. (Unlike all the CSI episodes I have ever seen, the photo became grainier as I enlarged it, not clearer!) However, I was able to make out details on the air photo that I could line up on Fitzhugh’s map such as clearings and roads/paths. Then I saw the wharf in the air photo that Fitzhugh had drawn on his map and realized just how far off I was. So I loaded both into ArcGIS, selected my control points and they aligned very nicely.

Air photo top left, Fitzhugh map bottom right.
Air photo top left, Fitzhugh map bottom right. Red polygons are clearings, yellow lines are roads/paths, and green oval is the wharf
Top to bottom
Top to bottom. In this series of photos, Fitzhugh’s map is lined up over the air photo. Going from top to bottom I peel back Fitzhugh’s map revealing the air photo underneath and showing how the map lines up with the clearings, road/paths and wharf on the air photo

Then I tried to line up the air photo with the colour map. I had no problem with that because I was able to line up the wharf in the correct spot and I was able to line up some roads/paths and the shoreline. Then I had an ah ha moment, if I can do that then I can line up Fitzhugh’s map with the air photo!

Air photo and colour map lined up
Air photo and colour map lined up

Now I was finally able to line up Fitzhugh’s map with the PAO colour map and thereby more accurately plot his sites!

Fitzhugh's map lined up with the air photo which is lined up with the colour map
There are three layers in this photo; Fitzhugh’s map lined up with the air photo which is lined up with the colour map
Finished PAO map with the site plotted
Finished PAO map with the sites plotted

The sites now seem to be spread out on the land as opposed to how they are dispersed on the first colour PAO map in this post, two starbursts. As an added bonus, I was able to test the accuracy of this new plot by looking at the location of FjCa-29 (the most northerly of Fitzhugh’s sites, near the middle of the map). That site is known as Graveyard Site, it would have been located somewhere within the graveyard that is the white square just below the dot for FjCa-29. Based on the new plot, the current distance of the site from the graveyard is just 20 metres. While this is not as accurate as I would like it to be, it is much better than the old plot.

The benefit of all this is that since we have a better idea of where the sites are we can better protect them and better predict where unknown sites maybe, while allowing development to occur.

12 thoughts on “Moments of ah ha, moments of D’oh!

    1. As I tell everyone who will listen, I am an archaeologist (first) with some knowledge of GIS. The software is amazing, but it can easily be overwhelming.

  1. Hey Steve. Nice job. I wonder if one of the government departments has a modern map of the town that could be used instead, or along with, the NTS map, which doesn’t have all the modern streets and buildings?

    1. Thanks Scott, you mean something just showing the geography without all the cultural stuff, houses roads, buildings etc? Interesting idea, I don’t know.

  2. I first tried this layering technique back in 2004 at Grand Pre, NS when I was plotting artifact types but lacked ArcGIS to enlarge the process. Its too bad because the work is done.

    1. I am an archaeologist with some GIS knowledge. I find using ArcGIS can be tricky but if I stick with it I can get most things to work, the end result is usually worth the effort.

  3. Recently a grave (16th. Century) was discovered in part of my community. (Cape Ray) From what I have read over the years Cape Ray once rivalled Louisburg in trade and was actually given the name,”The little Republic” because of the illicit trade that took place there. After 1744, little or nothing was known what happened to the hundreds of inhabitants that were there. Do you know if any Archaelogist has checked it out?

    1. Hi
      Thanks for the comment.

      I think the grave you are referring to was the one found in 2011, it was likely 19th C – there was no evidence that it was 16th C. (I think there was a newspaper article written about it) Such an early grave would have been huge archaeology news here. Am I wrong? If there was a 16th C grave found in your area I’d love to know about it.

      The Cape Ray area (mostly near the lighthouse) has been surveyed archaeologically since the 60s/70s. In the least few years two archaeological companies have surveyed the rest of the high potential areas in and around Cape Ray and there has never been any trace of anything earlier than 19th C material found, other than the precontact material at the lighthouse.

      If you have information or evidence of a 16th C occupation in the Cape Ray area that would be very interesting.

      1. EMERA is running a Subsea Cable to Nova Scotia from Cape Ray and the area was checked out because of the Dorset Site there. The discovery was made last year. (A Tin Cup from that era was unearthed at the Grave Site) I was at a Community Meeting when the matter was brought up. Maybe EMERA could shed more light on that matter.

      2. Good Morning
        Yip – we are talking about the same burial. There was a miscommunication somewhere, the burial is 19th century. The documentation sent to the Provincial Archaeology Office records the burial as 19th century.

        This sentence is from the report written by the archaeologists working for EMERA: “A preliminary analysis of the recovered material (the glass button in particular) suggests a post mid-nineteenth century date for the burial.”

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s