This image was created by the Canadian Hydrographic service in 1996. Dr. Gordon Fader of the Geological Survey of Canada (Retired) was involved in the production of this survey and has been a valuable resource in our past research efforts of the Oak Island area. He has also become a good and valued friend.

Our base of operations began with this chart. Areas noted on the chart were mapped with sidescan sonar for further investigation. Some areas were also observed with a "tow cam" in tandum with the sidescan so we could also see true video alongside the sonar data.

Proper permits are required in the province of Nova Scotia in order to conduct this work legally, and copies of these are included later on in the presentation.

Interesting to note, that although there are definate artifacts shown on the bathymetry chart, in reality, they may not actually be there. This bathymetric image was completed under contract by a foreign company and they were not interested in taking the processing to a higher level, which would/could have factored out some of the non relavent data. The reason for this is that in order to produce such an image, a mind boggeling amount of data is gathered. Included in this data is information on direction, altitude, speed of sound in the water at that time, etc. Even the activities that were going on on the boat had to be logged. The boat was not a large vessel and effects as minor as a person walking around could affect data as this could change the pitch and roll charactics of the boat. This data has to be properly factured out of the image. From my understanding, much of this was not done as it was not necessary for the level of accuracy of the project. Some of the artifacts shown on the chart could not be located by the sidescan sonar. This could be for several reasons... a couple reasons are quite simple... they are not actually there, and the origional work was a few years old when we began our research and the bottom topography has changed, possibly covering the artifacts. The bottom of Mahone Bay in this area ranges from gravel to large areas of flour like silt. The silt layer can change easily from year to year.

Sample Sidescan imagery - note it is quite different from the Multibeam imagery

Actual sidescan image of the bottom. Darker areas are soft silt, brighter areas are harder areas and rocks.

The sidescan sonar or "towfish" is shown in the center of the image.The dark featureless areas from the towfish to the start of the bottom image on each side is known as the blind spot. A sidescan sonar cannot see directly below itself and this blind spot becomes wider as the sonar is raised off the bottom.