Wednesday, October 07, 2009

Water level question rises again.

The question of water levels on Georgian Bay in the 1600s has been debated on this blog before and there are numerous comments attached to these posts.

On reviewing these comments it is noted and acknowledged that much of the discussion has been based on references that might be considered more speculation than science. Most references related to the water level of the river that past the palisades of Ste Marie Among the Hurons from the Wye Marsh and by a short distance into Georgian Bay.

At the time of the earlier posts and comments this author was speculating on water levels of up to 180 meters on the Wye River. Comments were varied but one participant stated that this level would have swamped Ste Marie and went on to say that the water levels of the 1600s were basically the same as they are today. Upon running the 180 mter contour line in various mapping programs and with some attempts with a GPS 180 meters did appear a little high but the physical features of the shoreline and the reconstructed historic site still indicated to me that higher water levels were indicated at the time this establishment existed (1639 - 1649). Upon further research and a study (Roger Chittenden 1990) commission by the Wye Marsh it would appear that while my previously speculated water level of 180 meters was indeed high and may well have swamped Ste Marie, it was substantially higher in the 1600s than now. The 1990 report referenced in a publication"Before and Beyond Ste Marie" (available at Ste Marie and the Huronia Museum in Midland) clearly indicates a water level of 11 ft higher than that of today. Others reference this report as stating a 3 meter or about 10ft decrease in water levels in the Wye Marsh or on the Wye River since the time of Ste Marie's construction. Given that chart datum on Georgian Bay is stated as 175.9 meters by adding 10 ft we arrive at 178.9 meters. When a 178 meter contour line is applied to the mapping of this part of Georgian Bay and the Wye River at Ste Marie it runs almost parallel to the existing palisades that define the western parameter of this current site. From primary source documentation and archaeological research there are indications that at times Ste Marie was wet to the point of requiring drainage ditches that were most likely also used for the canoe access into the interior of this establishment and therefore the locks described and constructed at the direction of by Wilf Jury (manager of this reconstruction project) are a misconception.

Aside from the interpretation at Ste Marie, the water levels of Georgian Bay being higher by 3 meters or so during this historic period effect where we may look for the evidence of the landing places of historic figures such as Champlain, Le Carron, Sagard and the Jesuits. Finding these landing places also may change where we look for the historic villages that were serviced by these landing places. A rise of 3 meters at the head of most bays and the mouth of most rivers in Huronia has a significant impact on the navigation that was possible and how far back from the current shoreline these villages may have existed.

So in conclusion, I will agree that the water levels at the time of first contact in Huronia may never have reached the 180 meter contour line that I had speculated on but that they were significantly higher than today and that a contour line of 178 meters may well be used to define our shoreline search.


Gibson, William said...

While standing in Georgian Bay this afternoon, boy, was the air hot and the bay cool, my mind wandered over the question of lake levels. I wonder if the site of Ste. Marie II at Christian Island offers any further hint about the 1649 lake level. I have never visited there, so I am not sure where the site is in relation to the current bay level let alone to a suspected higher bay level in the 17th century. Who has any information to offer on this?

flaxspinweav said...

I have been to Ste Marie Ii on Christian Is. I cant add anything specific about water levels as such, only that the site of the remains, which consists of overgrow partial rock walls now, is not close to the shoreline to my recollection.
Wendy Maurice