Greetings Bloggers, Sorry to take so long to get this post up. I am sure some of you have been waiting. I had planned to post it yesterday but Maggie (The Boss) had me working in the garden. We have a number of climbing vines up against our fence and I had been given the task of making a trellis out of willow branches. It looks good but the blog has suffered.
This is the massive Ontario sinkhole that I had investigated last weekend. In the middle of the picture you can see me standing in the breakdown. The rock mainly consists of worn slabs of limestone, like raisins in a pudding rounded glacial erratics are jumbled in between. Horizontal strata are exposed in places along the edge of the depression. It is a layer that is intensely corroded.
To me the sink suggests some severe undermining of the forest. There must be some significant water flow in the rock beneath. You can get an idea of the depth by the height of the land in the foreground. It appears that the collapse has taken place along two parallel joints that run off beneath an esker along one direction and up toward the edge of the swamp and the smaller sinkholes along the other direction.
Earlier in the day a friend had speculated on the nature of the underground tunnel system (see previous posts – archived at the right of the screen)saying that because the water was sinking in a known joint near the swamp without a gyre, there must be airflow somewhere other than this spot. As the dried up lake adjacent to this enormous bowl must be swallowed down through the bottom of the depression there is undoubtedly some sort of tunnel system there. This might be the source of the implied air flow.
Several decades ago a scientist explored the area and speculated that the tunnels must be low and wide (following a bedding plane) and by dye tracing suggested that the water rose again at a resurgence a few kilometres away and at a loss of elevation of 17 metres. I am not sure whether he had seen this massive sink but to me I see something a little different than he did.
D thinks that from the wells that overflowed in the nearby town during a heavy storm there must be some sort of artesian effect in play. When the dry lake nearby is draining the passages are likely to be full to overflowing, backing up at the lower end of the system and fountaining out onto the surface.
In mid summer when only a few swampside sinks are functioning the tunnels could well have some air space. This leaves room for cavers. Admittedly the gradient between sink and known resurgence is not all that much but that spring is a pitiful seepage and there is no way that it could account for the water flow that is disappearing; even during dry times. Maybe the known resurgence is just another example of overflow in a “backed up system”.
Both my friend and I are optimistic about an explorable tunnel system. I will keep you posted on the developments. Next step, seek digging permission from the landowner.
OTHER RELATED POSTS ARE ALL FROM MAY 2006
“We Hiked Through a vanishing Lake”
“Creature From The Swamp”
“Tatooed Traveller Explores Ontario”
“Travel Widely and Tread carefully as the Ground is Thin”
“Where the Water Goes”