We all know it’s winter outside by the snow and the cold temperatures. But when you’re underground, it’s a different story.
How cold does it get in a mine? With the cold spell that Sudbury experienced in early 2012, one of the mine exits at Dynamic Earth had cold air pouring in, making it colder than -10˚C. As a result, the ground froze over, but the air near the ceiling of the mine stayed above zero. The water seeping through the rock dripped from the warmer ceiling onto the frozen floor – where “ice stalagmites” grew drop by drop. In these conditions, their counterparts –the stalactites that hang from the ceiling – never formed.
The tallest stalagmite is 1.07 meters high. They get shorter as one continues into the mine. There are no more stalagmites after 40 meters, an indication of increasing temperatures as one moves through the mine. As seen in the pictures, the location and relative sizes of the stalagmites are mapping out the pattern of dripping frequency in the mine drifts: The more it drips, the taller the stalagmite. This is just another reminder that we have plenty of cracks in the rock above us.
Ice stalagmites are quite common at the entrance area of abandoned mines or caves. However, unlike the much deeper production mines in the Sudbury area, Dynamic Earth’s visitor mine is only 20 meters below the surface. Despite the much shallower depth, the average temperature in the visitor mine stays at a hospitable 5˚C.
Even though Dynamic Earth is closed to the general public during the winter months, schools are encouraged to book into our programs: your class will likely be able to witness the wondrous stalagmites on an Underground Tour. Occasionally, even a layer of fog can be observed close to the ceiling of the drifts – another underground winter feature!
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