The Mastodons
At the world’s largest surface gypsum mine in Milford, East Hants, the bones of a mastodon were discovered in 1991. Here’s the story of how it ended up there:
209,000 years ago, the area was covered by a glacier. After the glacier melted, there was a lengthy warm period (called an interglacial – the period between glaciers). During this period, which lasted from 125,000 to 79,000 years ago, the climates in Nova Scotia fluctuated from as warm as southern Georgia, United States, to as cold as northern Quebec.
During the last cold phase of the interglacial, mastodons roamed Nova Scotia. We cannot be sure of the exact details but the Milford mastodon was likely walking across a bog when it stepped into a particularly deep spot and sank under its own weight. Mired in the muck, it could not get out and eventually died.
Later, several glaciers passed over the quarry. Glaciers erode land as they move slowly over it, and carry eroded rocks, sand and clay along with them. When glaciers melt/retreat, they deposit the rocks, sand and clay.
The glaciers covered the sinkhole with 30 metres of rock, sand and clay, effectively creating a time capsule that preserved the mastodon’s skeleton until a quarry employee saw its tusk in some fill he was excavating.
The company immediately stopped work and called in scientists from the Nova Scotia Museum who spent the next ten months uncovering the nearly-complete remains of the mastodon. The company stopped working in that area while the archeological dig took place and continued operations elsewhere in the quarry.
At the museum, the bones were cleaned, preserved and catalogued. Over four and a half tonnes of clay-filled boxes were shipped in containers to schools across Nova Scotia. The most intriguing find was by a Grade 6 class from Northport Consolidated School, which found a juvenile painted turtle, with flesh still on its head and front limbs.
Tests on the mastodon’s tooth enamel tell us it was alive about 74,500 years ago. Tests on pollen samples from the sinkhole tell us that the area was a forest with relatively cool temperatures around the time the mastodon lived.
The sinkhole that trapped the mastodon is a common feature of areas with gypsum deposits. Most sinkholes are caused by groundwater naturally eroding rocks like gypsum, salt and limestone which are water-soluble. The water erodes the rock, leaving an underground cavern. Eventually, the weight of the rock and earth above the cavern causes its roof to cave in.
Sinkholes can form either gradually (i.e. a small depression appears and perhaps grows larger over time) or by sudden collapse.
The bones of another mastodon were discovered at the Milford quarry in 1993 and a mastodon skeleton was found at the Little Narrows gypsum quarry, Victoria County, in 2014.
Mastodon Ridge in Stewiacke, which has a reconstruction of a mastodon (pictured below), was named for the bone discoveries in nearby Milford.
There are two schools of thought as to how mastodons fell into extinction around 10,000 years ago: one is that they were hunted into oblivion by humans, the other is that they succumbed to rapid climate change as ice caps rapidly melted across the northern hemisphere. Or maybe both.
The Milford quarry is the world’s largest surface gypsum mine. The company employs about 100 Nova Scotians in Milford and at its dock facility in Bedford Basin.
Reconstruction of a mastodon at Mastodon Ridge.
An upside-down tree in a reclaimed area of the quarry offers a nest to raptors.
The archeological dig in the Milford quarry to uncover the mastodon.
