The Ice Age fascinates me. Tectonic plates take millions of years to change the earth, but a few hundred million tons of ice and water can do it in a few thousand. Or sometimes, if the conditions are just right, things happen a lot faster.
When a glacier melts, the water usually flows away as a stream or river from the base of it. However, if the water is dammed and released, or if something like a volcano causes catastrophic melting, that stream can turn into a devastating flood.
This is what is known as a jökulhlaup (pronounced yoo-kul-hloo-ee-p) or glacial outburst flood. They’re well-known in Iceland (where we get “jökulhlaup” from) because of the numerous glaciers and volcanoes, but can occur anywhere where glaciers exist and can be very dangerous. The 1755 Mýrdalsjökull jökulhlaup may have released more cubic meters of water per second than the Amazon river.
During the last ice age these kinds of massive outbursts were very common. As the planet warmed, immense lakes of meltwater formed in the middle of the retreating glaciers, eventually releasing unimaginably large floods. It’s now accepted that the bizarre geology of the channelled scablands was the result of just a handful of these outbursts.
Jökulhlaups – very dangerous, very interesting.