Thread: As the high mountain ice melts back, archaeological finds from the ice become older and older. The earliest archaeological finds from the ice in Norway are now five fragmented arrowshafts dating back to 4000 BC (one in picture). How old can the finds get? /1 
Is it possible that future melting could reveal archaeological finds that date back to the last Ice Age, as envisaged in this prophetic cartoon by Gary Larsson? Could we find remains of Ice age hunters at the bottom of the ice? /2
Surprisingly perhaps, and contrary to popular belief, the ice in the high mountains does not date all the way back to the last Ice Age. Most mountain ice in the Northern Hemisphere has a maximum age of 7000-9000 years. /3
Why is the ice not older? The answer to that is a warm climatic period called the Holocene Thermal Optimum, which took place 7000-9000 years ago. Studies of mountain glaciers tell us that most of the ice melted completely away during this warm period. /4
The Holocene Thermal Optimum in the Northern Hemisphere was caused by small and gradual changes in the Earth’s orbit around the sun. When the optimum faded, the ice in the high mountains started coming back. /5
This happened around 7000 years ago in Norway and somewhat earlier in western North America. A few hundred years after the onset of the new glaciation, some of the ice had become large enough to start moving – the glaciers were back. /6
Since then the ice has expanded and contracted according to climatic conditions. The ice in Norway reached its largest extent during the Little Ice Age (AD 1550-1850), and has melted back since then. The melting has been especially marked in the first years of the 21st century /7
Based on the age of the finds, we are now back to levels of ice last seen 6000 years ago. So, with a maximum age of mountain ice at c. 9000-7000 years before present, we should not expect to finds organic artefacts from the ice older than this? Well, things are not so simple. /8
The vast majority of finds post-date the neo-glaciation (7000 years before present in Europe and 9000 years before present in western North America), but there are a few earlier finds in North America, which are puzzling. /9
The glacial archaeologists in Yukon have radiocarbon-dated all their recovered artefacts. The earliest, a fragmented dart shaft for an atlatl, is c. 9400 years old (read more here: tc.gov.yk.ca/publications/A… @northernpapa /10
There is even a more than 10.000 year old dart from the Rocky Mountains (held by our colleague Craig Lee in the picture), which was lost during the Holocene Thermal Optimum there. How did these very old artefacts survive for so long? /11
Did the ice where these artifacts were found survive the Holocene Thermal Optimum? Or can the wooden artefacts survive for longer periods outside the ice because of the cold environment at high elevations? At the moment, we do not know for sure. /12
The combination of sustained cold, wind and high altitude does lead to a gradual freeze-drying of artifacts; a kind of natural conservation. This may be what saved the few lucky very early artifacts from the ice. /13
Even with the exceptional preservation of these few early ice artefacts from North America, chances are very small that we will see Ice Age organic artefacts appearing in the next decades as the melting of mountain ice continues. /14
Summing up, it is unlikely that Gary Larson’s prophecy will become true. There will be no Ice Age caveman at the bottom of the melting ice. So, what secret is waiting for us when the high mountain ice has melted away? /End
