Old Moss and the Glacier

Every year the terminus of the glacier is measured where the ice meets the rock in the backyard. The line is recorded using a very fancy, centimeter accurate backpack GPS. The red line on the right is from this year. The yellow line is last year. The glacier receded on average 8 meters in the last year. 

In some areas where the glacier has receded it has exposed old moss beds from before the last mini ice age when these rocks were last exposed to the air. The moss beds nearest the glacier have been dated to be from around 800 years ago, getter younger the further from the glacier you find them. It took the glacier about 400 years extend itself from the moss patch pictured below near the terminus to the moss patch they found near station. The glacier has taken about 60 years to recede from station to where it currently sits about 600 meters away.

One day 800 years ago this moss had been happily growing for several hundred years (probably) and then one winter it snowed and in the spring it did not melt. Over years snow accumulated and compacted and over time it became part of the glacier. The moss bed was then preserved under the ice, never having seen open air or the sun for 800 or so years. My foot also in the picture above for scale. 

The moss bits are still very well preserved even though they have been dead for almost a millennia.