South of Delta Junction, AK there are many glaciers. One of them lies at mile 218 and a hike up Castner Creek brings you to its end (the terminal moraine). Once you climb up onto the glacier you are standing on hundreds (or thousands) of years of snow and sediment trapped there. Castner glacier is rapidly receding and as it melts has created many stunning and several exceptional ice caves. The caves often reach far back and are sculpted in inconceivable ways. As you stand there in the chill of the cave and stare into the crystal-clear ice, it is impossible to grasp it all!
To get at the size and beauty of these caves, I’ve compiled this video of the walk-through of just two of the ice caves. Sorry for a some instability, but the floors were very slippery, and I had to protect my camera in case I fell 🙂
Apart from the beauty of the caves the geology of them is truly remarkable. For instance, consider the images here. The ice is so clear that you can see several inches back into it revealing layers of suspended soil.It’s hard for me to say how long they have been trapped in their icy tomb!
As the glacier melts the suspended sand particles fall out. They form layered domes and peaks which can be be many feet tall. Here’s a small deposited pile in the mouth of the eastern Castner Ice cave.
There were two caves that I explored with Ross, each were double ended; you could enter through the front and exit in the back. The walls were sculpted by water and wind. Ross commented that it was though “a huge tsunami had just been frozen instantly” – a apt description! It is so hard to judge the size of these caves without scale, so you’ll often see a person just to understand how big they are!
Being on this glacier was really special for me. I guess because I suddenly understood all the years of school where we talked about the features of glaciers and their impact on the landscape. To see the suspended sediment in them made it clear how areas like my hometown (with sandy, loose soils) could be laid down by receding glaciers. The importance of the active ends of glaciers (the terminal moraine) were apparent because the river was actively fed by the glacier. And, last, you really can’t imagine how huge they are till you stand on top of one! Or hike across it.
One last piece of the hike was a very cool look at a feeding white-tailed ptarmigan. Ptarmigan are notoriously “fearless” of humans (some describe it as stupidity), so this guy had little problem with us approaching him. He waddled around and ate snow an picked at willows. They are incredibly beautiful in the winter! But I imagine this bird will be molting to his summer brown soon 🙂