Here is a short video I made today about this problem. It was first brought to my attention by John Ball of South Dakota State University last winter. I have found several cases of it in various places and with several types of fabric. This video was made at Ft. Stevenson State Park, Garrison, ND.
Hope you find it helpful.
<iframe width="420" height="315" src="//www.youtube.com/embed/nwkJOtzuEIc" frameborder="0" allowfullscreen></iframe>
Hope you find it helpful.
<iframe width="420" height="315" src="//www.youtube.com/embed/nwkJOtzuEIc" frameborder="0" allowfullscreen></iframe>