Glacial Erratic / Day 31 / Letcher, South Dakota / Mile 1,400. Photo by Chris Register/www.conversationswithus.com Glacial Erratic / Day 31 / Letcher, South Dakota / Mile 1,400. Photo by Chris Register/www.conversationswithus.com By Heidi Marttila-Losure January 2, 2017 Glacial Erratic / Day 31 / Letcher, South Dakota / Mile 1,400. Photo by Chris Register/www.conversationswithus.com 2017-01-02 Heidi Marttila-Losure Share ! tweet