Each skein is hand dyed in Anchorage, Alaska by Northern Bee Studio exclusively for the Wooly Mammoth.
A "sock blank" is a preknitted fabric that is then dyed to be knitted from a normal skein of yarn. Knit straight from the blank into your knitted masterpiece and enjoy the sleek gradient color scheme. 
An example is shown above.
75% Superwash Merino, 25% Nylon
460yards/100g, Fingering Weight.