Another theory holds that the name "Brocken" is derived from "bruch", a word used in northern Germany for bog or moor, which commonly used to be spelt as "bruoch" or "brok". It is however doubtful that this fact was primarily responsible for its name. Another possibility is that its name is derived from the fields of boulders strewn over the summit and the slopes of the mountain. This derivation for the name "Brocken" is, however, unlikely because such blockfields are also found on other mountains in the Harz. Moreover, the regions concerned were hardly known at the time when the term was used. Another presumption is based on the reference in a letter written in 1490 by Count Henry of Stolberg-Wernigerode, where he uses the term "Brackenberg". However the suggestion that this referred to old, unusable timber, which was called "bracken", is disputed.