"The foaming stream deep-roaring fa's"

The foaming stream deep-roaring fa's, O'erhung wi' fragrant spreading shaws - Burns : The Birks of Aberfeldy.

"Birks" is Scots for birch trees, and the Birks of Aberfeldy is a deep wooded glen. On a mostly wet day we climbed up the glen and walked a section of the Rob Roy Way.