On Great Dodd this formation is represented by rocks of the Thirlmere Tuff Member, which covers the top of the fell with a thick sheet of welded rhyo-dacitic lapilli-tuff in which the individual pieces of semi-molten lava were flattened under the weight of deposits above them. This rock weathers to a white or pink colour, but it is covered by the smooth grassy turf characteristic of Great Dodd, Watson's Dodd and Stybarrow Dodd, all of which are covered by the same sheet.