LUCAS : VESTIGES OF ANCIENT FOREST. 
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such as may be seen on the west coast of Norway at the present 
day. The upper parts of the moorland gills, and much of what is 
now the moors, must formerly have made a beautiful appearance 
with its light gauze-like forest of Birch and Mountain Ash. The 
last surviving example, on any considerable scale, is preserved in 
Birk Gill, a tributary of the river Burn, which runs N.W. to S.E. 
The Gill is about 400 feet deep at its mouth (the bottom of which is 
600 feet above the sea), and half a mile wide from ridge to ridge. 
Like all other valleys at the same elevation in these hills, it is boat- 
shaped in section, the beck running in a deep ravine at the 
bottom. There is no cultivation in the Gill, the sides of which 
are wild heathery moorland, crowned with fine lines of crags 
down to the edge of this ravine, in which the native forest is 
preserved. The belt of wood clothes the sides for 200 feet or up 
to 800 feet near its mouth, and ends where the beck reaches 900 
feet, in a distance of rather over a mile. Above this point the 
stream is called Barnley Beck. The wood consists of Mountain 
Ash, Alder, Oak, Ash, Birch, Holly, and Thorn, and runs above 
the edge of the cleft with a delightfully irregular and feathery 
margin, on to the ling- covered moor. Above 900 feet the strag- 
glers were all noted, the highest living individuals of each kind of 
tree being as follows. (The full details of all the observations 
will be found in my " Studies in Nidderdale," xiv. 3. Thorpe, 
Pateley Bridge.) Barnley Beck, S.W. and N.E.— Oak, 900; 
Alder, 950; Salix, 1050; Thorn, 1080; Birch, 1125; Holly, 
1150; M. Ash, 1175. Scale Gill, tributary of Barnley Beck, 
N.W. and S.E. — Thorn, 1100 ; M. Ash, 1175, highest living tree. 
The Gills in Colsterdale present a similar picture. House Gill 
M. Ash, 1150, highest living tree. New House Gill — M. Ash, 
1175. River Burn — Thorn, 1175, on tongue at junction of Long 
Gill. Long Gill — Birch, 1175 ; M. Ash, 1250, highest living tree. 
Backstone Gill — M. Ash, 1275, highest living tree. Steel House 
QUI — M. Ash, 1375 ; Bullace, 1375 ; together on Moor, at edge 
of Gill. Thorny Grein — M. Ash, 1200, highest living tree. 
