540 ON THE PHENOGAMIC VEGETATION OF 
Dee, may be traced, the one to the summit of Ben Vrotan, 
the other to a hill about half way between Castletown of 
Braemar and Blair of Atholl, but more to the north-east 
than the central point of a line drawn between these two 
places. The latter of these streams, named the Geonly, is 
somewhat tinged with the brown colour which the rivers 
and lakes of peaty districts commonly assume ; but that 
from Ben Vrotan and Glen Dee is pure and limpid, which 
is the case with all the other streams from the glens open- 
ing on the north side of the valley of the Dee, as far as 
Castletown. The mountains of Braemar being granitic, 
and but thinly covered with soil, their streamlets are clear, 
and the Dee passing in the whole of its course through a 
country covered with granitic diluvium, and but scantily 
supplied with coloured alluvium or soil, preserves this clear- 
ness throughout. Its whole course is about 75 miles. 
The Dee is decidedly alpine in the upper half of its 
course ; and from the sterility of the neighbouring country, 
the absence of mud in its bed, and the rapidity of its cur- 
rent, it manifests much of this character all along, several 
of the alpine plants being found on its pebbly beaches, even 
as low as within three miles of its mouth. It has no falls 
in its course, excepting that of the Linn, in Braemar, which 
is produced by the narrowness of its channel at this place, 
apparently an irregular crack in the mica-slate, rather than 
by a sudden alteration in the altitude of its bed. A few 
rapids occur, such as those below Invercauld, and at the 
Bridge of Pitarch. It has, however, no muddy pools of any 
extent, but uniformly flows with a rapid stream, more or 
less rippled as the bed happens to vary from pebbly to 
rocky. 
From its source to the Pass of TuUoch, 38 miles from 
Aberdeen, the Dee flows in a narrow, and but slightly tor- 
tuous valley, bounded on both sides by mountains of mode- 
