184 Tue Bitack WATER OF DEE. 
range on the eastern. It flows through the Loch of Stroan and 
joins its master stream, the River Ken, at Parton Ferry. 
From this point to the sea the combined river takes the name 
of Dee from its tributary water and drops that of Ken, the 
master stream. For the sake of brevity we shall style our 
present-day tributary as the Black Dee or the Cooran Dee. 
I: has two distinct types of topography. These types are :— 
1. The upper portion from its source in the Round Loch of 
the Dungeon down the Cooran Lane to the foot of the 
Loch of Stroan flows swiftly along the bottom of a steep 
walled V-shaped valley. The valley excavation is of 
great depth; consequently it ‘represents a river of 
maturity long before the advent of the Ice Age. 
2. The lower portion escapes with difficulty from Loch Stroan 
outlet, meanders the Mossdale flood-plain, tumbles over 
the Hensol cataract, and finaily steals silently into the 
Ken near Parton Ferry. It does not lie in a deep valley, 
but is only about twelve feet below plain level. It is a 
thing of yesterday—full of contradictions and surprises— 
never in harmony with its channel; undoubtedly it is the 
greatest misfit in Galloway. 
Geological Structure. 
Galloway, in common with the rest of the Southern 
Uplands, is composed almost wholly of hard greywackes 
alternating with softer shales. They represent a deep sea 
deposit of mud and ooze during the Ordovician and Silurian 
Ages. 
These great masses of sediments on the ocean floor were 
finally elevated, subjected to immense pressure from the 
south-east, and thrown into numerous folds. This folded 
plateau stretched from St. Abb’s Head on the North Sea to 
Portpatrick on the Irish Channel. 
During this period of lateral pressure massive cores of 
molten granite rocks were forced or intruded up amongst the 
layers of greywackes and shales. As the ages rolled on and 
continental conditions supervened, the greater portion of these 
paleozoic deposits were removed by sub-aerial denudation. 
Galloway became part of a vast peneplain stretching west- 
