76 MR DAVID B. MORRIS ON 
bartonshire portion of the district is a small piece of the 
parish of Cumbernauld drained by early feeders of the 
Bonny, and the Lanarkshire portion consists of two small 
pieces of the parishes of New Monkland and Shotts, which 
are drained by the head waters of the Avon. These pieces 
are so small that I have not taken them into account in 
subsequent calculations. The district from north-west to 
south-east, between the head of Glen Gyle and South Queens- 
ferry, measures 55 miles in length. The breadth averages 
from 15 to 20 miles; the greatest breadth, south-west to 
north-east, being between the source of the Avon and Crook 
of Devon. The area of the district is about 1000 square 
miles. 
GEOLOGY AND PHYSICAL FEATURES. 
The Valley of the Forth is a broad plain, split in the 
east, as by a wedge, by the estuary. On the north the 
plain is bounded by the abrupt line of the Ochils and the 
Braes of Doune. On the south lies the equally abrupt 
plateau, which at its different parts is known as the 
Campsie Fells, the Fintry, Gargunnock, Touch, Denny, and 
Kilsyth Hills. To the west lies the rampart of the High- 
land Hills, through which for a considerable distance the 
Teith and Forth and their early tributaries flow. 
The district is very sharply divided into two by the 
great geological fault which marks the junction of the so- 
called Pre-Cambrian and associated rocks with those of the 
Old Red Sandstone, and which stretches across Scotland in 
a straight line from Stonehaven in the north-east to Rothe- 
say in the south-west. This line enters the Forth Valley to 
the west of Uam Var, passes by Callander and Aberfoyle, 
and leaves the district at the top of the ridge behind 
Balmaha. West of this line the district is “ Highland,” east 
it is “ Lowland,” and in that sense these terms are hereafter 
used. The Highland area is an eroded plateau. The 
valleys and lake basins have been hollowed out, leaving the 
intervening rock masses as groups and chains of hills. 
These hills mostly attain the height of 2000 feet, which 
may be taken as the average height of the plateau. The 
