NATURAL HISTORY OF THE BANKS OF THE TAY. 
determine these sudden changes of direction. The westward portion 
of the Perthshire Highlands is trenched by a series of longitudinal 
valleys running more or less east and west. These are the valleys of 
the Earn, the Almond, the Bran, the Tay, the Lyon, and the Tummel. 
These valleys are terminated at their eastern extremities by a great 
transverse valley, running north-east and south-west, and cutting them 
off nearly at right angles. Through this valley flows the Garry, and 
as it passes on it gathers up the waters of each of the longitudinal 
valleys in turn, carrying them southward in a combined stream. 
This transverse valley terminates at Dunkeld, where the river emerges 
from the Highlands, but although it takes advantage of its new-found 
freedom to assume a more winding track, its main direction continues 
the same until it reaches Perth. Here, however, it meets with a 
formidable barrier in the Sidlaw range, and although it has succeeded 
in forcing a passage for itself between the hills of Kinnoull and 
Moncreiffe, the achievement has been at the expense of shortening it 
course, because the elTort has effectually bent its direction eastward 
along the shortest possible route to the sea. 
AGRICULTURAL. 
But a more important division of the river is the AgriciiLturaL 
Under this aspect it divides itself naturally into two sections—the 
Highland and the Lowland, and Dunkeld may be considered as the 
meeting-point of the two. North of Dunkeld the Tay flows through 
valleys more or less narrow and bound in by lofty hills. Here is the 
resort of the artist, the tourist, the health and pleasure seeker; and 
here are situated the mountain reservoirs which feed and support it. 
But the occupation of the farmer is of secondary importance on 
account of the steepness of the slopes preventing formation of soil. 
Crops there are where the valley widens so as to admit of floor space 
sufficient to collect enough soil for cultivation, but as a whole, the 
highland part of the Tay basin cannot properly be termed agricultural 
land. After passing Dunkeld the river enters and traverses the A"ale 
of Strathmore, and again after crossing the Sidlaws, makes its way 
along the Carse of Gowrie. These two broad level expanses in 
contrast with the Highlands are devoted almost exclusively to agricul¬ 
ture, and the many thriving farms and orchards dotted about through¬ 
out their extent testify to the depth and fertility of the soil which has 
accumulated. But it is to the river flowing through them that these 
results are due. The river is necessary now for purposes of irrigation 
and drainage, but it has in the past served the far more important 
function of grinding down rocks into soil, bringing it to the low land, 
and depositing it where it now lies. Age after age the Tay has 
wandered about from side to side of these two plains, building up its 
