NATURAL HISTORY OF THE BANKS OF THE TAY. 
51 
districts is, for the most part, marshland lying between the water and 
the banks. 
This section extends from the mouth of the Almond to a little 
above Newburgh on the one side, and to Invergowrie on the other. 
The right bank is about 9 miles in length, and the left bank 20 miles. 
Some of the characteristics of these districts may be described at 
greater length. 
In the Highland district the river has a generally rapid course 
(over a pebbly bed) through the valleys of the Silurian hills. The 
banks vary considerably—in some places rising more or less steeply 
from the water’s edge, in others spreading out into wude cultivated or 
uncultivated haughlands, sandy, shingly, or marshy in their nature. 
There are several islands and a few backwaters. The larger affluents 
are the Lyon, Tummel, and Braan. These have all rapid courses in 
pebbly or rocky beds through Silurian valleys, and drain a very large 
area. 
In the Strathmore district, the river, after crossing the “ Great 
Fault” in the conglomerate belt, takes its course through the great 
plain of the Old Red Sandstone formation. The current is generally 
rapid, and the bed pebbly. The character of the banks varies con¬ 
siderably, in the same way as in the Highland district. Several trap- 
dykes intersect the course of the stream, and there are several islands 
and backwaters. There is only one large affluent, the Isla, whose 
current is not very rapid in its lower course, and whose bed is thus 
rather muddy. 
The Tidal District is—as its name implies—the tidal part of the 
river, and is also in the Old Red Sandstone formation. For the first 
2^ or 3 miles the bed is pebbly, but below Perth it becomes muddy. 
The current is, on the whole, rather rapid at low water. There are 
two large affluents, the Almond, a rapid stream, and the Earn, a 
somewhat muddy and slow running river. There are 7 or 8 islands 
(3 of wfflich have been converted into peninsulas), and, in the lower 
part of the district, a number of mud and sand banks, covered at high 
water. The character of the banks for the first 2 or 3 miles is some¬ 
what like that in the middle district, but below Perth there is a 
change. The banks (of Carse clay) are often comparatively high and 
steep, but between them and the river there is, at low water, a fringe, 
often of considerable width, of marsh—fresh in the upper stretches, 
salt in the lower—more or less completely flooded at every tide. 
Stony and pebbly shores are /;^frequent in this district. 
Some other things which probably affect the distribution of the 
plants require to be briefly noticed. 
Salinity of the river water.—Statistics regarding that portion of 
the river which comes within the scope of this paper are non-existent. 
