PROCEEDINGS OF THE PERTHSHIRE SOCIETY OF NATURAL SCIENCE. 
25 
others. He may think them to be matters commonplace, 
and unworthy to be brought before the notice of the 
Society; but in the investigation of Nature no facts are 
worthless, if they be accurately observed and faithfully re¬ 
ported. The observers may not be able to draw from the 
facts all the conclusions which they warrant, but still, as 
far as the facts go, they have a value; and if members of 
the Society could be induced to observe, and report their 
observations, the papers would have a still more varied 
character, and would awaken a still greater interest. 
I wish you to accompany me on a walk along the River 
Almond downwards for about a mile and a-half, beginning 
at Lynedoch. We first strike the river just above the site 
on which Lynedoch Cottage formerly stood, and we find 
that we have reached the stream at a place where it forms 
a long, broad, deep pool. Even in the driest season of the 
year, when the water in the river channel has shrunk to a 
rivulet, the water in the pool has an average depth of 10 
feet. It is so still that you can scarcely detect the flow of 
the current; but below it and a little way above it, the 
stream is comparatively shallow, sweeping with a current 
more or less rapid over the stones and round the boulders 
that lie in the watercourse. Such is the difference which 
strikes the eye at once; let us try if we can ascertain its 
cause. If we go a few yards up the stream, we find an 
immense mass of trap forming the southern bank, and ris¬ 
ing to a great height in a wooded knoll. If we are 
interested in the etymology of the names of places, we can 
see that the ridge formed by the trap must have presented 
very much its present appearance to the earliest Celtic 
inhabitants, for they called the spot Drumcairn, and it 
still bears its accurately descriptive appellation. The river 
has here first encountered this mass of trap, but finding 
the immense impediment too hard to be overcome, it 
slightly altered its course to the north, cutting a channel 
through the softer Old Red Sandstone in the vicinity of the 
trap. Soon altering its course slightly to the south, it has 
encountered the trap-dyke further down at a right angle at 
a more vulnerable point, and has there overcome the 
obstacle presented. The trap-dyke where the river cuts it 
is about 48 feet in breadth. The rock which the trap has 
pierced is Old Red Sandstone. The sides of the rock in contact 
with the trap are smooth and glazed and intensely hard. 
This induration is very marked both above and below the 
dyke, but decreases as we recede, until the rock resumes 
its normal appearance. As we look up the stream, we see 
that the current is broken by a fall, not where the stream 
crosses the dyke, but upwards of 30 feet above it; as we 
look down the stream, we see that the deep pool is not at 
the dyke, but is upwards of 30 feet below it, though in the 
narrow channel—in which water is continually running 
even in the driest periods of the year—the rock has been 
worn away to within six feet of the dyke. Can we explain 
those phenomena? The stream in flowing to the sea had to 
cut through this mass of trap and hardened sandstone. 
The softer rock down the stream has been worn away by 
the action of the water much more rapidly than the 
whinstone dyke and the indurated sand-stone in its 
immediate vicinity. Hence we have the deep pool 
below, and the hardened rocks, trap-dyke, and nar¬ 
row channel above. I have already said that the sand¬ 
stone has not yet been worn away up to the dyke, but the 
wearing process is slowly and continuously advancing, and 
can in some parts be seen to great advantage. The layers 
are of different degrees of hardness. Sometimes a layer 
of softer texture is surmounted by a layer of harder mate¬ 
rial. The water has washed away the lower, and has left 
the upper layer overhanging without support. This un¬ 
supported portion falls away in larger or smaller pieces,— 
and in this way the sandstone is gradually retreating 
towards the dyke. 
Having examined the dyke which crosses the course of 
the Almond at this spot, and the effects which it has pro¬ 
duced, let us walk down the riverside for about a mile, 
when we reach Dalcrue. Here, too, we see how expressive 
and true to nature the old names of places are. Those 
who first called the spot Dalcrue must have seen in it the 
same physical features that now present themselves to us 
—the deep river gorge and the steep wooded banks. The 
scene from the bridge which here spans the river is ex¬ 
quisitely lovely. On one side a view opens up of wood 
and glade, spacious parks and glancing water leading up to 
a spur of the Grampians; on the other side we look down 
into a deep dell, through which the river is flowing be¬ 
tween high and nobly wooded banks. After gazing on the 
distant view let us look over the bridge, first on the one 
side and then on the other. Looking down from the upper 
side of the bridge, we see a comparatively shallow (of 
course I speak of the Almond in its ordinary condition), 
broad stream running over a stony channel. Looking 
down from the lower side, we see an immense deep black 
pool reaching far down the river. We have here exactly 
the same phenomenon that we saw up at Lynedoch. If 
we turn to the east, we see right before us a bold bluff 
precipice of Old Red Sandstone rising sheer up from the 
road at the end of the bridge. A cursory glance enables 
us to see that the sandstone is traversed by a trap-dyke 
about 38 feet in breadth. Here, too, the trap has left 
evident marks of its intense state of heat. The glazed face 
of the sandstone in contact with it, its hardness in 
