vi PROCEEDINGS—PERTHSHIRE SOCIETY OF NATURAL SCIENCE. 
tioned were not seen in flower, yet on no previous Queen's Birthday 
excursion were so many blossoming plants observed. 
Having reached Stanley by rail, the party walked to Perth along 
the right bank of the Tay. Near Stanley Rubus saxatilis was noticed 
under a hedge by the roadside, a very unusual situation for this plant. 
Near Thistlebridge (or, as it is more commonly called, “Thistlebrig”) 
a quantity of the local Sagi?ia ciliata was found. Here we left the 
road, and, descending to the river, spent a little time in studying the 
geology of the place under the guidance of Mr. Henry Coates, who 
has favoured me with the following account of it:— 
“Thistlebridge'"’ is the appropriate name given to a trap dyke 
which crosses the Tay about a mile below Stanley. It is finely 
exposed in four separate sections, each at different elevations, and 
each of these the party examined in turn. The first is immediately 
above the road, where the sandstone adjoining the dyke presents 
the appearance of vertical bedding. This, however, is due to the 
alteration of the rock, caused by contact with the molten lava. It 
has been baked in such a way as to cause successive joints, parallel 
to the plane of contact. The next section is below the road. Here 
quarrying operations had been carried into the sandstone far enough 
to expose the true dip, showing an inclination of only 15 deg. to¬ 
wards the N.W. The next section occurs at a still lower level, and 
here the dyke has been tunnelled through for the passage of the 
Luncarty Lade. At this point the variation in texture of the basalt 
was well seen, namely, close-grained along the outer surfaces, which 
cooled first, and coarser towards the centre, which took longer to 
cool. The last section was seen in the bed of the river itself to¬ 
wards the east side. Here it forms a most picturesque feature, the 
rampart of black rock, where it projects above the surface of the 
water, contrasting finely with the white foam which marks the sub¬ 
merged portions. The difference in altitude between the highest 
and lowest portions of the dyke gave a striking impression of the 
power of denudation of the river, which must have cut away this 
wall of hard rock to a depth of more than a hundred feet. Looking 
up the river towards Stanley the high cliffs of dark red sandstone 
were seen rising up on the west bank of the river, with occasional 
bands of grit standing out from the softer strata. In the bed of the 
river itself, to the north of the dyke, the outcrop of the strata was 
very distinctly seen, marked by successive lines of ripples. 
Amongst the plants observed at or near Thistlebrig were Valeria- 
nella olitoria , Eupatorium cannabinum, Astragalus glycyphy/los , 
Arabis hirsuta , Saxifraga gra?iu/ata, Malva moschata , and Carex 
pe?idula . The latter is very local and rare in Perthshire, and if we 
had not known of its occurrence near Stanley the plant found on 
this occasion would have puzzled us exceedingly, and been a cause 
of much speculation and exploration. The specimen found was a 
large tuft lying in the Luncarty Mill Lade, and hence evidently 
brought down by the water from the precipitous bank where the 
habitat of the species is. As we continued our course down the 
river many other interesting plants were seen, including Symphytum 
