THE GEOLOGY OF SOUTH-EASTERN KINCARDINESHIRE. 907 
easterly trend. The dyke described by Professor Forses* belongs to this group. 
First seen in close proximity to the Highland fault in the Burn of Balnakettle, it 
appears again at Coventree quarry, at Phesdo quarry, in several of the gorges on the 
eastern slopes of the Strathfinella hills, in the Rectory quarry, Drumtochty, and finally 
in the Broomy Brae quarry, near Auchinblae—a distance in all of about eight miles. 
Another example, which may be traced for about the same distance, is seen in the 
North Esk, near Capo, in the Luther Water between South Muirton and Luther Bridge, 
near Marykirk station, at the Burn of Balmakelly (where it is at present being quarried 
for road “ metal”), and in a small stream north of Craig of Garvock. Other dykes, 
occurring sporadically and traceable only for short distances, are found at Stonehaven 
harbour, in the Carmont railway cutting, in the North Esk near the House of the Burn, 
at Birnie Road siding, and at Johnshaven. The last example presents features of 
considerable petrographical interest which will be discussed in my paper on the petro- 
graphy ot the igneous rocks of the area. 
These dykes are of the same type, and probably belong to the same period of intru- 
sion, as the late Carboniferous east-and-west dykes of Central Scotland. 
(b) Teschenite Sills—On the rocky foreshore between Bervie Bay and Gourdon 
there is a considerable development of igneous rocks, including a soft green “ serpentine.” 
The ‘‘ serpentine” was formerly mapped as an intrusive dyke, the other igneous rocks 
are contemporaneous porphyrite lavas. From the field evidence, however, it is apparent 
that all are intrusive, and, indeed, that all belong to the same intrusion—a sill with a 
maximum thickness of about 180 feet—consisting of a soft central portion of highly 
decomposed doleritic rock or “serpentine,” above and below which is a hard, fresh 
olivine analcite dolerite or teschenite. The teschenites are in places rich in acid 
“segregations.” Towards the top and bottom of the intrusion they become strongly 
porphyritic with tabular crystals of plagioclase felspar, and such parts of the rock 
present a deceptive resemblance to the Crawton basalts. Junction specimens show the 
chilling of the upper and lower margins, and clear evidence of the intrusive character 
of the mass is seen from the way in which the igneous rock everywhere interdigitates 
with the overlying and underlying conglomerates and tuffaceous sandstones. Another 
small teschenite intrusion occurs at Bob’s Cove, Kinneff. 
These alkali-rich intrusions have in all probability been derived from the same magma 
as the Carboniferous volcanic rocks of the Midland Valley. Their affinities are certainly 
with an ‘“‘ Atlantic” series rather than with the “ Pacific” or calc-alkali series to which 
the lavas and intrusions of the Lower Old Red Sandstone period so obviously belong. 
XV. Summary oF THE CHIEF STRUCTURAL FEATURES. 
Along the greater part of its course across Kincardineshire the Highland fault forms 
the boundary between the Downtonian-Lower Old Red Sandstone series and the older 
* The New Statistical Account of Scotland, vol. xi., Kincardineshire, p. 72, 1845. 
