938 DR ROBERT CAMPBELL ON 
in great abundance, but in the conglomerates underlying the Tremuda Bay lavas they 
are almost entirely wanting, their place being taken by an abnormally large number 
of rhyolites and acid andesites. Locally, too, and particularly in the conglomerate 
just south of Strathlethan Bay, boulders of a coarse grit resembling the ‘‘ Haggis rock” 
of Caradoc age of the Southern Uplands are fairly numerous. 
At four horizons the conglomerates are interbedded with contemporaneous volcanic 
rocks, 
(a) At Stonehaven harbour the basement members of the group, brown micaceous 
pebbly sandstones, are separated from the coarse quartzite conglomerate of Downie 
Point by a considerable thickness of acid tuffs, with a few bands of coarse volcanic 
conglomerate. 
Three lavas are indicated in the Geological Survey map as occurring in the vicinity 
of Stonehaven harbour, but I have been able to find only one crystalline igneous rock, 
and that an intrusive quartz dolerite. . 
(b) In Strathlethan Bay the Downie Point conglomerate underlies a series of soft 
tuffs and tuffaceous sandstone, with which again are associated volcanic conglomerates. 
Here, too, we find the lowest lava flow of Old Red Sandstone age in Kincardineshire—- 
an augite andesite. It forms the small island of Carlin Crag, but is truncated by a 
fault and does not appear in the cliff section. 
(c) After a long interval, represented by a great thickness of conglomerates, another 
zone of acid tuffs is found in Old Hall Bay, just south of Dunnottar Castle. 
(ad) At Tremuda Bay the highest members of the Dunnottar group include a series 
of at least six flows of olivine basalt of a coarsely crystalline, doleritic type, each of 
which consists of a massive central portion with well-marked scoriaceous upper and 
under surfaces. ‘The second shows good columnar structure. The slaggy upper surfaces 
occasionally enclose “veins” of sandstone. The bottom lava has flowed over a bed of 
soft mud, portions of which have been caught up in the lower scoriaceous surface. At 
the north side of Thornyhive Bay the lavas are truncated by the important fault already 
alluded to, and the top of the series is not seen. 
The lava near the lighthouse at Todhead Point is a doleritic basalt of the same 
type as the above, and, along with the underlying conglomerates, may perhaps be 
considered as belonging to the Dunnottar group. It shows a very slagey upper surface 
with the characteristic sandstone veinings, and has been described and figured by Sir 
ARCHIBALD GEIKIE.” 
Inland sections are sufficiently numerous to show that, along the steeply inclined 
northern limb of the Strathmore syncline, the Dunnottar group maintains the same 
general characters which it exhibits in the coast section. Quartzite conglomerates 
predominate, but at intervals there occur acid tuffs and volcanic conglomerates. On 
the south-eastern slope of Carmont Hill, near Square’s Knap, a vesicular augite andesite 
is associated with a coarse voleanic conglomerate, and, although the lava is not quite of 
* Ancient Volcanoes of Great Britain, vol. i. p. 308. 
