424 PROFESSOR GEIKIE ON THE 
3. Very soft crumbling grey and red pebbly sandstones, and conglomerates of well- 
rounded pebbles, with bands of red shale, 300 or 400 feet, seen below Glenbogie, where 
the valley is cut out of this soft series. 
2. Red shales, with calcareous red nodules, 40 or 50 feet ; seen in small ravine to east of 
Glenbogie. 
1. Band of red and yellow conglomerate and breccia, sometimes with calcareous cement, 
This lowest deposit immediately underlies the shales at the last-named locality, and 
rests on the crystalline rocks. 
It will be afterwards seen that in several respects the Rhynie section affords 
points of comparison with those along the borders of the Moray Firth. The 
basement conglomerate (1) is a counterpart of that which occurs on the shore at 
Buckie, in the markedly calcareous character of parts of its matrix, and in the 
occurrence in it of cornstone. It is probably only a few feet thick to the east 
of Glenbogie, though it may swell out southward. The shale zone (2) closely 
resembles the shales of Fochabers, Tynet, and Gamrie, but is redder in 
colour. The calcareous nodules are flattened oval or circular concretions of 
hard, finely crystalline, grey limestone. So exactly do these present the char- 
acters of those so long known from the localities just mentioned, that they may 
be expected to yield an adequate number of the typical fossils.* 
Immediately above the shales comes the series marked No. 3, which con- 
sists mainly of soft sandstones, with many well-rounded pebbles partly 
scattered irregularly through the strata, but more usually grouped in lenticular 
patches, layers, and nests. The curious interrupted arrangement of these layers, 
and of the sandy strata, with a dominant inclination in one direction, seems to 
point to deposit against a steep bank or shore. Bands of conglomerate, formed 
by the aggregation of similar well-rounded pebbles, occur in the group, one 
particularly striking bed lying nearly at the base, and close to the top of the 
shales. While the prevailing colour of the group is pale reddish-grey, every 
gradation of tint may be traced to deep blood-red. A considerable interval of 
obscured ground separates the highest strata of the third group, near Glenbogie, | 
from the sandstones of Rhynie (5). But a little to the south-west, beyond the 
Burn of Craig, there occurs in that part of the series a remarkable bed of black, 
compact, finely-vesicular diabase, or diabase-porphyrite. It has been partially 
quarried for road material in a knoll which rises out of the surrounding drift. 
It very closely agrees in petrographical characters with many of the dark basic 
volcanic rocks associated with the Old Red Sandstone in the central valley of . 
Scotland. Though I did not observe its immediate relations to its neighbouring | 
strata, I had little doubt that it is a truly contemporaneous volcanic product, 
* It was from these nodules that Dr Gorpon obtained the fossils already referred to. He informs 
me, however, that no record seems to have been kept of them, and that he cannot say what were the 
species. a 

