954 DR ROBERT CAMPBELL ON > 
material. It seems to me that all the conglomerates are old torrential gravels rather 
than beaches, and for two reasons. (1) The composition of the conglomerates is 
suggestive. In the magnificent section at Crawton, for example, the rocky foreshore 
coincides in position with the eroded surface of the Crawton basalt, with many of the 
hollows still filled with conglomerate. This uneven junction may be traced round an 
isolated stack which extends seawards for about twenty yards, and may be followed 
again in the cliff section to the north. If the overlying conglomerate were an old 
beach, one would expect it to contain a big proportion of boulders of the lava, whereas 
only a very few can be seen, and that in an exposure, which, as indicated above, extends 
over a considerable area. Indeed, in all the conglomerates the admixture of rock 
types brought together from widely separated areas suggests powerful torrents as the 
chief eroding and transporting agents. (2) The numerous storm beaches on the 
Kincardineshire coast have received their constituent boulders in large part “‘ ready 
made” from the disintegration of the local Old Red Sandstone conglomerates, and may, 
therefore, well be compared with the latter. Both show a characteristic imbricated 
arrangement of their boulders, and, since the general trend of the coast is parallel to 
the Highland Border, and therefore probably to the successive shore lines of the Old 
Red lake, we should expect the boulders of the conglomerates—if those represent 
beaches—to overlap in the same manner as the stones of the modern beach. Wherever 
the imbricated arrangement has been observed, however, in the conglomerates, it 
indicates that the boulders were placed in their present position relative to one another 
by currents coming from the north or north-west. 
There can be no doubt, I think, that the accumulation of the boulders and their 
exquisite rounding must be ascribed mainly to the action of torrential rivers rather 
than to wave action along the shores of a lake. None of the beaches of the great fresh- 
water lakes of the present day are at all comparable with the coarse conglomerates ; 
but the latter recall at once modern torrential flood gravels and the fluvio-glacial gravels 
of late Glacial times. | 
In short, the coarse conglomerates of our area represent the coarse torrential gravels 
swept outwards from a lofty ‘‘ Highland” mountain range on to the margin of a wide 
frontal plane, across which extended a great shallow fresh-water lake or chain of lakes 
where were accumulated the finer gravels, sand, and silt now consolidated to form the 
finer conglomerates, sandstones, and shales. To the north and west along the flanks 
of the mountains, and to the east beyond the limit of the present land, stretched two 
lines of active voleanoes. The former supplied the acid lavas and tufts, and, indirectly, 
the volcanic conglomerates; from the latter were extruded the basalts and basic. 
andesites. The eastern voleanoes may have formed a chain of volcanic islands, but no 
evidence of that has been detected within the area with which we are concerned. 
