CHAP. XXXVIII 
THE PLATEAU OF SMALL ISLES 
227 
material may be noticed among the basalts. Both of these can be well seen 
on Dim Mor, about 100 feet high, which is represented in Fig. 271. The lower 
band, four or live feet thick, is here a rather coarse conglomerate which lies 
upon a sheet of scoriaceous basalt that extends up to the base of the Creag nam 
Faoileann. It is directly overlain by another basalt, about 30 feet thick, 
which dips seawards and forms a broad shelving platform, whereon the tides 
rise and fall. On this stack a second coarse conglomerate, about 10 feet 
thick, forms a conspicuous band about a third of the height from the 
bottom ; it is composed mainly of well-rounded blocks of various lavas up to 
1 8 inches or more in diameter, but it contains also pieces of Torridon Sand- 
stone. It is covered by about 60 feet of basalt, which towards the base is 
somewhat regularly columnar, but passes upward into the wavy, starch-like, 
prismatic structure. 
If now we trace these two intercalated zones of conglomerate along the 
shore, we find them both rapidly to change their characters and to disappear. 
The lower, though formed of coarse detritus under the Dim Mor, passes on 
the opposite cliff in a space of not more than 60 yards, into fine tuff and 
shale, about six feet thick, which become carbonaceous at the top where they 
are overlain by the next basalt. A hundred yards to the east, the band 
likewise consists of tuffs and ashy shales, which underlie the basalts on the 
Dim Beag, and again show the usual coaly layers at the top. On the east 
side of the gully in the coast, about 160 yards to the north-east of Dim Mor, 
the same band is reduced to not more than three feet in thickness, consisting- 
chiefly of fine conglomerate, wherein well water-worn pebbles of Torridon 
Sandstone and epidotic grit appear among the predominant volcanic 
detritus. This conglomerate is surmounted by a few inches of dark carbon- 
aceous mudstone or shale. Rough slaggy basalts lie above and below the 
band. 
The upper conglomerate dies out, both towards the east and the west, in 
the cliff opposite to Dim Mor, dwindling down at last to merely a few 
pebbles between the basalts. It lies in a kind of channel or hollow among 
these lavas. This depression, in an east and west direction, cannot be more 
than about 65 yards broad. 
Probably still higher in the series of basalts is another intercalation of 
sedimentary layers which may be seen in the little bay to the east of 
Tallabric, rather more than a mile to the west of the Creag nam Faoileann. 
It rests upon a coarsely slaggy amygdaloid, and is from six to ten feet in 
thickness. The lower and larger part of the deposit consists of greenish 
pebbly sandstone and fine conglomerate, largely composed of basaltic 
detritus, but including abundant well-smoothed and polished pebbles of 
Torridon Sandstone, green grit, quartzite, etc. The stones vary from mere 
pea-like pebbles up to pieces two or three inches long, the largest being 
generally fragments of slag and amygdaloid which are less water-worn than 
the sandstones and other foreign ingredients. The uppermost two or three 
feet of the intercalation consist of dark carbonaceous mudstone or shale, 
made up in large measure of volcanic detritus, which may have been 
