800 B. N. PEACH AND J. HORNE ON THE 
Old-Red-Sandstone occupy the strip of low ground from Levenwick 
southwards by Loch Spiggie to Quendale bay. Now from Channer- 
wick southwards along the hill-tops to the Wart of Skewsburgh 
(854 feet), smoothed blocks of the red flags, varying from 2 inches to 
a foot across, are to be found in those places where the peat has 
been worn away. ‘These blocks are readily detected on the top of 
Skewsburgh hill, in spite of their being bleached by the peat. 
Further, if we cross from Channerwick to the west coast, and 
traverse the coast-line from Maywick to Loch Spiggie, numerous 
blocks derived from these areas are likewise met with. In the 
hollow which runs south from Maywick to Bigton, striated blocks 
from the red flags are strewn on the eastern slope overlooking the 
valley, the largest of which have been used as building-material by 
the villagers of Maywick. Again, on the hill-slope about a mile 
east from Bigton, blocks of flaggy sandstone are very numerous ; and 
they likewise occur very abundantly in the Boulder-clay on the top 
of this hill. On both sides of Bigton Bay, the sections of Boulder- 
clay contain numerous fragments of red flags, though the majority 
of the stones are made up of the underlying schists. Close to the 
point where the sand-bar joins the island of St. Ninians to the 
Mainland, a similar admixture of stones, derived from the red flags 
on the east side of the island, is to be seen in the Boulder-clay 
underneath the blown sand. And so, too, southwards towards Loch 
Spiggie, wherever patches of Boulder-clay have escaped denudation, 
the same phenomena are observable. 
Again, on the slope of Fitful Head, at a height of 800 feet 
by aneroid measurement, there are small patches of this deposit, in 
which we observed smoothed stones of syenite and coarse grits im 
situ to the east; while on the hill-top (929 feet) blocks of syenite 
were noted, which must have been carried up the slope. These facts 
unquestionably point to the same westerly flow of the ice; but at 
the base of the slope, along the margin of the syenite area, there is 
an excellent section of morainic stony clay, in which blocks of 
schist, syenite, and Old-Red grits are commingled. This deposit is 
evidently the product of a later glaciation, when the Fitful Head 
shed its own glacier, and when the detritus which had accumulated 
on the slope during the primary glaciation was rolled downwards to 
the low ground at the foot of the hill.” 
From the evidence now adduced it cannot be doubted that, during 
the primary glaciation, the great mer de-glace crossed the Mainland 
from the North Sea to the Atlantic. We might have multiplied the 
evidence considerably by referring to the Boulder-clay distributed 
over the other islands; but we haye confined our observations 
to those lines of section where there is the greatest variety of rock- 
formations, in order to show both the strength and harmony of the 
evidence. re leaving this division of the subject, we ought to 
state that, though we carefully searched the numerous sections of 
Boulder-clay in the different islands, we found no traces of shells in 
the deposit. 
There are certain phenomena still to be disoussed, which indicate 
