794. B. N. PEACH AND J. HORNE ON THE 
examples of cross-hatches were observed near the fort at Lerwick, also 
north of the docks, and again near the village of Sound, the older 
markings running §.W. and the newer ones 8. 40° E. to E. 40°S. 
In the long tongue of land stretching southwards from Quarff to 
Sumburgh Head, the striew belong mainly to the later glaciation, the 
direction varying from E. 29°S8. to 8. 34° E.; about half a mile from 
Boddom, however, by the roadside, some examples occur in which 
the trend is W.3°-9°N., produced by ice moving in a westerly 
direction. 
From the evidence we obtained in Bressay, it is clear that the 
south-westerly system is the one which is most prominently marked 
in that island; indeed, so abundant are the ice-markings belonging 
to the early glaciation, that some parts probably escaped the move- 
ments of the later glaciers altogether. This much is certain, that 
the local glaciers of the Mainland were only able to override the 
north-western portions of Bressay. Along the eastern coast, from 
Heogan to the lighthouse, as well as by the roadside from Cullensbro 
to Gardie, the trend varies from W.20°S8. to 8. 30° W. But on the 
slopes east of the Wart the later system points 8. 20° E. to HE. 16°S8. 
In the island of Meikle Rooe, which lies to the west of the 
Mainland, the average trend is N. 30° W.; in Papa Stour it varies 
from N. to N. 28° W.; while in Foula, the most isolated of the 
Shetland group, situated about 18 miles to the 8.8.W. of the village 
of Walls, well-marked striations were observed, running N.W. and 
W. 30°N. 
Altogether we recorded upwards of three hundred and twenty 
instances of striations in the Shetland Isles, the great majority of 
which belong to the primary glaciation. 
IV. Bourper-Cray. 
The Boulder-clay and morainic deposits confirm in a remarkable 
manner the conclusions already established regarding the double 
system of glaciation in Shetland. The rich variety of rocks, not 
only in the Mainland, but also in Unst and Fetlar, enables us to 
test the truth of these conclusions by noting carefully the distri- 
bution of the included stones and the sources whence they were 
derived. Ifit be true, as has just been stated, that the ice moved 
from the North Sea to the Atlantic during the primary glaciation, it 
naturally follows that the Boulder-clay or moraine profonde occurring 
to the west of the serpentine areas in Unst and Fetlar should con- 
tain a certain percentage of stones derived from those areas. ‘The 
very same reasoning is also applicable to the Mainland; and in order 
to show how completely the dispersal of the stones in the Boulder- 
clay substantiates this conclusion, we shall briefly describe a series 
of traverses we made in Unst, Fetlar, and the Mainland, where the 
rocks vary in lithological character, indicating the variations in the 
Boulder-clay and the distribution of the included stones. 
found Balta Sound, in Unst, this deposit is sparingly distributed, 
only occasional sections being visible on the north and south sides 
of the bay, the included blocks being almost wholly derived from the 
