388 Proceedings of the Boy at Physical Society. 
of the Eoyal Society of Edinburgh," vol. iv. p. 200. This 
digression from my glacial story, I trust, is of suflScient 
interest to be pardoned. 
In addition to the glacial markings on the rocks, I met 
with several deposits of drift, in which rounded, striated, 
and smoothed stones were not uncommon, some of the 
deposits being from 12 to 14 feet in depth. Perched blocks, 
but not in abundance — some of large size — are scattered 
about, and, with the rounding and smoothing of the face of 
the rocks, are to be found over all this group of islands. 
Unst. — Our next move was to Unst, the harbour of Balta 
Sound being our head-quarters. Here, too, the effects of 
glacial action were plainly to be seen. The serpentine rock 
has suffered seriously; and although much acted on by 
rain, frosts, &c., the rounded outline of the hills tells plainly 
of the grinding they have undergone. Euts and striae are 
also rare here. I met with a few on the cliff at Hagdale, 
in Haroldswick Bay, where there is a thick deposit, com- 
posed of clay, in which polished and striated stones, of 
various sizes, are plentiful. Part of this deposit had recently 
slipped off the rock, and here the markings were as 
splendidly shown as if the grating masses had only passed 
over it a few days before. The direction of the striae, &c., 
are nearly W.N.W. and E.S.E. The hills of the Muckle and 
Little Heogs lie to the north of this spot (Hagdale), and a 
slope from about 20 feet above the level of the sea hence 
to the top of the Muckle Heog, rises gradually to the height 
of at least 500 feet. In this slope lies the famed mine for 
chromate of iron. On reaching the top of this hill I found 
the W.N.W. end vertical and polished, to the depth of at 
least 150 feet, and before it a depression is formed, remind- 
ing me much of that in front of Arthur's Seat and Salisbury 
Crags, The hills to the north of the Heogs slope towards 
it, and down these, no doubt, the crushing agents came. The 
vertical or storm side of the Heog had evidently resisted a 
portion of the destroyer, and turned the greater part on its 
western flank, and thus the main body passed down the 
valley towards Haroldswick, as evidenced by the greater 
