Messrs Peach <Sc Home on Old Red Sandstone of Shetland. 83 



over a great part of Lerwick, Quarff, Conningsburgh, and 

 Dunrossness, it so happens that different zones in the fore- 

 going vertical section are brought into conjunction with the 

 gneissose rocks. The true base of the series, however, is 

 exposed in the neighbourhood of East Quarff on the north 

 side of the bay, and again on the south side towards Flada- 

 bister, while still another locality in which the basement 

 breccias occur, is to be seen near Loch Spiggie in Dunross- 

 ness. In each of these localities the breccia varies in charac- 

 ter according to the nature of the underlying rock. Perhaps 

 the finest exposures of this breccia are to be seen on the hills 

 to the north of East Quarff, and round the shore towards 

 Brenista ]N"ess. Here it forms well marked cliffs, the beds 

 being inclined to the east at an angle of 25°, and resting on 

 a highly eroded platform of the metamorphic schists. The 

 prominent ingredient in this deposit round the bay of East 

 Quarff is the underlying rock, which consists mainly of grey 

 schists. Blocks of this material sometimes measure three 

 feet across, retaining their angular edges and showing little 

 trace of aqueous action. 



Near Loch Spiggie, in Dunrossness, the fragments mainly 

 consist of pink syenite and serpentine derived from the under- 

 lying rocks which form the floor on which the breccia rests 

 in that neighbourhood. The occurrence of fragments of these 

 rocks in the basement breccia is of great moment, as it helps 

 us to fix the age of the pink syenite and serpentine between 

 Quendale Bay and Loch Spiggie. 



In the bay west of Brenista, the overlying series of the 

 Brenista fiags is thrown against the breccias and underlying 

 schists by a fault which is traceable inland in a IJ^.N.W. 

 direction. Between East Quarff and Eladabister, however, 

 the relation between the two is seen in several fine exposures 

 which show the gTadual passage from the breccia into the over- 

 lying chocolate fiags. But farther, about half-way between 

 these two localities, the basement breccia, which is upwards 

 of 200 feet thick on the shore, thins out inland to a few feet, 

 and in some places disappears altogether, so that the Brenista 

 fiags rest directly on the underlying rocks. This interesting 

 phenomenon evidently points to a gradual sinking of the 



