40_ > MR JOHN S. FLETT ON 



outcrop we are crossing, and through the promontory between Kirkwall and Inganess 

 Bay the general dip is to the north-east. At the south-west corner of the latter bay 

 the fault already described by Peach and Horne, forming the western boundary of this 

 area of John o' Groats beds, is well seen in the shore, letting down the red sandstones 

 sharply against the blue grey flags. These are the flags which in the old quarries at 

 the East Hill, Kirkwall, rather over a mile away, contain the Thurso fossils, according 

 to the observations of Hugh Miller.* They form a triangular area between two consider- 

 able faults ; and though in the land north-east dips prevail, as also along the east shore 

 of Kirkwall Bay, along the northern coast from Carness to Meil Bay, a succession of folds 

 repeats them. 



Continuing our section eastwards, we find that the sandstones of Inganess dip 

 north-west to the fault, and at their eastern edges are bounded by grey flags with a 

 similar dip. About five miles from Kirkwall, at Quoyburray, in a quarry near the road, 

 the beds lie nearly quite horizontal, and from that point onwards the dips are south- 

 east and generally steep. The axis of the anticline runs approximately from Sebay 

 Mill to the Ness of Tankerness in an E.N.E. direction, as along this north-west shore of 

 Deersound the dips are slight and rolling ; and while, to the east of this, at Yinistay 

 Head and through Tankerness we have the north-west dips, in Deerness these have 

 rolled over to the south-east. At Dingieshowie the yellow sandstones are let down by a 

 fault, but maintain the general south-east dip ; and from here, along the shore to the 

 Castle, they lie in a little trough, the dips swinging first to east, then to north-east, 

 when they are succeeded by grey flags, which up to Roseness Point have a north dip. 

 Along the shore of Holm Sound the north and north-east dips show that here, too, we 

 are on the south side of a syncline which runs approximately north-east and south-west, 

 but as we pass westwards beyond Graemshall the rocks are much disturbed, and the 

 dips are inconstant and frequently changing. 



In spite, then, of their generally steep dips, the flagstones of the East Mainland are 

 so repeated by these folds that they cannot be regarded as of very considerable thickness, 

 and the disturbance to which they have been subjected renders any estimate exceedingly 

 conjectural. Their fossils are few, yet I found in different places Glyptolepis paucidens 

 (Ag.), Dipterus valencienesii (Sedgw. and Murch.), Osteolepis macrolepidotus (Ag.), 

 Coccosteus decipiens (Ag.), and Diplopterus Agassizi (Traill). 



It is interesting to observe how the section drawn east and west from the Bridge of 

 Waithe to Roseness, through Kirkwall, repeats the main features of that drawn from 

 Skaill Bay to the Start Point of Sanday (sects. 1 and 3). The Tenston fault passes south 

 through Waithe, and the West Mainland anticline is distinctly to be traced in Summers- 

 dale, the rolling beds between Finstown and Kirkwall are those of Rendall and Firth, 

 the Rousay beds recur at Kirkwall, and the broken dislocated flagstones to the east of 

 Kirkwall repeat the structure of the west of Shapinshay and Egilshay. The Eday 

 syncline passes south through Shapinshay to Inganess Bay. The anticline of Tanker- 



* Cruise of the Betsy, p. 394. 



