1858.] MUECHISON NOETHERN HIGHLANDS, ETC. 413 



lighthouse stands. The chief mass of the roek is a finely micaceous 

 light-grey sandstone, in parts reddish, and weathering brownish-red 

 with a slight dip to the E.S.E., or away from the older rocks, which 

 range from the Fitful Head to the N.N.E. 



In the more flag-like and thinner beds of this sandstone, and at 

 the very summit of the rock on which the lighthouse stands, Mr. 

 Peach and myself found numerous fragments of plants. Hence we 

 had no hesitation in considering this sandstone, and a fine con- 

 glomerate which it contains, to be of the same age as the rock which 

 we had left at North E-onaldsha in the Orkneys, and to be really a 

 part of the Old Eed series. 



As we steamed forwards to Lerwick, the cliffs of Lumboga Head, 

 Troswick Ness, No Ness, and the Isle of Mousa seemed to consist of 

 thin-bedded rocks pertaining to the same series; and in passing 

 close along the western shore of the Isle of Bressay, we saw that 

 the strata were thrown over on a dome-shaped rock of red colour. 

 This mass and the overlying grey beds near the centre of the island 

 are evidently carried under the beds of sandstone constituting the 

 promontory on which the Lighthouse is placed. These beds, of light- 

 grey colour and much charged mth mica, dip to the E.N.E. at about 

 30°, and in lithological character are not unlike some of those of 

 Somburgh Head. They contain casts of the trunks and branches of 

 trees, the stems of which are fluted and void of joints. 



At Lerwick, which is just opposite Bressay, we visited the quarries 

 on the shore to the south of the town, which have afforded a consi- 

 derable number of those plants, including those brought to me some 

 years ago by my friend the late RightHon. H. Tufnell*. The sandstone 

 in which these plants are imbedded is of a brownish-red colour, whilst 

 under Queen Charlotte's Fort, at the north end of Lerwick, the rock 

 passes down into a thick-bedded mass with a few rounded pebbles, 

 almost a conglomerate. 



Although the ichthyoHtes of the Caithness flags have not yet been 

 discovered in the Shetland Isles, the existence of strata of this age 

 in the environs of Lerwick is placed beyond a doubt, by the discovery, 

 in flaggy beds, of the same little Crustacean (the Estherid) which 

 occurs at Thurso and EjrkwaU. 



Again, judging from the superposition of the sandstones of the 

 Bressay lighthouse to a great inferior mass of rocks, there can be 

 little doubt that these, as well as the plant-beds of Lerwick, pertain 

 to the younger portion of the Old Red Sandstone f. 



On inspecting several specimens which a quarryman had collected, 

 one of which was nearly 5 feet long and 6 inches broad, it was clear 

 that none of these plants possessed joints, as already noticed by 

 Dr. Hooker J. They were simply long fluted stems without any 



* Quart. Journ. Greol. Soc. vol. ix. p. 49. 



t In his new map, Professor Nicol has acciirately distinguished the Old Red 

 of the east coast of Scotland from the much older Cambrian rocks of the west 

 coast ; and in his Greological Map of the British Isles, Mr. Knipe had also pro- 

 perly extended the Old Red along this portion of the Shetland Isles. 



X Quart. Journ. Geol. Soc. vol. ix. p. 49. 



