David Milne, Esq., on Polished aud Striated Bocks. 161 



The following is a list of the different kinds of rock composing the 

 boulders.* 



(1.) Compact felspar, and felspar porphyry, of red, yellow, and 

 fawn colours. These are pretty numerous, and some are about the 

 size of a boy's head. They are not much rounded, and generally of 

 an angular shape. They are exceedingly hard. 



(2.) Coarse greenstone porphyry, almost a sienitic porphyry, in 

 blocks about the same size as the former ; they also are angular in 

 shape. 



(3.) Blocks of claystone tufa, containing zeolite and other kindred 

 crystals. 



(4.) Blocks of greenstone and basalt. 



(5.) Limestone, very compact, containing two species of JEntomos- 

 traca, and some bituminous casts of Ferns and Equiseta. The spe- 

 cimen which I found is of a dark grey colour, with a tinge of lilac. A 

 workman, to whom I shewed it, declared it to be identical with the 

 upper bed of the Burdiehouse limestone, which he had often worked. 



(6.) Limestone of a more lilac colour and coarser in the grain, in 

 which no fossils are distinguishable. 



(7.) Marino limestone. I found two kinds, — one of a yellow co- 

 lour, and coarse in the texture, containing a large Productus, fully 

 3 inches in diameter-; the other of a dark colour, and very minute 

 texture, full of marine shells. Of this last kind, some of the speci- 

 mens were slaty, almost approaching to shale; others were compact, 

 resembling the ordinary limestone which is quarried for use.f 



(8.) A few masses of coarse red sandstone, containing quartz peb- 

 bles, apparently of the old red sandstone formation. 



(9.) Rounded pebbles of pure quartz, similar to what occur in the 

 old red sandstone conglomerate. 



(10.) Soft yellow sandstone (of the coal-formation), containing cast 

 of a Lepidodendron. 



(11.) Soft brown marly sandstone (of the coal-formation), contain* 

 ing portions of Stigmaria. 



(12.) Numerous pieces of soft white coal sandstone. 



(13.) Fragments of shale and coal. 



(14.) Blocks of greywacke. 



The boulders now described were imbedded in the clay which 

 formed the first deposit immediately above and in actual contact 

 with the smoothed rocks in the gorge. 



Mr Maclaren, in- his Sketch of the Geology of Fife and the Lo- 

 thians, states that at the bottom of Sampson*s Ribs, where the rail- 

 way tunnel now is, a clay deposit was discovered when the tunnel 



* Specimens have been deposited in the Museum of the Koyal Society, where 

 also will be found portions of the smoothed and sti'iated surfaces of the rocks. 



t I found among the clay several septa of the Encrinite, derived probably 

 from the marine limestone blocks. 



VOL. XLII. NO. LXXXIII.— JANUARY 1847. L 



